When first got mine a 1995 the temp got to 236 in traffic I freaked out and got on the interstate and it cooled,done done some research and discovered they are designed to run like that now I’m at ease with it.
Exactly, it's the time sitting in traffic that can cause that stress and anxiety. That was what I was going for with this demonstration. Even with the cars sitting in the mid afternoon heat, they will perform as designed and keep from overheating as long as the cooling system is functioning as designed. Thanks for the comments👍
I have a 1988 L98 car, and I've researched this issue thoroughly. The 1992-96 LT engines are fundamentally the same. Notably, the LT engines have a 'reverse flow' cooling system but, as you showed, the factory temp specs are the same. Traditionally, small-block Chevy engines were set to run at roughly 180F. As you said, additional heat reduces hydrocarbons before the exhaust gasses reach the catalytic converters. So the extreme temperatures in the engines of this particular era were a factory 'trick' to pass emissions. The coolant passing through the throttle body is only intended to prevent icing in extremely cold environments. The factory 15psi radiator pressure cap raises the coolant's boiling point to 262F, which is why temps of 217-230F are sustainable. The factory thermostat opens at 195F, so it stays open all the time once the engine is at operating temp. That's why installing a cooler thermostat never makes any difference. Clearly, the engines can survive long-term at the higher temps. With proper maintenance, they are good for around 200k miles. However, you can extract a little more power (maybe 5-7 HP) from bypassing the throttle body (an easy mod), thereby reducing intake air temperature. To significantly reduce real-world coolant temperature, you'll need a higher capacity radiator, a cooler thermostat, and modified cooling fan on/off settings, but there are related issues. The engine management ECUs of this era had fixed maps for fuel mixture and ignition timing, with little or no ability to 'learn and adapt'. So lower baseline coolant temperature may actually decrease power output by causing the ECU to use an extra-rich, 'cold engine' fuel mixture and timing map. The extra-rich mixture may, in turn, 'wash' oil from the cylinder walls, accelerating wear. Finally, all the factory-set internal engine tolerances, such as ring gaps and bearing clearances, are affected by temperature. That being said, you can get aftermarket ECU chips specifically tuned for lower coolant temperature. One thing most people overlook is that the center section of the front air dam loses its proper shape over time, reducing the airflow through the radiator while the car is moving. It folds down and back. Also, that cooling intake sucks in a lot of debris like leaves and plastic bags, which block airflow through the radiator and AC condenser.
Michael, excellent writeup and information regarding the cooling systems for the C4's. Like you stated, bypassing is an option if an owner is uncomfortable with how hot their C4 is running, but beware of the unintended consequences of deviating from the factory settings. Thanks for taking the time to share your knowledge with everyone
@@VetteSource Thanks VS. The throttle body coolant passage is only there to prevent icing of the throttle body; it has no engine cooling effect. But I do take your general point, and I've previously given that a lot of thought. There is an air temperature sensor in the intake plenum, which helps the ECU choose the appropriate fuel/timing map. A cooler reading from that sensor equates to cooler ambient air. Since intake air temp is a fundamental and immutable factor in combustion characteristics, it's a prime determinant for the ECU, not to be ignored under any circumstances. The throttle body coolant passage does have significant control over TB temperature, but does NOT have absolute control over intake air temperature. Ambient air temp, TB temp, and plenum case temp combine to create a net actual air temp inside the plenum. I'll try to illustrate why bypassing the throttle body coolant passage is safe under most conditions, but not all possible ones. At one extreme, perhaps you're in Canada in January and the ambient temp is -40F. Combined with the warming effect of the TB coolant passage and plenum case temp, let's say net plenum air temp is +80F. The ECU has a map for that. At the other extreme, perhaps you're in Death Valley, the ambient temp is +120F, and the net intake air temp is +210F. The ECU has a map for that as well. Bypassing the TB coolant passage and reducing net plenum air temperature simply causes the ECU to select a different air temp factor for its calculations, which it is perfectly capable of doing over the widest expected range of net intake air temps. If TB temp dips below +32F, there is a very real risk of ice forming inside it, the severity of which is determined by incoming air temp, duration of exposure, airflow volume per unit of time, and the humidity level of the incoming air. This is why the factory incorporates the TB coolant passage. But, given that the TB is attached to a hot engine via the intake plenum, icing is unlikely under all but the most extreme conditions. While there is obviously a coolant temp sensor connected to the ECU as well, the expected range of normal operating temperature for mapping purposes is predicted to be between +195F, at which the thermostat opens or closes, and the fan-controlled max of +230F. Coolant temp is mostly a pass-fail factor based on whether the coolant and oil are above or below +195F. Below +195F, the engine is considered to be 'cold'. There are, of course, some 'gray areas' involved in all of this. Welcome to the realities of managing internal combustion engines over an extremely wide range of operating conditions. Contrary to popular belief, the factory really does have a clue about what that requires. Whew! OK, if all that doesn't cover it for someone, I guess they'll just have to attend automotive engineering school.
@@VetteSource Thanks again. I have thought about starting a channel, but I'm aware of how much time and effort that can require, and I already have a lot on my plate.
Really good demonstration. Just to add a little to the already great comments on this. The very early C4s ran even hotter. I have a 1984. When you look up the service information in the manual the temperatures that it gives for the fan cycle are not correct. If you look into the electrical manual for that year it gives the correct closing temperature for the cooling fan switch. Are you ready. The correct cooling fan switch closing temperature is above 238 F. If the vehicle is sitting still that is when the cooling fan will turn on. It will turn off at about 221 F. This was true of the early model C4s. Starting in 1985 there was the standard cooling system and the heavy duty. The heavy duty had an auxiliary cooling fan but again the fan did not turn on until, you guessed it 238 F or above. By 1987 the control of the cooling fan switch closing temperature was changed to above 228 F. This change allowed the system to operate more in line with what was demonstrated in this video. I worked on these cars under warranty and it was very difficult to explain to customers there vehicle was working as designed. Those of you have commented on this are exactly right. The running temperatures on these engines was necessary to accomplish more complete combustion during idle and to optimize the catalytic converter efficiency. Yes, I saw a lot of stupid stuff done to make the cooling fan run all the time, and yes I saw some fires as a result of it. You folks all have done your research. Good comments
Randall, thanks for sharing your personal insight from the field. That's the kind of valuable real world information that's gold for a new generation of Corvette owners working to keep these now classic Corvettes on the road. Considering how thorough GM likes to be in regards to the mechanical side of the cars, you would think they'd have done a better job communicating the normalcy of high engine temperatures to the new owners. However, I think the aftermarket Corvette suppliers are partially to blame with all the cooling fan bypass kits they were hawking during the 80's and 90's to make your car run cooler and more "efficient". Once they started advertising those, the urban legend of "your Corvette runs too hot" spread like wildfire. They should see how hot early 427 big block Corvettes like to run😁.
Excellent information the both of you. Understanding all of this, are there any advantages to "try" and run the system cooler if emissions are not a concern, say with no cats? Horsepower wise?
I found when I bought my 95 LT1 6-speed that she was heating up faster and too slow to cool. I went under the hood with a flashlight and saw the front of the radiator was packed with leaves, as these cars are road vacuums. Cleaned them out and she ran much cooler. Just a word of advice, check the front of your radiator.
Enjoyed the video, very informative. I can now drive around on a hot day and leave my Valium at home. I could not get used to seeing that temperature up that high BUT it's true no lights came on and it never overheated. Getting used to it now. Love my C4 !
@@VetteSource Having such a narrow normal range on the needle is strange for how hot these run. I watch my temp on the digital now knowing where it should be.
Thanks so much for video. The analog gauge was definitely concerning to me the first time I saw it get so close. 2 years with the car and I’m a lot more used to how it runs.
No problem, glad to do it👍. I found myself having to revisit the service manual to make sure I wasn't losing my mind when I noticed the gauges juat about being pegged out.
General motors needed a way to get the EPA off their back so they can sell some cars and getting these cars to run hot was the answer to passing the smog test. If I'm not mistaken my car comes with a 185 thermostat, that's the temperature the LT1 is designed to run 80% of the time. setting in a traffic jam at letting your car bake at 220 to 230 until you get moving has absolutely no advantage but a disadvantage regarding long-term unnecessary wear to your engine and all components connected to . I suspect that's why these cars love alternators/batteries. Its not good on not just the engine but the components bolted to it including the transmission. heat is the enemy to any engine. It also puts unnecessary coolant pressure on your coolant system causing components to fail in which otherwise never would have if it was running at a lower temperature/pressure, That's why most of the time your plastic sides of the radiator will blow out when you're running hot. it also puts on necessary strain on your heater core. The piston rings in the small block Chevys are just like any other internally that's why a lot of these Corvettes have that poof of smoke on startup caused by excessive heat on the valve seals. Call summit racing equipment tech department or jags high performance and they will refer you to a kit that's designed to convert your existing system to run cooler. Don't run these fans on a manual toggle switch or wire them straight to the battery you're just asking for trouble. do it the right way and you will have a car that runs 185 and will never run past 210 no matter how long you set. Well that's my two cents everyone can do what but my car isn't running at no 230° in a traffic jam for absolutely no reason other than burning off a little extra carbon. Well my baby isn't taking one for the team.
Thanks for a good video reassuring owners about high coolant temps on C4 Corvettes. One thing I haven't seen addressed is to check the accumulated debris on the radiator itself. I bought a '94 Vette that consistently ran hotter than normal. After much investigation, I discovered that there was significant buildup of leaves/debris on the radiator core -- in the tiny space between the AC condenser and the radiator (about an inch in between). As you know, the C4 sucks up leaves and road debris like a great Hoover vacuum -- which is sometimes deposited on the radiator itself. It's difficult to see, but with a good light at the right angle, you'll see it. The best solution would be to unbolt everything and clean it all out. I was able to attach a toothbrush to a thin stick, which I could use to gently scrape the leaves off fins of the radiator, and clean other areas as well. My cooling issues were solved immediately.
Yep, good point. Thanks for sharing the information. The cooling systems do a great job at drawing in all that road debris and trash until it affects the operating temperature like you mentioned.
Yep, it is HOT in Houston....braver than I am on letting my '96 get hot....just changed the coolant and what a fun adventure on a warm Thursday in Sharpstown! Previous owner just had straight water in the radiator, so wanted to get the right stuff in the system. Amazing how those cooling fan work just as designed. Great video, your having the same ish that I'm having on the HVAC controller...enjoy!
Oh yea, summertime in Houston. Good idea to get that straight water out of the system, that makes a mess with cars that were originally equipped with Dexcool. Thanks for the comments👍
Yea, that bleeder valve sure is an interesting engineering solution to removing air from the system. If it wasn't spelled out whilst their purpose was, most people would miss them.
228 is the set point for full high speed fans per the factory service manual. My car hits 228 exactly when high speed fans come on. Mines a 94 loaded admiral blue 64k miles and mint...I'm also the original owner.
Late to the video, having a 90 with the L98. I had to do a lot of service due to age not mileage. I didn't notice any high temps with the old stuff, when I bought it. It had an oil leak at the rear of the manifold so while fixing that I pull the thermostat. It was a 160. The new was a 195 as per Chevy. So, I expected a higher temp. before the fans kicked on. I replaced the old hoses and cleaned out the overflow tank. Checked all other lines due to the old funk in the anti-freeze. I gave it a good flush before adding the mix of new fluid. The thing I missed was looking at the air intake area before driving, it had fur from someone's pet all up in the driver's side. Vacuumed it out, there was no damage to the fins so on my next test ride things were all good. Still a 205-219 in heavy traffic. But the fans kick on and it drops. Same if just at idle in the driveway for a long period of time. THANKS for showing your temps. Different engine but temps are temps.
i got a 97 TA with the lt1 .. when i got the car it ran 220+, i installed a 160 thermostat and wired both fans with relays and fuses so the left fan comes on with the key and the right fan is on a toggle ... the car runs 180 in stop and go traffic and then drops to 160 on the highway ... these motors make better power at a cooler temp than the factory set them up to run
that's a popular modification, but be sure to watch your wiring modification. I've dismantled several cars that burned to the ground from the relays overheating after that mod...
Ok, mine unmodified LT4 runs around 210 while driving but get up to 230 in idle or at a stoplight. Clearly that’s set from the factory. The issue is that temperature at a stoplight has nowhere to escape under the hood and it puts a ton of unnecessary strain/melting heat on those 27+ year old little plugs, wire connectors, electronic components, gaskets etc…. That’s the crapper about that high temperature on these. So better keep moving in these folks! Thanks for the video Sir!
No problem, I'm glad you enjoyed it. The deteriorating underhood plastic is a real issue on these cars of the 80's and 90's. It definitely makes it a bit harder to keep them on the road, but it's worth it with as much as they are to drive👍.
Clogged between condenser and radiator with leaves, needles etc will cause high temps. Replace stock radiator with aftermarket with increased cooling. Fans come on at 226, off at 215. Since new radiator our 89 hasn’t kicked the fans on since.
It's insane how hot GM made these engines!! I put a 160 thermostat with a manual fan switch, cruising with air flow it runs at 165!! A couple years ago I moved to Florida and I couldn't take the heat!!! I was there for about 10 months and hightailed it back to Oregon!!! Lol but I will say Florida has to have the most corvettes than any other state!! Guaranteed fact! Lol
Funny, that is the truth. Everywhere you look in Florida you're likely to spot a Corvette. There are quite a few of them here in Texas as well, but there's so many roads it's easy to miss them cruising around.
Nice research and information. I ended up installing a triple core radiator, adding Greenwich hood vents along with a larger front spoiler, 160 Stat, and setting my cooling fans to kick in at 170 and 180 degrees respectively. I run a 38350 FiTech software system to control the 427 blueprint SB engine. Before I did all of the cooling work, the engine would smash 245 degrees in a few minutes in traffic. Now that it's wintertime, I can't get above 150! Well, I won't drive her until April again anyway! Thanks for the video.
I really appreciate this video, gives me much more confidence that my 95 car can take care of itself. Would love to get your take on the transmission temperature as well. My fans kick on and bring the coolant temp down pretty quickly, much like you showed here in the video. If the car is moving, the coolant will go from 230 to 185 in a matter of minutes. But, my auto transmission temperatures are really slow to come back down by comparison. Is this typical?
Glad to hear you enjoyed it👍. You know, I completely forgot about the auto transmission temp gauge on the later C4's. Normal cruising temperature should be around 180-200, higher in town. The temperature will come down a bit slower simply because the transmission cooler is only receiving indirect cooling from the fans due to its location in the radiator tanks.
Yeah I just bought my 93 and I’ve noticed Going down the highway is about 200(with the AC off) but as soon as I get home and I by time I get into the garage it’s at about 240!! But if you notice the clamshell is a terrible design! They stop making the functional “gills”that were actually here extractors like the C3 models so there’s no way for the hot air to escape!!
Yep, the c4 front end doesn't lend itself much to cooling if anything gets in the way or there's a blockage. The cooling system was tough for Corvette with the introduction of the C3 in 1968 all the way through the C6's. It wasn't until the fish mouth debuted on the C7 that the cooling system received some extra help.
@@VetteSource yeah exactly! GM should of put more of a cold air induction system in it! And heat extraction system in place for at least the C4! But I thought like the C3 generation they had a better system but I don’t much about them…I’m not a fan of the C3 generation!! I have a buddy whose owned several C3’s(heck still has a ‘68 L88 427 4spd sitting in storage!) owns a 94 C4(owned a ‘84) Owned a’00 C5!! He can tell me everything he knows about them…I just keep forgetting to ask him!!🤣
I have 1993 stock 90k miles my temp runs around 140 to 150 while driving freeway in temp about 80 to 90 for approximately 60 to 90 minutes when I get in traffic jams or sit at drive through 180 at tops, but I'm running antifreeze not distilled water which I would only do in emergency situations.
That seems to be a bit on the cool side, unless you're in a cooler part of the world with mild summers. Do you know if any previous owners made some modifications to the cooling system?
@VetteSource I don't know, but like I said I run antifreeze and drive 90 minutes at a time in 80 degrees temperature always temp gage rarely goes past 1st line which I'm calling 140 unless I'm in heavy traffic which is almost never I drive at either 10am or 6pm Midwest state. This car is just for fun and it wouldn't be fun if it was always running hot or if I'm worried about it running hot while I'm driving it.
Ok, 80 degrees ambient is a cooler temperature for sure than what we see down this way. One thing to consider as well, is that the needle garage on the dash is fairly inaccurate, as pointed out by GM when describing it as a non-linear gauge😁. The best read of your actual temperature will be the electronic reading that can be accessed by pressing the "gauges" button on the DIC
@VetteSource I used the numerical temp gage that you mentioned and I didn't know I had lol and my readings are 179 t0 183 while cruising and 194 while sitting in traffic but this is in 80 degree temperature in Midwest while driving about 75 to 90 minutes almost everytime thanks for the info.
Hey Rocky, thanks for the comments👍. I've seen quite a few of those conversions done and dismantled quite a few C4's that burned to the ground because of it. Unless it's absolutely necessary, I always advise people to stay away from grounding the relays. It's an accident waiting to happen.
I have a 95 Corvette and mine was running hot and and I was told to replace the radiator and thermostat.... But first check your radiator in front and all the leafs and debreeze get hung on front of the radiator so that's what I did and mine I climbed under front of car and hosed it with water hose fixed it itself runs normal...Then when I replaced my air filter I seen it would have been easier to hose it off from there ((But DO NOT get water on your engine)) just hose off the Radiator...
The analog gauges are not linear but they are good enough near operating temperature. The position of the sensors is different, in the cylinder head so they want you before. If you needle goes to the hot side it's clear the car is overheating, in the middle you know everything is good.
Yep, I've mentioned that they aren't linear in a few of my videos. With that being said, the analog gauge really isn't your best indicator for actual temps. Using the "gauges" button on the DIC switch to select " Coolant Temp" displayed under the speedometer is the most accurate indicator, as it uses a different temperature sensor than the analog gauge for its reading.
I don't mess with that bad design. I replaced the plastic radiator, water pump, coolant tank and thermostat when I bought the C4. The 200+ thermostat was replaced with a standard 180 degree GM thermostat. Cat runs normal and fans seldom activate anymore. Passes smog check ok. Runs cool.
I'm not so sure I'd call it a bad design, but they definitely left room for owners to upgrade to their personal tastes. Thanks for sharing the info with the group.
Nice video:) recently drove in hot weather and when I parked I lost a lot of coolant, coolant was boiling and overflowing at the little white reservoir at the front right. What could be the reason for this?
Hey Erminio, glad you enjoyed it. The cooling system in your car is a closed pressurized loop and is designed to raise the boiling point. When you have a situation like you're describing where it boils over, that means the system has been compromised in some way, like a leak, hole, or possibly a damaged head gasket. You will definitely need to investigate further, but be mindful of the hot coolant and how quickly you can be scalded.
now shut the air so the aux fans don't stay on.put the car in drive so the idle is lower. take the car out of your driveway and sit yourself in rush hour traffic fifty miles from home. . your temp gage is bordering on 229 and your stuck in the left lane on a three lane highway and nobody is moving. one other thing. your cell phone is dead because the cigarette lighter is burnt out and didn't charge your phone. now you have your test !
I’m confused. You say the left fan is for normal and the right fan is for when the AC is on. I was under the impression that the three relays for the 1996 fans were wired to switch between a series and parallel arrangement to go from low speed to high speed?
You're thinking of the fan operation on the f-bodies. They both run at low speed during normal operation, and high speed with A/C on. The C4 Corvettes run one fan high speed for primary, and the second fan comes on with the A/C
Hey man . Hope all is well . For the zf6 Tranny...i wanna change the fluid on my 96 lt4. Seem to get multiple answers on what type of fluid to use . You know your shit what fluid should i use in your opinion??
Hey Steve believe it or not the ZF was filled with 10W30 engine oil from the factory. Nowadays, there are several vendors making replacement oil for the ZFs including Amsoil and Castrol. These will be in the range of 10W60 and specifically designed for the ZF gearboxes and specify "synchromesh" fluid on the container.
This can also apply to the 3rd gen Firebirds and Camaros. Nothing grinds my gears more than the know alls in fb groups and the 3rd gen forum who say your car is running too hot or overheating if it's getting up to 220°, it is exactly what they're supposed to run at. Glad to see you back working on the formula too 😄👍
Hey Chris, thanks for chiming in. The temperature urban legend is one that definitely will not go away. Glad to be getting some time to wrench on the Formula myself. It's time to put the red down for paint, so I need the yellow one to cruise around in.
@@VetteSource correct, I think as long as these cars are around that argument will be too 😄 Well no matter which one you pick you'll be cruising in style!
how does the fan know when to come on what controls the switch? is it possible to put a switch in the turns it on a little sooner like at 220 or something?
@@VetteSource The needle would go all the way to real hot though there was no boil over. However, I got rid of it because it started to leak oil then finding out Chevy used silicone as a sealant around the water pump, distributor and bottom pan which dried out over time. The car was 3 years and 2 months old. Chevy knowing this was a problem didn't stand behind it. I sold the car and swore I would never buy a GM product again of which I haven't though I do miss the Corvette.
I understand, Corvettes of all generations are somewhat high maintenance. If you're trying to use as a daily, it's hard to ignore all the little annoyance items like leaking targa tops, squeaks and rattles, computer problems, paint issues, and random component failures that sometimes force you to leave it parked in the garage for weeks on end. However, when your behind the wheel and it's running well, you'll easily forget everything that annoyed you about it in the first place😊.
Yep, that analog gauge on the dash is as close to a modern day idiot light that you'll find. When these came off the assembly line, there was a sticker placed on the cluster explaining that the temp gauge was not linear, so in other words don't rely on it for any degree of accuracy. I should have had my MT2500 hooked in as well to show the readings from the ECM, but forgot to bring it out.
Nope, these cars are both completely factory original. I also have a 1993 40th Anniversary with 27K miles on it, and it follows the exact same temperature pattern.
I have a 96 lt1 I just purchased , did not run , I put in a new fuel pump , opti spark , and waterpump , starts right up , my issue is the coolant fans run constant after starting and I have no heat , any thoughts , I also changed the coolant ect switch in the waterpump
Sounds like somebody direct wired your fans so they would run all the time rather than address any problem that may be present with proper fan operation. This is a big no-no. The relays were not designed to be delivering constant current to the fans and can overheat and catch fire. I've dismantled many Corvettes over the years that had burned to the ground from this modification.
Question I own a 1990 c4 with a 6 speed manual transmission I recently replaced the clutch but I was told that the dual mass clutch is no longer produce so it was replaced with a single mass now my car sounds like a Mack truck, it’s there anything I can do regarding this noise. Thanks
Good morning Abel, Unfortunately the lack of the dual mass flywheels has created the problem you're describing with ZF equipped C4's once the original dual mass is replaced with the single mass. From what I understand, there really isn't much to do about the excessive noise, as part of the dual mass flywheels original purpose was to dampen clutch chatter. At the very least, I would double check tolerances between the flyweel and clutch disc to make sure everything was installed to spec. If you also have your original dual mass flywheel and its not damaged,, you could try having it resurfaced by hand. It's a tedious process, but some people have resorted to that so they could keep the dual mass setup.
Well I got stuck in traffic for the first time today in my 96 Collector's Edition my temp got up to 243 and I just about lost it. Just being honest I'm not ok with this.
Yes that's the electronic digital gage in the center of the dash. That analog gage is junk even though it works like it's supposed to. Just like your car's mine is 100% stock. Nothing but the oil and battery has been changed.
I would look underneath the car in front of the radiator to make sure you haven't sucked up a plastic bag or other debris that is blocking the airflow. I would look at the coolant reservoir level also to make sure you're not experiencing a small leak somewhere.
Sounds like somebody hot-wired your fans to run all the time with ignition on. Check the fan relays mounted on the driverside of the radiator/cooling pod, directly above the frame rail. I'll bet you'll find an extra 12V wire jumpered in there to force the relays to run the fans all the time.
Just because GM made them run hot to meet emissions doesn't mean that is optimal. I have a built 85 that runs at 180 on a holley ecu. My son has a stock 89 that runs at 195-200 with a few cooling upgrades, & chip reflash. Letting the cooling system run over 220 is unnecessary.
I would probably disagree. The computer controlled stock fuel injection system from this generation is designed to burn as much fuel as possible during the combustion process, with the excess being recycled back to the tank through the return line. When you lower the operating temperature of the engine, you may feel more "seat of the pants" power, but it's not as clean or efficient of a burn and tends to foul up the associated fuel injection components and sensors which over time just leads to more maintenance and $$$ spent fixing it. Figure that the GM engineers spent literally thousands of man hours getting the system perfectly balanced between power, fuel economy, and emissions output and you can see why they specified the operating temperature that it runs at. Thanks for the comments👍
No problem at all. I'm always appreciative that you guys enjoy the videos and take the time to comment. Just to clarify, I don't think it's always bad to adjust the coolant temperature to what your comfortable with, but I usually aim these type of informational videos to my viewers that may be more driver orientated Corvette owners than gearheads. I know my fellow gearheads will always find a way to make their car faster, it just gives us an excuse to wrench on them more😁 Have a great week👍.
I'm a first time C4 owner. It's a '96 with the LT4 in yellow. I was questioning the same thing about temperature. I was worried but now I'm not. Any more tips for me is immensely appreciated. Thank you.
Hey James, that's great! Glad to hear the video was helpful. It is always nice to hear from another Cometition Yellow LT4 owner. You may be aware, but these were very low production, with around 140 Competeiton Yellow LT4s produced. Is yours a coupe or convertible? You can see my playlist with quite a few C4 trivia and how-to videos here - maps.app.goo.gl/mphDKMF6QsB4ovhp8 Let me know if you need anything else, and welcome to the club👍.
I Watch the digital guage because it’s supposed to be more accurate then the physical guage mine seem to be 20-30 degrees off from each other manual running hotter.
Definitely more accurate. There's even an information label on the cluster when the cars are delivered new that points out how the analog gauge is not a linear device. You can see it in this video here - ua-cam.com/video/e1KON6ffXpM/v-deo.htmlsi=JS38G4b-B4Z3AY44
I have an 89 vette and I couldn't get it to run any lower then 235 so I changed the thermostat to A 185 and I wired both fans to one switch and just turn them on once i get going and the engine doesn't get any hotter then 185
Hey Rocket, that's a common bypass, but one you need to be careful about. I can't tell you how many C4s I've dismantled that burned to the ground due to this type of bypass. Usually, it ends up overheating the relay or the associated wiring and catching on fire.
@@VetteSource Sense I wrote that Ive replaced both temp sensors with 185 switches(sensors) and have it wired back the way it was factory so now everything works like it should
wiith the old stock radiator (looked clean but was full of white grains of sand) I user to let engine go up to 237F in city traffic or while driving on a track at that point I would either stopt or drive easily (constant speed say 30mph) but I didn’t drove like that too much because after a few thousand miles the head /or gasket (didn’t open the engine yet) failed. Now with the new engine(383 crate, almost "plug and play", obviously different ECM tune), new champion radiator, I've set the fans 180/185 and thermostat is a 180, as recommended by the engine builder, water stays at 185 regardless of driving conditions 195 for oil on race track so far (3200rpm red line so far but should be good if pushed higher). The new engine with the old radiator was overheating, worse than the stock engine. If you are approaching 212F most likely there will be hot spots inside the engine where water is boiling even if the boiling point is raised (coolant mix/pressure) and you risk warping the heads especially if driven hard. I would set the temps at the optimum for engine longevity, 185 should be ideal. There are flags/scalars for overheating in the memcal binfile that are set too high IMO.
My car runs great, however when it’s hot out and I’m in traffic, the idle goes up and down, and the car wants to move l have to hold it down, lately it’s been turning off!
Hey Arthur, It sounds like you have something going on for sure, but the symptoms you're describing are pretty non-specific. I would recommend taking it by a trusted shop to hook it up to a scanner to see what's going on in real time.
My problem is that the normal heating system works fine until it runs for around 40 min and it can’t go above 40 miles per hour after and it feels like it’s just gonna shut off
It sounds like you may have more than one issue going on there. It would definitely be worth your time to hook the car up to a scan tool to see what it's doing on the first start up and after it goes closed loop. It may give you a starting point to work from.
best thing is to make sure you have a full cooling system, with coolant that has been changed according to manufacturers spec since it will break down and lose cooling efficiency over time
Sounds like you will need to hook it up to a diagnostic scan tool that will provide real-time data streaming. Something is obviously happening once you put a load on the system, and in the absence of a "service engine" lamp you're chasing shadows without hard data.
@@VetteSource that’s the hard part i have no engine light on i have a guy looking at the car now I’ll mention the data stream too him and the car isn’t acting up when he drives it.
This Corvette is one of the most beautiful cars. Do you want to sell it because I have been searching for a long time and I am serious about buying it if you like?
That's pretty warm, considering the boiling point is 267 degrees in a closed loop coolant system. On the freely. You should see temperatures between 195-210. Probably best to examine closer if it's staying that hot.
@@VetteSource I also have a 96 and I leave the AC on year-round and the car runs much cooler, The first time I took the top off and shut the AC off I thought it was overheating and stopped the car and started looking for the problem. I didn't find anything and continued to drive back home. I then got on the computer and read about the reverse cooling system and how it always shows hotter than most cars because of this. I did replace the left side fan because it was always running slow and that fixed the problem of not speeding up when it should have. I noticed that when driving with the climate control (CC) on the car runs a lot cooler down around 180-200 so for peace of mind and I live in California I can run the CC year around. The right fan seems to be always running with it on. Good info for those who are not used to the LT engine reverse cooling system.
Yep, that sounds about right. You may have noticed, but when I first jumped in the yellow car towards the beginning of the video, it was running around 200 degrees with the AC engaged. It only got to the higher temps once I shut the AC off. Thanks for sharing your experience, that's good information for everybody to have👍
Yep. I believe the F bodies were designed to run a few degrees cooler. In addition, they have both electric cooling fans wired in parallel, so they both run at the same time either low speed or high speed with AC on. Thanks for the comments👍
When first got mine a 1995 the temp got to 236 in traffic I freaked out and got on the interstate and it cooled,done done some research and discovered they are designed to run like that now I’m at ease with it.
Yea, that can be a nerve wracking experience the first time you see. Once you realize it's perfectly normal, it's a big relief.
@@VetteSource- there's nothing "normal" about it! Chevy....
@@mhicks5008it’s normal….. relax
It is normal but i still dont like it
@@User-1683x2I don't either makes me think the damn thing is going to start smoking.
As long as you're moving, temps stay normal. But if you're in bumper to bumper traffic around town on a hot afternoon, things might get bad lol.
Exactly, it's the time sitting in traffic that can cause that stress and anxiety.
That was what I was going for with this demonstration. Even with the cars sitting in the mid afternoon heat, they will perform as designed and keep from overheating as long as the cooling system is functioning as designed.
Thanks for the comments👍
I have a 1988 L98 car, and I've researched this issue thoroughly. The 1992-96 LT engines are fundamentally the same. Notably, the LT engines have a 'reverse flow' cooling system but, as you showed, the factory temp specs are the same.
Traditionally, small-block Chevy engines were set to run at roughly 180F. As you said, additional heat reduces hydrocarbons before the exhaust gasses reach the catalytic converters. So the extreme temperatures in the engines of this particular era were a factory 'trick' to pass emissions. The coolant passing through the throttle body is only intended to prevent icing in extremely cold environments.
The factory 15psi radiator pressure cap raises the coolant's boiling point to 262F, which is why temps of 217-230F are sustainable. The factory thermostat opens at 195F, so it stays open all the time once the engine is at operating temp. That's why installing a cooler thermostat never makes any difference.
Clearly, the engines can survive long-term at the higher temps. With proper maintenance, they are good for around 200k miles. However, you can extract a little more power (maybe 5-7 HP) from bypassing the throttle body (an easy mod), thereby reducing intake air temperature.
To significantly reduce real-world coolant temperature, you'll need a higher capacity radiator, a cooler thermostat, and modified cooling fan on/off settings, but there are related issues. The engine management ECUs of this era had fixed maps for fuel mixture and ignition timing, with little or no ability to 'learn and adapt'. So lower baseline coolant temperature may actually decrease power output by causing the ECU to use an extra-rich, 'cold engine' fuel mixture and timing map. The extra-rich mixture may, in turn, 'wash' oil from the cylinder walls, accelerating wear. Finally, all the factory-set internal engine tolerances, such as ring gaps and bearing clearances, are affected by temperature. That being said, you can get aftermarket ECU chips specifically tuned for lower coolant temperature.
One thing most people overlook is that the center section of the front air dam loses its proper shape over time, reducing the airflow through the radiator while the car is moving. It folds down and back. Also, that cooling intake sucks in a lot of debris like leaves and plastic bags, which block airflow through the radiator and AC condenser.
Michael, excellent writeup and information regarding the cooling systems for the C4's. Like you stated, bypassing is an option if an owner is uncomfortable with how hot their C4 is running, but beware of the unintended consequences of deviating from the factory settings. Thanks for taking the time to share your knowledge with everyone
@@VetteSource
Thanks VS.
The throttle body coolant passage is only there to prevent icing of the throttle body; it has no engine cooling effect. But I do take your general point, and I've previously given that a lot of thought.
There is an air temperature sensor in the intake plenum, which helps the ECU choose the appropriate fuel/timing map. A cooler reading from that sensor equates to cooler ambient air. Since intake air temp is a fundamental and immutable factor in combustion characteristics, it's a prime determinant for the ECU, not to be ignored under any circumstances.
The throttle body coolant passage does have significant control over TB temperature, but does NOT have absolute control over intake air temperature. Ambient air temp, TB temp, and plenum case temp combine to create a net actual air temp inside the plenum.
I'll try to illustrate why bypassing the throttle body coolant passage is safe under most conditions, but not all possible ones. At one extreme, perhaps you're in Canada in January and the ambient temp is -40F. Combined with the warming effect of the TB coolant passage and plenum case temp, let's say net plenum air temp is +80F. The ECU has a map for that. At the other extreme, perhaps you're in Death Valley, the ambient temp is +120F, and the net intake air temp is +210F. The ECU has a map for that as well.
Bypassing the TB coolant passage and reducing net plenum air temperature simply causes the ECU to select a different air temp factor for its calculations, which it is perfectly capable of doing over the widest expected range of net intake air temps.
If TB temp dips below +32F, there is a very real risk of ice forming inside it, the severity of which is determined by incoming air temp, duration of exposure, airflow volume per unit of time, and the humidity level of the incoming air. This is why the factory incorporates the TB coolant passage. But, given that the TB is attached to a hot engine via the intake plenum, icing is unlikely under all but the most extreme conditions.
While there is obviously a coolant temp sensor connected to the ECU as well, the expected range of normal operating temperature for mapping purposes is predicted to be between +195F, at which the thermostat opens or closes, and the fan-controlled max of +230F. Coolant temp is mostly a pass-fail factor based on whether the coolant and oil are above or below +195F. Below +195F, the engine is considered to be 'cold'.
There are, of course, some 'gray areas' involved in all of this. Welcome to the realities of managing internal combustion engines over an extremely wide range of operating conditions. Contrary to popular belief, the factory really does have a clue about what that requires.
Whew! OK, if all that doesn't cover it for someone, I guess they'll just have to attend automotive engineering school.
Very well said. I'm surprised you don't have an automotive channel yourself, you've got quite a bit of good knowledge to share👍
@@VetteSource
Thanks again. I have thought about starting a channel, but I'm aware of how much time and effort that can require, and I already have a lot on my plate.
For sure, it's quite a handful to add to an already busy achedule. I appreciate you taking the time to contribute here👍.
Wow!! Perfect video for my Saturday morning. Felt the same excitement like looking forward to motor week as a kid every Saturday.
Thanks Muhrad, glad you enjoyed it buddy👍
Really good demonstration. Just to add a little to the already great comments on this. The very early C4s ran even hotter. I have a 1984. When you look up the service information in the manual the temperatures that it gives for the fan cycle are not correct. If you look into the electrical manual for that year it gives the correct closing temperature for the cooling fan switch. Are you ready. The correct cooling fan switch closing temperature is above 238 F. If the vehicle is sitting still that is when the cooling fan will turn on. It will turn off at about 221 F. This was true of the early model C4s. Starting in 1985 there was the standard cooling system and the heavy duty. The heavy duty had an auxiliary cooling fan but again the fan did not turn on until, you guessed it 238 F or above. By 1987 the control of the cooling fan switch closing temperature was changed to above 228 F. This change allowed the system to operate more in line with what was demonstrated in this video. I worked on these cars under warranty and it was very difficult to explain to customers there vehicle was working as designed. Those of you have commented on this are exactly right. The running temperatures on these engines was necessary to accomplish more complete combustion during idle and to optimize the catalytic converter efficiency. Yes, I saw a lot of stupid stuff done to make the cooling fan run all the time, and yes I saw some fires as a result of it. You folks all have done your research. Good comments
Randall, thanks for sharing your personal insight from the field. That's the kind of valuable real world information that's gold for a new generation of Corvette owners working to keep these now classic Corvettes on the road.
Considering how thorough GM likes to be in regards to the mechanical side of the cars, you would think they'd have done a better job communicating the normalcy of high engine temperatures to the new owners.
However, I think the aftermarket Corvette suppliers are partially to blame with all the cooling fan bypass kits they were hawking during the 80's and 90's to make your car run cooler and more "efficient". Once they started advertising those, the urban legend of "your Corvette runs too hot" spread like wildfire.
They should see how hot early 427 big block Corvettes like to run😁.
Excellent information the both of you. Understanding all of this, are there any advantages to "try" and run the system cooler if emissions are not a concern, say with no cats? Horsepower wise?
I found when I bought my 95 LT1 6-speed that she was heating up faster and too slow to cool. I went under the hood with a flashlight and saw the front of the radiator was packed with leaves, as these cars are road vacuums. Cleaned them out and she ran much cooler. Just a word of advice, check the front of your radiator.
Mark, good point. Thanks for sharing with the group👍
Enjoyed the video, very informative. I can now drive around on a hot day and leave my Valium at home. I could not get used to seeing that temperature up that high BUT it's true no lights came on and it never overheated. Getting used to it now. Love my C4 !
glad you enjoyed it. You're definitely not the only one. Quite a few C4 owners suffering the "temperature gauge" anxiety disorder
Can I drive to Georgia from I Illinois at temperature 200?
@@kennygibbs9627 It won't stay that high all the time. Usually on idle it goes up.
@Steve-xf4uv drive around town, it runs at 190 .
Sure, that's perfectly in the normal operating range.
This helps a lot. I just got a 90 and the temp gauge always gave me anxiety with how high the needle gets.
Glad to hear, it's one of those things to get nervous about when you don't have a frame of reference of the normal temperatures to work with.
@@VetteSource Having such a narrow normal range on the needle is strange for how hot these run. I watch my temp on the digital now knowing where it should be.
Yep, the analpg gauge is almost worthless in my opinion unless you just like to be stressing out over where it's sitting😁.
Thanks so much for video. The analog gauge was definitely concerning to me the first time I saw it get so close. 2 years with the car and I’m a lot more used to how it runs.
No problem, glad to do it👍. I found myself having to revisit the service manual to make sure I wasn't losing my mind when I noticed the gauges juat about being pegged out.
General motors needed a way to get the EPA off their back so they can sell some cars and getting these cars to run hot was the answer to passing the smog test. If I'm not mistaken my car comes with a 185 thermostat, that's the temperature the LT1 is designed to run 80% of the time. setting in a traffic jam at letting your car bake at 220 to 230 until you get moving has absolutely no advantage but a disadvantage regarding long-term unnecessary wear to your engine and all components connected to . I suspect that's why these cars love alternators/batteries. Its not good on not just the engine but the components bolted to it including the transmission. heat is the enemy to any engine. It also puts unnecessary coolant pressure on your coolant system causing components to fail in which otherwise never would have if it was running at a lower temperature/pressure, That's why most of the time your plastic sides of the radiator will blow out when you're running hot. it also puts on necessary strain on your heater core. The piston rings in the small block Chevys are just like any other internally that's why a lot of these Corvettes have that poof of smoke on startup caused by excessive heat on the valve seals. Call summit racing equipment tech department or jags high performance and they will refer you to a kit that's designed to convert your existing system to run cooler. Don't run these fans on a manual toggle switch or wire them straight to the battery you're just asking for trouble. do it the right way and you will have a car that runs 185 and will never run past 210 no matter how long you set. Well that's my two cents everyone can do what but my car isn't running at no 230° in a traffic jam for absolutely no reason other than burning off a little extra carbon. Well my baby isn't taking one for the team.
Great perspective, thanks for sharing👍.
Thanks for a good video reassuring owners about high coolant temps on C4 Corvettes. One thing I haven't seen addressed is to check the accumulated debris on the radiator itself. I bought a '94 Vette that consistently ran hotter than normal. After much investigation, I discovered that there was significant buildup of leaves/debris on the radiator core -- in the tiny space between the AC condenser and the radiator (about an inch in between). As you know, the C4 sucks up leaves and road debris like a great Hoover vacuum -- which is sometimes deposited on the radiator itself. It's difficult to see, but with a good light at the right angle, you'll see it.
The best solution would be to unbolt everything and clean it all out. I was able to attach a toothbrush to a thin stick, which I could use to gently scrape the leaves off fins of the radiator, and clean other areas as well.
My cooling issues were solved immediately.
Yep, good point. Thanks for sharing the information. The cooling systems do a great job at drawing in all that road debris and trash until it affects the operating temperature like you mentioned.
Yep, it is HOT in Houston....braver than I am on letting my '96 get hot....just changed the coolant and what a fun adventure on a warm Thursday in Sharpstown! Previous owner just had straight water in the radiator, so wanted to get the right stuff in the system. Amazing how those cooling fan work just as designed. Great video, your having the same ish that I'm having on the HVAC controller...enjoy!
Oh yea, summertime in Houston. Good idea to get that straight water out of the system, that makes a mess with cars that were originally equipped with Dexcool. Thanks for the comments👍
@@VetteSource the two knock sensors and the bleeder valve were the "hoot" in corvette technology.
Yea, that bleeder valve sure is an interesting engineering solution to removing air from the system. If it wasn't spelled out whilst their purpose was, most people would miss them.
228 is the set point for full high speed fans per the factory service manual. My car hits 228 exactly when high speed fans come on. Mines a 94 loaded admiral blue 64k miles and mint...I'm also the original owner.
Yep, that's exactly in line per the specs in the service manual. Thanks for sharing, love the Admiral Blue cars👍.
I'm also in Texas...would love to do a video with you!
Sounds interesting, just drop me an email when you have time👍
Late to the video, having a 90 with the L98. I had to do a lot of service due to age not mileage. I didn't notice any high temps with the old stuff, when I bought it. It had an oil leak at the rear of the manifold so while fixing that I pull the thermostat. It was a 160. The new was a 195 as per Chevy. So, I expected a higher temp. before the fans kicked on. I replaced the old hoses and cleaned out the overflow tank. Checked all other lines due to the old funk in the anti-freeze. I gave it a good flush before adding the mix of new fluid. The thing I missed was looking at the air intake area before driving, it had fur from someone's pet all up in the driver's side. Vacuumed it out, there was no damage to the fins so on my next test ride things were all good. Still a 205-219 in heavy traffic. But the fans kick on and it drops. Same if just at idle in the driveway for a long period of time. THANKS for showing your temps. Different engine but temps are temps.
Good information. Thanks for taking the time to share👍
C4 Temps are a hot topic! haha I have the secret sauce to getting these cars to operate in factory specs. Good info. -Glen
Thanks Glen, appreciate the feedback. Whenever you have time you'll have to share with the audience your "secret sauce" method.
@@VetteSource here ya go..works like a champ.
ua-cam.com/video/8K7iJeOjkBE/v-deo.html
Whats the secret ?
Thanks just got a c4 88 definitely needed to Know what was the coolant temp max and regular degrees
No problem, glad it was helpful👍.
were like this to meet emmisions, thats why the run hot.Nice c4's
Thanks, Giorgio👍.
Great advice on the c4 cooling 😎system's there known for running 🏃♂️hot 🔥🥵😉thank's Dave from Michigan 👍
Hey David, glad you enjoyed it. I'll bet your enjoying cruising those scenic roads up there right now 👍.
i got a 97 TA with the lt1 .. when i got the car it ran 220+, i installed a 160 thermostat and wired both fans with relays and fuses so the left fan comes on with the key and the right fan is on a toggle ... the car runs 180 in stop and go traffic and then drops to 160 on the highway ... these motors make better power at a cooler temp than the factory set them up to run
that's a popular modification, but be sure to watch your wiring modification. I've dismantled several cars that burned to the ground from the relays overheating after that mod...
Ok, mine unmodified LT4 runs around 210 while driving but get up to 230 in idle or at a stoplight. Clearly that’s set from the factory. The issue is that temperature at a stoplight has nowhere to escape under the hood and it puts a ton of unnecessary strain/melting heat on those 27+ year old little plugs, wire connectors, electronic components, gaskets etc…. That’s the crapper about that high temperature on these. So better keep moving in these folks!
Thanks for the video Sir!
No problem, I'm glad you enjoyed it. The deteriorating underhood plastic is a real issue on these cars of the 80's and 90's. It definitely makes it a bit harder to keep them on the road, but it's worth it with as much as they are to drive👍.
Clogged between condenser and radiator with leaves, needles etc will cause high temps. Replace stock radiator with aftermarket with increased cooling. Fans come on at 226, off at 215. Since new radiator our 89 hasn’t kicked the fans on since.
Good advice, thanks for sharing👍
It's insane how hot GM made these engines!! I put a 160 thermostat with a manual fan switch, cruising with air flow it runs at 165!! A couple years ago I moved to Florida and I couldn't take the heat!!! I was there for about 10 months and hightailed it back to Oregon!!! Lol but I will say Florida has to have the most corvettes than any other state!! Guaranteed fact! Lol
Funny, that is the truth. Everywhere you look in Florida you're likely to spot a Corvette. There are quite a few of them here in Texas as well, but there's so many roads it's easy to miss them cruising around.
Nice research and information. I ended up installing a triple core radiator, adding Greenwich hood vents along with a larger front spoiler, 160 Stat, and setting my cooling fans to kick in at 170 and 180 degrees respectively. I run a 38350 FiTech software system to control the 427 blueprint SB engine. Before I did all of the cooling work, the engine would smash 245 degrees in a few minutes in traffic. Now that it's wintertime, I can't get above 150! Well, I won't drive her until April again anyway! Thanks for the video.
Great, I'm glad to hear you found it helpful👍. Sounds like yours isn't very close to stock, so those mods to your cooling system would be called for.
Great and informative video. Keep them coming.
Thanks, will do!
I feel a bit better now. Thanks
No problem, glad to help👍
I really appreciate this video, gives me much more confidence that my 95 car can take care of itself. Would love to get your take on the transmission temperature as well. My fans kick on and bring the coolant temp down pretty quickly, much like you showed here in the video. If the car is moving, the coolant will go from 230 to 185 in a matter of minutes. But, my auto transmission temperatures are really slow to come back down by comparison. Is this typical?
Glad to hear you enjoyed it👍. You know, I completely forgot about the auto transmission temp gauge on the later C4's. Normal cruising temperature should be around 180-200, higher in town. The temperature will come down a bit slower simply because the transmission cooler is only receiving indirect cooling from the fans due to its location in the radiator tanks.
So true, I remember the 427s as well.
For sure, the closest you'll ever get to driving around inside a pizza oven during the summer🤣.
I disconnected the coolant temperature sensor switch, Tricks the computer into keeping the primary fan on all the time & keeps the engine cool.
Interesting, hadn't heard about that hack before. Thanks for sharing👍.
Thanks Mark
Yeah I just bought my 93 and I’ve noticed Going down the highway is about 200(with the AC off) but as soon as I get home and I by time I get into the garage it’s at about 240!!
But if you notice the clamshell is a terrible design! They stop making the functional “gills”that were actually here extractors like the C3 models so there’s no way for the hot air to escape!!
Yep, the c4 front end doesn't lend itself much to cooling if anything gets in the way or there's a blockage. The cooling system was tough for Corvette with the introduction of the C3 in 1968 all the way through the C6's. It wasn't until the fish mouth debuted on the C7 that the cooling system received some extra help.
@@VetteSource yeah exactly! GM should of put more of a cold air induction system in it!
And heat extraction system in place for at least the C4! But I thought like the C3 generation they had a better system but I don’t much about them…I’m not a fan of the C3 generation!!
I have a buddy whose owned several C3’s(heck still has a ‘68 L88 427 4spd sitting in storage!) owns a 94 C4(owned a ‘84)
Owned a’00 C5!! He can tell me everything he knows about them…I just keep forgetting to ask him!!🤣
Sounds like a nice collection your buddy had. I am a fan of the C3's myself. There seem to be a few of them laying around here at the shop😁.
I have 1993 stock 90k miles my temp runs around 140 to 150 while driving freeway in temp about 80 to 90 for approximately 60 to 90 minutes when I get in traffic jams or sit at drive through 180 at tops, but I'm running antifreeze not distilled water which I would only do in emergency situations.
That seems to be a bit on the cool side, unless you're in a cooler part of the world with mild summers. Do you know if any previous owners made some modifications to the cooling system?
@VetteSource I don't know, but like I said I run antifreeze and drive 90 minutes at a time in 80 degrees temperature always temp gage rarely goes past 1st line which I'm calling 140 unless I'm in heavy traffic which is almost never I drive at either 10am or 6pm Midwest state. This car is just for fun and it wouldn't be fun if it was always running hot or if I'm worried about it running hot while I'm driving it.
Ok, 80 degrees ambient is a cooler temperature for sure than what we see down this way. One thing to consider as well, is that the needle garage on the dash is fairly inaccurate, as pointed out by GM when describing it as a non-linear gauge😁. The best read of your actual temperature will be the electronic reading that can be accessed by pressing the "gauges" button on the DIC
@VetteSource I used the numerical temp gage that you mentioned and I didn't know I had lol and my readings are 179 t0 183 while cruising and 194 while sitting in traffic but this is in 80 degree temperature in Midwest while driving about 75 to 90 minutes almost everytime thanks for the info.
thanks ive been tripping on my c4 cooling temp its always on the edge
No problem, glad I could ease your mind👍.
easy to ground the fans with a switch, 165 deg stat. My 92 runs at 180-190 degrees.
Hey Rocky, thanks for the comments👍.
I've seen quite a few of those conversions done and dismantled quite a few C4's that burned to the ground because of it.
Unless it's absolutely necessary, I always advise people to stay away from grounding the relays. It's an accident waiting to happen.
I have a 95 Corvette and mine was running hot and and I was told to replace the radiator and thermostat.... But first check your radiator in front and all the leafs and debreeze get hung on front of the radiator so that's what I did and mine I climbed under front of car and hosed it with water hose fixed it itself runs normal...Then when I replaced my air filter I seen it would have been easier to hose it off from there ((But DO NOT get water on your engine)) just hose off the Radiator...
Great suggestion, thanks for sharing👍
my 1993 runs the same temp too/ great video
Thanks, man. I think it came well, just not as much fun to make it in the heat😁.
The analog gauges are not linear but they are good enough near operating temperature. The position of the sensors is different, in the cylinder head so they want you before. If you needle goes to the hot side it's clear the car is overheating, in the middle you know everything is good.
Yep, I've mentioned that they aren't linear in a few of my videos. With that being said, the analog gauge really isn't your best indicator for actual temps. Using the "gauges" button on the DIC switch to select " Coolant Temp" displayed under the speedometer is the most accurate indicator, as it uses a different temperature sensor than the analog gauge for its reading.
I don't mess with that bad design. I replaced the plastic radiator, water pump, coolant tank and thermostat when I bought the C4. The 200+ thermostat was replaced with a standard 180 degree GM thermostat. Cat runs normal and fans seldom activate anymore. Passes smog check ok. Runs cool.
I'm not so sure I'd call it a bad design, but they definitely left room for owners to upgrade to their personal tastes. Thanks for sharing the info with the group.
My base model 1984 goes up to 125C real fast .. goes down to ~74C when I've got air going through the car down a road. That's like 260F hot
That is pretty warm. I'd check that radiator inlet to make sure no trash is blocking the airflow.
This was very helpful
Great, glad to hear it👍
Nice video:) recently drove in hot weather and when I parked I lost a lot of coolant, coolant was boiling and overflowing at the little white reservoir at the front right. What could be the reason for this?
Hey Erminio, glad you enjoyed it. The cooling system in your car is a closed pressurized loop and is designed to raise the boiling point. When you have a situation like you're describing where it boils over, that means the system has been compromised in some way, like a leak, hole, or possibly a damaged head gasket. You will definitely need to investigate further, but be mindful of the hot coolant and how quickly you can be scalded.
Thanks for getting back to me, appreciate it! The overflowing is happening at the reservoir, could that really mean I might have a bad head gasket?
thanks so much for the video I guess my car is running normal
Thanks for the feedback Bill, glad it was helpful for you.
now shut the air so the aux fans don't stay on.put the car in drive so the idle is lower. take the car out of your driveway and sit yourself in rush hour traffic fifty miles from home. . your temp gage is bordering on 229 and your stuck in the left lane on a three lane highway and nobody is moving. one other thing. your cell phone is dead because the cigarette lighter is burnt out and didn't charge your phone. now you have your test !
You must not live in Houston during the summertime😁.
@@VetteSourceI don't drive mine during the summer. Too many stupid people that can't drive and I like driving in the fall and during spring.
I’m confused. You say the left fan is for normal and the right fan is for when the AC is on. I was under the impression that the three relays for the 1996 fans were wired to switch between a series and parallel arrangement to go from low speed to high speed?
You're thinking of the fan operation on the f-bodies. They both run at low speed during normal operation, and high speed with A/C on. The C4 Corvettes run one fan high speed for primary, and the second fan comes on with the A/C
Appreciate the video.
No problem👍
Que tal amigo buenas tardes! Tengo un Corvette c4 1996 pero se calienta hasta los 240° F, que es lo que puedo hacer?
¿Estás viendo 240 grados en el indicador del tablero o en el indicador electrónico ubicado debajo del velocímetro?
Hey man . Hope all is well . For the zf6 Tranny...i wanna change the fluid on my 96 lt4. Seem to get multiple answers on what type of fluid to use . You know your shit what fluid should i use in your opinion??
Hey Steve believe it or not the ZF was filled with 10W30 engine oil from the factory.
Nowadays, there are several vendors making replacement oil for the ZFs including Amsoil and Castrol. These will be in the range of 10W60 and specifically designed for the ZF gearboxes and specify "synchromesh" fluid on the container.
I can see the leaves on my radiator. How could I get them off w/o takin anythin apart
You can just reach in and pull them off. It's a tight squeeze, but there should be just enough room to get your arm up there.
This can also apply to the 3rd gen Firebirds and Camaros. Nothing grinds my gears more than the know alls in fb groups and the 3rd gen forum who say your car is running too hot or overheating if it's getting up to 220°, it is exactly what they're supposed to run at.
Glad to see you back working on the formula too 😄👍
Hey Chris, thanks for chiming in. The temperature urban legend is one that definitely will not go away. Glad to be getting some time to wrench on the Formula myself. It's time to put the red down for paint, so I need the yellow one to cruise around in.
@@VetteSource correct, I think as long as these cars are around that argument will be too 😄
Well no matter which one you pick you'll be cruising in style!
how does the fan know when to come on what controls the switch? is it possible to put a switch in the turns it on a little sooner like at 220 or something?
It's controlled by the ECM internally, so there's no real way to adjust the setting.
@@VetteSource is there any kind of aftermarket relay that can turn the fan on if the engine gets over 200?
Not that I'm aware of, but somebody may offer one that will interchange with the factory relay that will kick the fans on earlier.
@@VetteSource that would be good. I hate running so hot.
My 96 C4 in the summer (in Houston TX) with the A/C on during stop & go traffic would always overheat!
Hey Michel. Do you mean it would reach over 262 degrees and boil over? Sounds like you may have had a cooling system or electric fan issue.
@@VetteSource The needle would go all the way to real hot though there was no boil over. However, I got rid of it because it started to leak oil then finding out Chevy used silicone as a sealant around the water pump, distributor and bottom pan which dried out over time. The car was 3 years and 2 months old. Chevy knowing this was a problem didn't stand behind it. I sold the car and swore I would never buy a GM product again of which I haven't though I do miss the Corvette.
I understand, Corvettes of all generations are somewhat high maintenance. If you're trying to use as a daily, it's hard to ignore all the little annoyance items like leaking targa tops, squeaks and rattles, computer problems, paint issues, and random component failures that sometimes force you to leave it parked in the garage for weeks on end.
However, when your behind the wheel and it's running well, you'll easily forget everything that annoyed you about it in the first place😊.
Another big problem is there temp gauges are off, if you data log you will see more accurate temps than what your gauge shows.
Yep, that analog gauge on the dash is as close to a modern day idiot light that you'll find. When these came off the assembly line, there was a sticker placed on the cluster explaining that the temp gauge was not linear, so in other words don't rely on it for any degree of accuracy.
I should have had my MT2500 hooked in as well to show the readings from the ECM, but forgot to bring it out.
nice video. Are the Zr1's any different? I dont think???
That's correct. The temperature and fan on/off settings will be the same.
Have you changed the thermostats at all?
Nope, these cars are both completely factory original. I also have a 1993 40th Anniversary with 27K miles on it, and it follows the exact same temperature pattern.
I have a 96 lt1 I just purchased , did not run , I put in a new fuel pump , opti spark , and waterpump , starts right up , my issue is the coolant fans run constant after starting and I have no heat , any thoughts , I also changed the coolant ect switch in the waterpump
Sounds like somebody direct wired your fans so they would run all the time rather than address any problem that may be present with proper fan operation. This is a big no-no. The relays were not designed to be delivering constant current to the fans and can overheat and catch fire. I've dismantled many Corvettes over the years that had burned to the ground from this modification.
Question I own a 1990 c4 with a 6 speed manual transmission I recently replaced the clutch but I was told that the dual mass clutch is no longer produce so it was replaced with a single mass now my car sounds like a Mack truck, it’s there anything I can do regarding this noise. Thanks
Good morning Abel,
Unfortunately the lack of the dual mass flywheels has created the problem you're describing with ZF equipped C4's once the original dual mass is replaced with the single mass.
From what I understand, there really isn't much to do about the excessive noise, as part of the dual mass flywheels original purpose was to dampen clutch chatter.
At the very least, I would double check tolerances between the flyweel and clutch disc to make sure everything was installed to spec.
If you also have your original dual mass flywheel and its not damaged,, you could try having it resurfaced by hand. It's a tedious process, but some people have resorted to that so they could keep the dual mass setup.
Good info!!
Glad it was helpful!
Well I got stuck in traffic for the first time today in my 96 Collector's Edition my temp got up to 243 and I just about lost it. Just being honest I'm not ok with this.
Yes that's the electronic digital gage in the center of the dash. That analog gage is junk even though it works like it's supposed to. Just like your car's mine is 100% stock. Nothing but the oil and battery has been changed.
Yea, 243 is a bit too high. Was that the temperature indicated on the electronic display under the speedometer?
I would look underneath the car in front of the radiator to make sure you haven't sucked up a plastic bag or other debris that is blocking the airflow. I would look at the coolant reservoir level also to make sure you're not experiencing a small leak somewhere.
My problem on my 95 is fans kick on when engine starts and stay on till i turn car off ,any answers ?
Sounds like somebody hot-wired your fans to run all the time with ignition on.
Check the fan relays mounted on the driverside of the radiator/cooling pod, directly above the frame rail. I'll bet you'll find an extra 12V wire jumpered in there to force the relays to run the fans all the time.
Just because GM made them run hot to meet emissions doesn't mean that is optimal. I have a built 85 that runs at 180 on a holley ecu. My son has a stock 89 that runs at 195-200 with a few cooling upgrades, & chip reflash. Letting the cooling system run over 220 is unnecessary.
I would probably disagree. The computer controlled stock fuel injection system from this generation is designed to burn as much fuel as possible during the combustion process, with the excess being recycled back to the tank through the return line.
When you lower the operating temperature of the engine, you may feel more "seat of the pants" power, but it's not as clean or efficient of a burn and tends to foul up the associated fuel injection components and sensors which over time just leads to more maintenance and $$$ spent fixing it.
Figure that the GM engineers spent literally thousands of man hours getting the system perfectly balanced between power, fuel economy, and emissions output and you can see why they specified the operating temperature that it runs at.
Thanks for the comments👍
@@VetteSource I'm ok with disagreeing on this point. I do appreciate the videos.
No problem at all. I'm always appreciative that you guys enjoy the videos and take the time to comment. Just to clarify, I don't think it's always bad to adjust the coolant temperature to what your comfortable with, but I usually aim these type of informational videos to my viewers that may be more driver orientated Corvette owners than gearheads.
I know my fellow gearheads will always find a way to make their car faster, it just gives us an excuse to wrench on them more😁
Have a great week👍.
I'm a first time C4 owner. It's a '96 with the LT4 in yellow. I was questioning the same thing about temperature. I was worried but now I'm not. Any more tips for me is immensely appreciated. Thank you.
Hey James, that's great! Glad to hear the video was helpful. It is always nice to hear from another Cometition Yellow LT4 owner. You may be aware, but these were very low production, with around 140 Competeiton Yellow LT4s produced. Is yours a coupe or convertible?
You can see my playlist with quite a few C4 trivia and how-to videos here -
maps.app.goo.gl/mphDKMF6QsB4ovhp8
Let me know if you need anything else, and welcome to the club👍.
I Watch the digital guage because it’s supposed to be more accurate then the physical guage mine seem to be 20-30 degrees off from each other manual running hotter.
Definitely more accurate. There's even an information label on the cluster when the cars are delivered new that points out how the analog gauge is not a linear device. You can see it in this video here -
ua-cam.com/video/e1KON6ffXpM/v-deo.htmlsi=JS38G4b-B4Z3AY44
I have an 89 vette and I couldn't get it to run any lower then 235 so I changed the thermostat to A 185 and I wired both fans to one switch and just turn them on once i get going and the engine doesn't get any hotter then 185
Hey Rocket, that's a common bypass, but one you need to be careful about. I can't tell you how many C4s I've dismantled that burned to the ground due to this type of bypass. Usually, it ends up overheating the relay or the associated wiring and catching on fire.
@@VetteSource Sense I wrote that Ive replaced both temp sensors with 185 switches(sensors) and have it wired back the way it was factory so now everything works like it should
Yep, that sounds like it should work👍
Wow my Vet Can run Hot...
But my BMW would be Dead....LoL..
Good one😁
do you run with 50/50 mix in the radiator ?
Yep, that's my normal cocktail since we don't get too many hard freezing events this far down in South East Texas.
wiith the old stock radiator (looked clean but was full of white grains of sand) I user to let engine go up to 237F in city traffic or while driving on a track at that point I would either stopt or drive easily (constant speed say 30mph) but I didn’t drove like that too much because after a few thousand miles the head /or gasket (didn’t open the engine yet) failed. Now with the new engine(383 crate, almost "plug and play", obviously different ECM tune), new champion radiator, I've set the fans 180/185 and thermostat is a 180, as recommended by the engine builder, water stays at 185 regardless of driving conditions 195 for oil on race track so far (3200rpm red line so far but should be good if pushed higher). The new engine with the old radiator was overheating, worse than the stock engine. If you are approaching 212F most likely there will be hot spots inside the engine where water is boiling even if the boiling point is raised (coolant mix/pressure) and you risk warping the heads especially if driven hard. I would set the temps at the optimum for engine longevity, 185 should be ideal. There are flags/scalars for overheating in the memcal binfile that are set too high IMO.
237 is a tad high. 230 should be your maximum upper limit if the system is operating correctly.
I don't know why I am here, I don't own a Corvette, but thanks for doing this
Yep, the YT algorithm works in strange ways for sure. Maybe you're destined to have a Corvette in the future😁. Thanks for the comments👍
@@VetteSource I see a lot of them at work, maybe I'll impress someone with this new found knowledge someday
There you go. Nothing like having a ready made conversation starter👍.
My car runs great, however when it’s hot out and I’m in traffic, the idle goes up and down, and the car wants to move l have to hold it down, lately it’s been turning off!
Hey Arthur, It sounds like you have something going on for sure, but the symptoms you're describing are pretty non-specific. I would recommend taking it by a trusted shop to hook it up to a scanner to see what's going on in real time.
My problem is that the normal heating system works fine until it runs for around 40 min and it can’t go above 40 miles per hour after and it feels like it’s just gonna shut off
It sounds like you may have more than one issue going on there. It would definitely be worth your time to hook the car up to a scan tool to see what it's doing on the first start up and after it goes closed loop. It may give you a starting point to work from.
What weight engine oil do you run on the LT4? Its interesting your low mileage car runs lower oil pressure than your high mileage car.
Just the standard 5W-30. I've noticed the oil pressure variations among the different cars myself...
What can I do in traffic to possibly slow my motor down from getting to hot while driving
best thing is to make sure you have a full cooling system, with coolant that has been changed according to manufacturers spec since it will break down and lose cooling efficiency over time
My 76 would run hotter than my 85. Vetts are made to run hotter and it doesnt hurt it at all
Interesting observation that's overlooked fairly often. Thanks for sharing👍
Mine will hit 225 on a hot 90 degree day in bumper to bumper traffic ever since i changed coolant and put a new WP on it,it wont hit 230
Excellent, that's good information for other owners. Thanks for sharing👍
Should run em at 180°, then heat unburned at 230 in exhaust pipes
that's one way to do it...
My corvette runs really rough when it gets hot loses power runs real choppy like it wants too die it’s driving me nuts . It’s a 1992
Have you looked into the optispark or coil?
@@VetteSource brand new optispark and coil and plugs. The problem seems to be intermittent. And i noticed the car runs rough when i turn the AC on.
Sounds like you will need to hook it up to a diagnostic scan tool that will provide real-time data streaming. Something is obviously happening once you put a load on the system, and in the absence of a "service engine" lamp you're chasing shadows without hard data.
@@VetteSource that’s the hard part i have no engine light on i have a guy looking at the car now I’ll mention the data stream too him and the car isn’t acting up when he drives it.
This Corvette is one of the most beautiful cars. Do you want to sell it because I have been searching for a long time and I am serious about buying it if you like?
👍
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When ur slow its hot 260ishWhen u run it freeways. It stays 220230
That's pretty warm, considering the boiling point is 267 degrees in a closed loop coolant system. On the freely. You should see temperatures between 195-210. Probably best to examine closer if it's staying that hot.
215 f
Good info, thanks for sharing👍
Your LT engine will run cooler with the A/C on.
Yep, that second cooling fan helps quite a bit. Thanks for the comments👍.
@@VetteSource I also have a 96 and I leave the AC on year-round and the car runs much cooler, The first time I took the top off and shut the AC off I thought it was overheating and stopped the car and started looking for the problem. I didn't find anything and continued to drive back home. I then got on the computer and read about the reverse cooling system and how it always shows hotter than most cars because of this. I did replace the left side fan because it was always running slow and that fixed the problem of not speeding up when it should have. I noticed that when driving with the climate control (CC) on the car runs a lot cooler down around 180-200 so for peace of mind and I live in California I can run the CC year around. The right fan seems to be always running with it on. Good info for those who are not used to the LT engine reverse cooling system.
Yep, that sounds about right. You may have noticed, but when I first jumped in the yellow car towards the beginning of the video, it was running around 200 degrees with the AC engaged. It only got to the higher temps once I shut the AC off. Thanks for sharing your experience, that's good information for everybody to have👍
212 F is BOILING!!! You guys are not correct on this. Sorry.
The boiling point is raised in a closed system. Thanks for taking the time to comment.
I took my car apart for nothing....lol
That just means you've well.on your way to becoming a subject matter expert😁.
My LT1 in my 95 Z28 ran better.
Yep. I believe the F bodies were designed to run a few degrees cooler. In addition, they have both electric cooling fans wired in parallel, so they both run at the same time either low speed or high speed with AC on.
Thanks for the comments👍
i just bought a 87 with 48k on it
Perfect, good for at least another 35 years with that low of mileage👍.