Did Liars and Thieves Misdiagnose this Car or Am I the Bad Guy
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- Опубліковано 1 жов 2024
- 2007 Jeep Commander with misfire issue that two shops were unable to diagnose, but they had no problem finding just about everything else wrong with the car. So the owner brought it to me to help out.
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I've owned a shop for 15 years.
You are spot on. We operate with old school morals and ethics.
I turn away roughly 20 people per day. And my customers won't go anywhere else.
Honesty is easy and WILL make the money flow.
Bravo!!!!!!
Location please
Denver Colorado
Well, compression test you get a very brief blast of air/pressure on the leaky section of the gasket. Leak down test is a consistent pressure being held on a weak gasket.
He’s back !!
God bless you for not charging them, and the good video
There is a better way, but only on cars that support individual cylinder misfire data. You will get a misfire on that cylinder on cold start, most newer cars have a misfire counter for each individual cylinder and that will help point you where you should be doing a leakdown on. If there is no "misfire" data, some vehicles tell you the speed variation of the crankshaft per each cylinder you can go off of that. But older cars you simply won't get that data as it isn't programmed in to tell you what cylinder is misfiring. Relative compression like you said is sometimes fruitless, because a head gasket leaking into a coolant jacket usually doesn't cause a significant loss of compression, its simply coolant being sucked in on the intake stroke.
Your P0307 is basically your pointer already. But sometimes its nice to verify misfire in live data via the counter. Because it won't always trip the code.
Good advice. I am actually aware of this but haven’t introduced concept in videos yet. Maybe time to do that.
Well Matt, I've left you a few comments before. I'm almost 73 now. I have 2 hobbies, watching your videos and bowling. 25 - 300's. Looks like I'm gonna sign up to your channel. Tell me how to enlist. You are the GREATEST. And yes. I yelled " GREATEST " !!!
Hahah thanks so much. By the way I worked at a bowling alley when I was 15. Was there for 13 years. Never bowled a 300. 279 is my best. I never seen anyone bowl 25 300’s but I remember watching a guy bowl a 898 series.
If you put a pulse sensor or a pressure transducer connected to your pico into the coolant neck, you might see a small pressure increase when the bad cylinder is on compression. This should work because you had pressure in there after cranking when you took the cap off. If there is a misfire, you can put them in the exhaust aswell. This would be very helpful to pinpoint which cylinder to test if there was no misfire data.
great recommendation!!!
You got here first. This should pick up the pressure pulses going into the cooling system. Might be more accurate with a pulse sensor.
Please do a follow up if possible. Would be great to see.
Came here to say this too! Sync it with a coil or fuel injector and you can locate the exact problem cylinder. It works with either a regular transducer or a first look type pulse sensor. Super quick, accurate and easy.
@@NZdiagnostics GREAT ADVICE , BUT ALWAYS SINC TO THE COIL NOT THE INJECTOR , INJECTOR FIRE BEFORE AND AFTER INTAKE VALVE OPENS AND CLOSES SO IT'S NOT TRUE TDC. THE COIL TIMING WILL BE MORE ACCURATE.
Matt dropping some red pills in this one. Thieves = admired. Honest = suspicion.
That's how you achieve "equity".
A few suggestions:
For the voltage relative compression test, set the channel to AC coupling, reduce voltage to something more like +/-2V, whatever is suitable. Should make the variations far more obvious.
For the amp clamp relative compression test, use filtering to remove most of that noise. Noise can hide lots of details. Again, AC coupling may also improve the situation, or not - try it and see.
For additional tests, try a pressure pulse sensor or pressure transducer connected to the cooling system. You should see when the cooling system pressure increases = when one cylinder leaks into the cooling system. Add a sync signal from #1 ignition for example and you'll see which cylinder is leaking.
Matt, I agree, when I was working as a tech, my philosophy was always "If you pay more attention to helping the customer than what it pays, your paycheck will take care of itself". My goals were always fixing the car right or leaving it in the same condition it was when it rolled out of the factory.
How funny because I have used a nearly identical version of that with my clients for my real job. “If you take care of your clients, they take care of your numbers”.
It’s a great philosophy! Glad to see someone else who owns it too!!
I think of the car, not who's driving. I think of drivers driving home:)
Should have sent a camera in the bad cylinder , and pressurize the cooling system to see what size leak it was for kicks and grins
Yes a honest person with a conscience. Great job. You make Great videos. You have a wealth of knowledge that you share with us. Thank you.
thanks for the nice comment!
You can’t excuse the shop so easily! All they had to do was what MOST people do when they suspect a BHG, a chemical test. It was obvious
Compression? Or chemical.
I ask honestly cause Idk. But I haven't finished the video either 😬
Oh dear Lord... Never mind. I thought there was some kind of advanced type of chem test. This is very common stuff. My bad. I'd have just done a pressure test to begin with a kit.
Wow, 27 min in. You humored your buddy, proven that a compression test can't always be counted on over a simple code, and so far, shown the most efficient way of where the coolant is really going. Nice man.
Do I have your consent for a brain transplant?? Lol
I've finished. Thx for the video.
No, he has 6 children, he can't afford better equipment. That's the general reality of our modern world.
Okay,I for one would go work for you, resulting in possibly doubling the "doing the right and honest thing". Just saying,you could have a person or two doing the work and making even more people happier and satisfied.
Matt. The reason the compression test lied is the water can not get out of the way fast enough. Cheers Adam
Oooohhhhh!!! that’s a good thought!!
Not blown out big enough
Yes true and is a factor. Water can't be compressed. If there was no water in the system, you should see a difference in the maximum compression reached. The difference may only be very slight, depending on the size of the blow out though.
I used to work for Caterpillar global engine development testing engines. We used in cylinder pressure transducers to monitor cylinder pressure while the engine was running. We did this to monitor knock while advancing timing. Anyways... The pressure developed during combustion is much higher than that developed by just cranking the engine. If the head gasket is minimally compromised it may not show on a simple compression test. Cylinder pressure during combusting will be much higher and be enough higher that it produces the symptoms of a blown HG. I've seen this on diesel engines several times. All the symptoms of a blown HG... Compression test normal. This is even more disturbing since diesel engines typically make in excess of 400psi during normal cranking. I've seen several diesel engines with blown HG run mostly normally and never over heat either. The only real indication is excess pressure in the cooling system. Good video 👍
Love how you’re precise and the fact you’re not trying to mess people over.
VERY SMART MAN
Great video Matt! Flat rate master did a pretty cool video about head gasket testing and he mentioned an interesting method of pressurizing the cooling system and looking in the cylinder with one of those endoscopes for the appearance of wetness on top of the pistons......thought that was a pretty neat idea.
We are both on the same soapbox. I would love to go fishing with you so we could commiserate on just how despicably pathetic society has become. If I have learned anything in my over forty years of spinning wrenches, it is there are no absolutes in this profession. You will eventually run across a vehicle that will make a liar out of you. It's just part of the gig. Great video as usual.
Thanks my friend. If you ever find yourself in Denver let me know!! Lots of fishing here!!
@@SchrodingersBox I’ll certainly do it.
About the test 'lying' - seems to me that if you have a small leak, then that won't show up on the compression test but it can be big enough to let coolant into the cylinder and cause problems there. You only need a few drops of coolant every engine rotation for a big problem, but a few drops of air missing from the compression, you won't notice. Also, applying a denoising (lowpass) filter to the starter waveforms might help a lot, they're so fuzzy now you can't see much.
Awesome video Matt, glad you're back. I always thought that a cylinder pressure test was the answer for compression problems but I stand corrected so thanks again for PROVING it on video and pointing out a better way to diagnose that type of problem. I don't mind putting in the work if the results are correct and by the way I share your views on the current declining status of our American values
So glad to hear - on all counts!!!
Yeah I don’t mind admitting I am wrong and my reliance on compression tests earlier on was indeed an oversight. It can be misleading.
Hey thank you sir I bought xtool it helped me fix a friend's misfire and transfer case encoder motor fix thank you sir 😊!! Fuel trims look 👍
great to hear!!!
To much waffle trying to show how electronics can (or might) diagnose a fault which could have been diagnosed 40 years ago.
How would you have diagnosed this 40 years ago when the cylinder are under the intake?
@@SchrodingersBox We had radiator caps of of various designs made for different vehicles modified with an added piece of 1 inch clear hose/tube about 6 inches long.Drill hole in cap and Araldite tube to cap... Fill radiator and tube nearly to the top of tube making Sure that all air was removed. Kill ignition or injection (preferably both if vehicle has a cat) , Crank preferably at full throttle and if any leakage into cooling system of any CONCERN was apparent the water /coolant would rise IN the tube ..If one was interested to find out which cylinder, remove one spark plug at a time and keep doing test. When the water in tube does not rise (because of no spark plug and thus no compression) that's your cylinder. Best done with hot engine but a bad head gasket would show at anytime.. Cheers from Australia. 75 and retired...
Great idea and advice!!!
Matt, the compression test doesn’t lie…it simply isn’t useful for conclusively diagnosing a bad head gasket. It is a basic test to identify the mechanical condition of an ICE to generate sufficient compression for combustion, nothing more. Coolant leaking into a cylinder (or combustion gases out) can be a trivial amount of loss of air compressed relative to that of the displacement of the engine cylinder…for a 2 liter,4 cylinder engine, 500cc of displacement compressed (on EVERY stroke) relative to what may be a pinhole sized leak in the head gasket. Science. A blow-by (leakdown) test or the chemical test of the coolant, both of which you show, are far better tests for detecting a failed head gasket than using a compression gauge, and are just as fast (or faster). That is the explanation…science.
Last, since you are an educated man, a diagnostic test is incapable of lying. The results provided may be misleading or inconclusive, but lying is the intent to deceive (knowing information is false). Lying requires more than just data or information. Data doesn’t lie…people do.
Agreed. I should say it is misleading but you are right- it is reporting the conpression accurately
You can scope the radiator with a pressure transducer.
oh damn that’s a great idea. dammit I wish I had thought of that. of course this would only work if the compromise was to the cooling system but it’s better than what I did!
@@SchrodingersBox And you could Sync it with spark or Injector or flywheel trigger and see what Cylinder is pushing the Coolant without removeing a Sparkplug for Testing
Totally agree!!
Could it be that compression leaks into coolant system don't show in relative compression waveform because "you can't compress a liquid"?
Perhaps it should be standard practice to remove the radiator cap when performing relative compression tests.
Perhaps even removal of the oil filler cap and a major vacuum line (e.g. brake booster hose).
I absolutely agree that is the best explanation.
As far as Hose building a business. It is possible, but when you start doing more you start paying more. He has got to pay taxes on it before he gets caught, because he want to accept debit cards, and everyone wants to pay that way, and he will get 1099's from his credit card proccessor. If he claims it as income then he has to get a vendors license and start collecting sales tax (a time consuming process in Ohio), before they catch him. Now he has got to do accounting to keep track of all his expenses and billing (more time). Now when he does his income taxes he is going to have probably pay an accountant to do them, I don't but most people will. Then he has to get garage keepers insurance, so if he has an accident driving a customers car he is covered. Then he will have to get general liability insurance if he does mobile work at other businesses. Plus he will want an umbrella policy to cover all those policies. It goes on and on and on....
Totally agree. All the MORE reason he deserves his success and reward and all the more reason people who don’t do all of that are not victims of “misfortune”
@@SchrodingersBox Yeah, a lot of people don't realize the expense and effort you put into you success. In Ohio, it still a crime to steal though, so at least there is that.
Agreed 100%. It also in my opinion explains the dichotomy between the business owner and the unskilled labor. Who deserves to make the bigger share of the profits? Is it the person who built a business out of their garage working 14 hours a day without not even a day off for 5 years, took out a mortgage loan and a business loan in addition to securing capital from private investors, made arrangements with distributers and manufacturers, got insurance, hired employees, hired legal resources, analyzed the market to position for growth, learn antitrust laws, validate zoning restrictions and reinvest for expansion….
Or is it the guy who puts the products on the shelves?
There must be an explanation for this cannot be a miracle.
What is expected coolant pressure especially at cracking vs air (gas) pressure applied to faulty cylinder during a test?
How about slowly increasing applied pressure to see at what force it starts passing to a coolant system. Not every leak must be of same specs - I assume?
There is explanation coming up in a new video and in fact we will even prove the explanation next week.
should have been able to put pressure on cooling system and find water entering cylinder still lots of work would have to remove all spark plugs. i ran into it on my wifes truck 360 dodge would skip every morning for a few seconds had good compression. pulled all plugs and checked one had water in it
Thanks Howard. absolutely would be a valid technique.
Electronics will never in a case like this beat leak down test
Matt, Great video !!…instead of using 20 volts DC for the RC test use “AC Coupling”…change the DC to AC and select a 1 volt scale…the compression peaks will be on the bottom and not at the top as you would see with the AMP clamp setup…have you used the WPS on a radiator for a blown head gasket ??
C5 Diag
Thanks Robert - yes others pointed out the radiator pressure. great idea. I hope with the coolant it won’t damage the WPS- will it??
....it's whatever the DA says it is (regarding the upper limit) because there's no accountability. Look at L.A.? It's gnarly
Hi from the other side of the pond, been in diagnostics since it started, 25yrs, must be mad,
But great approach to the car, but one thing I was thinking is, can you not do a RC test off of the battery directly with the Pico ?
I don't use a Pico, I tend to use my trusty old fluke/tech31 as it has a lovely bar graph for RC tests and just clips on to the car battery?
I'm sure I've seen someone else do something like it in a Pico. Just think it may be more of a delicate indicator if that all makes any sense?
On tech31 it shows all cylinders in % from 100 down .
Sometimes you just can't find what it is, but boy does it get to you not knowing, I love doing autopsies on anything that's failed just to know why.
I started doing that about 10yrs old to mum and dad's black and white TV, I was grounded for weeks. Lol
All the best guys
look inside the #7 cylinder and you will see coolant. the coolant is raising the compression.
That explains it!!
Was compression test done with rad cap off?? Was compression/ pressure being held in cooling system giving false cylinder pressure reading?
Good question. Rad cap was on.
@@SchrodingersBox cooling system could have been buffering/maintaining compression,
Whenever overheating reported friend of mine would always check oil, then take of rad cap and turn over motor, if oil was milkshake and rad looked like old faithful no further checks were needed, not exhaustive or conclusive but with those checks no water pumps ect would be fitted.
Thanks for posting I’ve learnt a-lot from your channel this novel electronic compression test is just one more simple yet genius tip, its great you do good work and share your skills much appreciated, Cheers.
Welcome back, Schrodingers Box
Enjoy your weekend Schrodingers Box
👍
SHARP Schrodingers Box
From Nick Ayivor from London England UK 🇬🇧 ⏰️ 15:51
Knowledge is Power
Just the gasket diagnosis might be good enough without a specific cylinder named. Kinda academic at that point unless you possibly want to do only one head.
Yes I agree. usually once i determine 100% it’s a head gasket failure I stop and call customer
Was the "clean" looking plug from #7 (the cylinder with reported misfire)? If so, might have been steam-cleaning due to the head gasket failure into the coolant passages.... Might have been interesting to see what the top of the piston looked like, as well. Great video, thanks!
Yes but it also was could be clean looking because it only was replaced 3 weeks before while the others were in there 5 years.
No car company has provided more interwebs mechanic fodder than AMC/Jeep/Eagle/Diamler Chrysler-Benz/Fiat. Those 100 dpi images from the shop quote are 😂
Something is wrong...the blue trace should higher if loss compression, but your was lower. Around 25 minutes....Less compression means the less restriction and the voltages should rise. Another thing what entire world make mistake...not removing all variables....spark plugs! Testing 1 by one lead wrong reading...good read only better and bad worse..VARIABLES, VARIABLES, VARIABLES
Completely agree re. the other shops. None of the other crap matters until they've addressed the elephant in the room. Your poor customer would have thrown all that money away and then still be met with the cost of a head gasket repair. Also, for your chef friend, can recommend the HoldPeak 600amp AC/DC current clamp. It's the cheapest one I've found that works perfectly for relative compression tests.
Thanks for the video.
Always assume you're "the bad guy", especially if you happen to be married to a naggy woman
Good work! FYI do the chemical test outside, It will pickup hydrocarbons in a garage & give you a false reading, it’s happened to me
the coolant in the cylinder is displacing air thereby raising the compression
Agreed. That makes the most sense. The coolant can’t leave as fast as it entered so compression isn’t changed.
Had a95 land cruiser with straight engine, I think 4.7. Milage??? Runs nice! Wanted tires but dead battery no start etc.. checked and charged good bat. Slowly cranked key like 10xs and start. In the middle of changing tires, it started , but with a couple high power fans hard to hear. Ran for 20min or so, long story short, unhooked neg batt. Terminal and cranked the key to start to shutt off vehicle to finish. I'm guessing starter but all this happened after fussy customer showed up. So I don't know if they were mad and remote started or problem with what's on car. I think a car problem. Anyways, I will probably never see that car again:(
I wonder if the head warped from an overheat event(s) and yet somehow is less warped when it's at operating temperature vs when cold-and/or expanding metal seals the gap. It seems somewhat counter intuitive, but I"m guessing that warpage, especially after several cycles with different rates of overheating and cooling, is a complex process. However, under higher engine loads the head gasket leaks more at any temperature (white smoke). Also, I know it's crazy, but could coolant somehow be getting into cylinders via the intake?
Saw a 92 accord, no brakes unless you pump, obviously been filled, no visible leaks. Customer says a cylinder issue. I have had a 93 Sanoma...self bleeding:)
You're never the "bad guy"!.
In fact,buy yourself a white stetson.
😀
See,us foreigners do know something about American culture.
Hi Matt, Professional mechanic? Is there such a thing? At what point is one to be considered a professional Auto mechanic? after all you don't need a license like every other trade to become a mechanic! That makes it very easy for ANYONE to become a Professional mechanic/ shop.
Over the years I have been lucky enough to have worked alongside these "pro's". They really could take a test like a champion. You know, the test like ASE and the OEM type tests. Some of these Techs could not fix a sandwich. Don't get me wrong they are good to have on paper but in real world not so much.
I think Clubber Lang would have called them paper champions:)
don't get me wrong, I have known tech's that were super stars in the trade. IIn my opinion you're better off bringing your car to someone that can spend the extra time during a diagnosis (someone like you). These shops don't pay enough to perform Diags on every variable a vehicle may have, nor do they want you to spend the extra time. It's get them in, get them out asap. They also charge double what the guy at his home garage is going to charge.
This message should get the blood going in some:)
on a side note: We miss your troll videos please do more please:)
thanks
Great information, just a guess this has an iron block with aluminum heads and uses a multi layer steel shim type of head gasket. They do this to allow for some movement between different expansion rates of the two types of metal. Gasket may not be blown just leaking, I've had the same symptoms and replaced the gaskets not being able to actually find the spot where it had failed. I always wondered if it would help to just re-torque the head bolts.
The words "Never" and "Always" are 2 of the most abused words in our vocabulary so I'm very careful in the ways I use them. Compression tests never lie. Faulty equipment and/or misuse usually lie. Engine Compression isn't always affected by head gasket issues. It all depends on what part of the head gasket is damaged. It could be damaged at one of the coolant ports and have nothing to do with Compression or cylinder head could be cracked on an area of a coolant port that is not adjacent to the combustion chamber. Most components have several different tests. Therfore just because it passes one test doesn't always mean it's a good component. The only way to pinpoint and verify is to do all the necessary tests. Hey, thankyou for sharing your vast array of knowledge with us while saving us a great deal of headaches and money as well as discovering fascination of figuring out how things work. Your intelligence, modesty, and honesty are an inspiration to me and I'm glad you do what you do. I don't believe that money makes the world go round like they say. I think it makes some people dizzy going around in circles being busy.
Commenting as I am watching. Does this tool show a dead module in the full count of the number of modules or it simply skips over it and not enumerate it like some other scanners do? The reason I bring this up is many folks like to know how many modules are on the car that they will work on so for future videos that you scan with this tool, may I pls ask that you scan the vehicle, get the full count on the first go around, then once repaired to do a post-scan, double check the module count to see if one came back to life based on the repair. Some more expensive scanners have a full count near the top of the screen, dead or alive. An RC Test is only a guide, coolant leaks inward to the cylinder on the intake stroke while compression does not leak into the cooling system strongly on the compression stroke but may leak during the power stroke if actually running, during the test this would be the expansion stroke with no real effect, at least not proven as you did not do a compression test on the radiator which may need a very sensitive tool for the scope, you also did not check for an intake vacuum problem which also needs that sensitive tool. Some head gasket leaks seem to be one way as the blown gasket acts as a one-way flap of broken gasket or something like that, many I have worked on only leak when sitting all night and cooling down and allowing the coolant into the cylinder during the cool down cycle only. Up until 18 minutes, you did not use a sync signal to ID which cylinder in the firing order was the actual low compression positively identified with the RC test, although very slightly. Very likely the oil cap was from this issue but need to know if the owner does regular oil changes and more so do they do a lot of short drives, this will condense water in the crankcase quite easily. To read that spark plug we need to pull 2 plugs to see if this one is washed and the other has black or brown residue as an additional verification. In some cases, the plug will be colored/tinted the same as the coolant. Your second RC test is definitive but imagine the first RC test, where is the compression loss going, its a practically full cooling system, so where is the loss going, it must be minimal, drain the coolant and try it again to see what an installed radiator cap and an installed spark plug with an empty cooling system looks like on the scope. Your scope has the ability to clean up all that red noise, I think with a better/cleaner capture you will see the problem easier, I can see the repeatability on the later tests also. Manual compression gauge, first pulse over 90PSI, no problem with rings, no cylinder washdown based on burning coolant so any other compression leak is small and not noticeable via this method as you have stated. Looks like it is too late to compare spark plugs as the previous shop charged them for work that did absolutely nothing to fix the car, and took away the ability for the next mechanic to see the problem right away, (possibly) BIG SURPRISE. Known good cylinder manual compression also over 90PSI on the first pulse, the ring inspection pulse (if low, do it again as you may have already been on the compression stroke and got cheated out of a full stroke). Cutting their losses can be your honest gain, buy it from them Bro. ON YOUR SIDE HERE, if you saw the original spark plug on #7 and compared it, you would have found the problem ASAP.
Possible mistakes, red waveform too noisy, blue waveform too short in height, only reading one spark plug (no help in this case but you didn't think of it up front), not syncing the amp wave to a cylinder ID like #1 on a second channel, I believe with a better scope setup, you also would have found the exact cylinder ASAP. THUMBS UP
I think you did a great job, and I hope this person becomes a great customer for you in the future. I feel like you do, treat people honestly, you will sleep much better at night. My wife gets so angry with me because at 73 with a bad back and shoulders I do everything myself, I told her "I would love to pay someone competent a great wage to fix things for me , but every time I do that, they do not do the job correctly, or they skip steps for a few dollars and it looks crappy or only lasts a short time.
Just take the rad cap off and crank. No set up needed. Will dx leak into coolant system at least using engine compression already supplied. Obviously not into intake/exhaust/or block. But quick and most common.
Science doesn’t lie. Test evidence doesn’t lie. Problem is test error or analysis error. Cylinder leak has five potential paths; adjacent cylinder, exhaust, intake, coolant, or external. Your test showed a cylinder to coolant leak path as well as did the inspection and as did the operator symptom description. The engine run test showed a bidirectional coolant to cylinder leak path evidenced by the white smoke in the exhaust.
You were experiencing an office effect where source greatly exceeds drain. Not a fault of the tests you selected. Just a fault of analysis. No more of a “lie” than the air compressor pressure gauge lying when the cylinder leak-down tester connected and in use. No more of a “lie” when voltmeter shows battery voltage when a indicator light bulb connected.
Solving a system of equations with multiple variables takes more than one test result value. Measuring gas in the coolant was aggregating, not differentiating when you were looking for evidence differentiating between the cylinders.
A damp cylinder can cause a misfire as exemplified by the well-known Ford 4.6L plastic intake coolant leak into cylinder 1 causing an intermittent misfire that also destroys the cylinder 1 ignition coil and the bank 1 catalytic converter. Looking for an easy test? Since either a damp cylinder or a misfire can cause a lower temperature exhaust, use a thermal camera to look for the relatively cooler exhaust port.
Diagnostic charge? :- )
Don’t say science lies because science never has, just people. Otherwise good video. So the other shops wasted her money so that not enough money was left to salvage the vehicle. That should be a crime.
Ima find it hard to believe 2 shops couldnt diagnose that.Could be a case of a customer concealing information.Indeed you said it yourself,now your armed with the knowledge and expertise you have become the bad guy,as you have inferred the 2 previous shops as being.
The fanciest tool I have is just a fancy code reader that can test battery and alternators and a few other things,
I do have the fluid tester and a test light and a digital multimeter, compression gauge, fuel pressure gauge, vacuum gauge, voltage gauges….. the old school basics. That’s it.
Been fixing my own cars 40 yrs ans now my kids. Rarely someone else’s just cuz it’s a hobby for me and my kids keep me busy enough although at one time it was a thought.
I think it would help some to have better tools but even as a medic I found people depending too much on fancy tools and forgetting the basics.
Our brains are the best computers in the world as we see, hear and feel more than we know but less when we depend on other things.
Those other mechanics have to just be thieves cuz head gasket is the first thought after over heat ESPECIALLY if the car has the positive pressure cooling system without a true overflow as the pressure has to go somewhere and head gaskets are the weakest place.
Thank you for your knowledge and videos.
I watched simply cuz your video randomly popped up on yt and I know you always have good info.
It’s too bad she go treated so bad as a head gaskets are relatively cheap to fix unless things are warped.
Bernie Thompson has a pressure transducer that he uses a scope to measure the pressure pulses in the coolant, then syncs to #1. That may be way more sophisticated than you want to do, because most do-it-yourselfers can't do it.
Small leak, large displacement = little compression loss.
I don't understand why when you give it throttle you get more white smoke....more throttle = less vacuum sucking coolant in..... unless it's when you let off the throttle after pressurizing the coolant with more throttle.
Just because it's a shop doesn't mean they're professionals! What's sad is the fact that they wanted to spend $4000 which would be a complete loss to the customer because the major problem wasn't fixed. The shop just wanted to do easy stuff!
I absolutely agree.
A friend of mine was paid temporarily via a prepaid card and someone from company had access and spent $990 of it and he could not do anything. I agree, California hates hardworking middle class.
Super great video, and I agree with you totally on the problem ,not with society , but with radical liberal ideology. One issue about the video I want to comment about the compression test. The compression test did not lie. It was 100 % scientific. It only seemed to lie based on a preconception of what normally or often occurs with a blown head gasket. Think about what causes the compression gauge to step its way upward.. It measures a spike pressure in the cylinder at the compression stroke. It is apparent that the leak in the head gasket is either not severe enough to allow the compressed air fuel charge out into the coolant passages ,or there is some effect from coolant coming into the cylinder during the intake stroke and effectively raising the compression from some liquid being there. A compression spike from the operation of the piston cycle, is not the same as the constant pressure applied by the shop airline. A graph of the compression pressure would be much different than a graph of the cylinder pressure from the shop air line. The compression test did not lie. The compression test just has to be used with many restraints on what it could or could not represent.
Unfortunately dishonesty in the car repair business has become so widespread that many people simply accept this type of scenario as part of car ownership and simply sell the car as soon as it starts to develop problems. An expensive solution, but the approach of many who cannot or are unwilling to learn more about car repair!
Back to the soapbox--I'm hoping we see a change in the next couple years...
Most of the time a blown won't show relative compression being different because it was most likely a coolant leak into the cylinders
Hi Matt, full radiator, cap off crank engine and look for the bubbles, no tools needed..
the water pump itself often causes bubbles though. I have tried that many times and it’s inconsistent.
also- even if it was a cylinder leak- how would I know WHICH cylinder it is?
@@SchrodingersBox Hi Matt, fair comment, but there's a difference between the more consistent small bubbles of a water pump leak and the surge of an compression leak whether it is from a porous cylinder, cracked head or blown head gasket.The point I was making is that you can use this to get a fair idea of the problem on the side of the road away from home or service centre. As for which cylinder it is you could try leaving the spark plug out of each cylinder in turn and see if there's a reduction in pressure in one or more (adjacent) cylinders.
Well wait-- if you have to remove the spark plug to do that, why not just do a leakdown test to bring with? Also what if the cylinders are under the intake manifold? And also what if the compression loss isn’t to the cooling system- how would that be determined- you wouldn’t know with this test.
A method is needed where you can identify all cylinder leaks and identify the affected cylinder without removing spark plugs.
Super Mario diagnostics did a great video showing how the relative compression isn’t the end all be all solution to mechanical health.
Strange how they did not did the chemical test when there is white smoke. I know it requires some money as you lose the fluid that you have put in the test tube, but disassemble sparks required time and you can damage something.
The chemical test is such an easy test to do. Everyone can do it and you can do it when you want to buy a used car too.
Mechanics don't care or incompetent just send out bills fix it yourself
It's def You ...
Finding all these things wrong. 🙄
That sounds like a no quote. It's like they didn't even really want to fix it
We'll do all this other stuff on your vehicle and if we have time we'll look at the issue you came here for.
hahaha summed it up!!!
....you're the bad guy" ....because somebody's feelings might get hurt.....they need to change their tampon.
Hahaha I love this guy!!!!
Truth!!!!
Existing minimum 7 methods to find that problem...
Hey Matt! What I’ve done in the past is install a coolant pressure tester (cold engine) and leave it (with no pressure) while I crank the engine over just like a relative compression test and if it creates pressure it pretty much guarantees a bad head gasket
Yes I have heard of that too!!
@@SchrodingersBox another thing that I have learned from Eric O. (South Main Auto) and super Mario diagnostics is to install a pulse sensor like the first look in the cooling system and sync it with the relative compression test and and ignition event. You are going to see small bumps on the cylinder/s that may have the leak instead of doing a leak down test on all the cylinders. Personally I have only seen a couple of times since I learned about the test.
Didn’t realize you were making a video about this very test 😅
Hahahaha yes I just did it. Video coming out soon!!
No sparkplug in cyl 7 showed no compression with rc test
Did they not recommend scrapping the car .this is corruption.
For those about to rock….AC/DC Amp Clamp!!!
Coolant leak in the intake is not possible on the 4.7.
yes agreed I looked up later and it’s a dry intake.
Here's your explanation for it. Consider the differential geometry of the cylinder as the piston travels vs the geometry of the leak. Pistons are fast. Leaks are comparatively slow.The compression tests in all forms will always lie in this scenario. Normally a compression test is only a valid diagnostic tool when you are looking for a substantial cylinder failure like a burned valve or a broken piston/ring, etc. A blown head gasket or even a cracked head is NOT a mechanical failure in the sense that a comp test is designed for. You did the right thing. Chem test, pressure back flow test and general common sense inspection. A leak down, removing all the dynamics of engine operation from the equation is great.. Even that however does not diff between a failed gasket and a cracked head/block. Some times a wet pressure test from the cooling side and a bore scope will reveal the actual location of the leak. There are UA-cam videos that actually let you watch the coolant leaking into the cylinder through the head gasket. Cool shit.
All my best to Jose here in my town of residence. And a belated welcome to you kind/smart sir. Now come back in mid/late August and tell us how well you like it here.🤣 We know.🤒
I think you are correct in your assessment of why the test failed.
I've seen Scanner Danner use a gas analyzer to sniff the radiator fill hole for HCs to diagnose leaking head gaskets. However, gas analyzers that detect HCs are very expensive. The ones I saw on the internet were at least $2000. However, I've seen carbon monoxide testers that measure in a range suitable for leaking head gasket detection listed at $97. It would make for an interesting video if someone would use the scientific method to determine if a cheap $97 carbon monoxide tester can be used to diagnose leaking head gaskets. (A household smoke detector with carbon monoxide detection would definitely not work because the water vapor alone will set off the alarm.)
I forgot to mention, in order to use carbon monoxide to detect a leaking head gasket, the engine probably has to be running rich or at least at stoichiometry, which means the test would have to be done outdoors with plenty of ventilation. I don't know if a lean-running engine would produce enough carbon monoxide to be detectable at the radiator fill if the engine did have a leaking head gasket.
I think I heard you say bromophenol blue. However, a Motor Trend article by Scott Tsuneishi says bromothymol blue. I googled the 2 terms and according to the internet, those are 2 different chemicals.
Yes I misspoke. It’s bromothymol. Bromophenol is a chemical I use to stain cells at my regular job and I mixed them up lol.
Shop’s stupid economics mentality, sell used engine at 6k, 1 percent chance, sell ball joint or vc work, 80 percent chance. If they tell customer engine is bad, she’s not going to do any other work. Sometimes people have a mentality to do some work on their car to keep it “properly maintened”. Its like replacing floors when your roof is leaking.
pretty good argument there. love the analogy too lol!
Great video matt as usual, cheers from ontario ca.
I am learning horseback riding, and various other farm skills to add to my mechanical engineering background. So incidentally, I happen to be building a second skill set as we speak.
Hey that works!!! They always need ranch hands in the rural area of Colorado!
I left the industry in the late 90's due to 2 different dealer shops regularly asking me to rip people off and 'find something we can sell', I just wouldn't do it. I wonder how many good people just leave and move on. I have also experienced, asking for service as a customer and having shops simply reset the light and clear the codes up to having brake lines cut to sell brakes, unreal. These guys today are just so lazy.
I hear you man. I don't work in the industry but I am fully aware of many of the practices- I see it all the time. Thats why I like doing my own thing.
Coolant is fouling spark plug not loss of compression
Excellent video as usual. Born teacher. Truly does his sincere best. But, skip the economics/morals sermon... Just saying
We need the morality lesson more than the car repair lesson.
I watched this video earlier this morning. I appreciate a rave as much as the next guy, but yours bothered me. Every business is in business to make money. As a part time mechanic, you work on your time schedule. Techs in a repair shop work on a schedule usually laid out for them at the beginning of the day. Get it in. Get it out. And then there is the bean counter. Whether that is a hired bookkeeper, the shop owners wife, or the shop owner himself, they usually don't know what it is going to take to complete the job. They just know the bottom line has to look good.
No excuses, this was an easy diagnosis that the tech should have made. As you said, you know the shop, and the shop probably knows you. I hope that if the tech that worked on this vehicle watches your video, he doesn't take it personally, and gleans some wisdom from your diagnosis. We don't need techs getting disappointed and quitting to pursue another career.
Make no mistake, I have a high regard for you and what you do. But, you don't operate a full time shop. You pick and choose what you want to do. Shops don't have that option.
If any shop owner is watching this and reading my comment, with age comes wisdom. I am retired. I worked for a top notch sales and service company. We (and I use the word "we" because the owner made everyone feel as they were a vital part of the company) set the standard for every other company in our field to follow. I recently had this conversation with a young man I kind of mentor. Don't do low quality work for a cheap price. Do high quality work and set your price accordingly and let everyone else try to meet your standards. It won't be long before other shops will begin wondering why their customer are going to you even though you charge more.,
If there is a positive take-away from this, the tech did his job in finding other underlying problems with the vehicle. Would the customer have gone ahead with the engine repairs only to find that the vehicle needed more work done?
The customer probably trailered to within a block of a dealer and traded it in. Wouldn't be funny if it showed up at your garage to diagnose an overheating problem.😅 Sorry for the length of this. I just felt it needed to be said.
I absolutely appreciate and respect your perspective for sure and I do not disagree with it. I work in a fortune 200 corporate environment and believe me I know all about bean counters and the bottom line and hitting metrics. We do indeed have different perspectives.
I always see things from a customer's perspective even when I am doing a job for pay- and in fact even at my real job. I have even changed jobs a couple times because of this. Everything you said is true however from the customer perspective, they are not aware of the business model and in fact if they were aware of it, they would probably be less inclined to take their car to a business. When a customer has an engine issue like this, its one of the most stressful things possible because they know a huge expense is coming one way or the other. The customer is taking their car to a professional because they need a professional diagnosis on the problem to make the best financial decision possible. When a misdiagnosis like this happens, the customer is put in an even worse situation than they came in with and can lose thousands more than they already expected and it is unfair that the shop profits from it.
I in no way disagree with your description of the model- it is accurate. I am challenging the model.
"SAY HELLOO TO DA BAD GUY '' lol .. Sounds like a new Schrodinger's Box merch hat ,shirt, or sticker .
can’t live without at least a hat!!
I am a mobile mechanic but I also make and sell jewelry on the side. Also work a part time job. Definitely trying to funnel more money out of my mobile mechanic business though
I imagine the mobile mechanic business will have more potential but one thing I can tell you- ALL financially successful people I know always have multiple sources of income. Whether that’s working multiple jobs, investments, having a side business- whatever. So regardless of where you focus I’d say you are on a better track than most!!
Dealership tech here. Another issue is that the dealers don’t charge diagnostic and everyone is on flat rate. They are literally forcing us to guess. If you’re not going to pay me I’m not going to test stuff. Then the customer declines the job I don’t get paid and he goes somewhere else to get it fixed cheaper than the dealership prices, thoughts???
Yeah I am not from the industry but I totally am aware of what you are saying. I totally agree 100% with any policy where the shop charges at very minimum a flat fee for diagnostic and preferably an hourly fee with minimum of 1hr and then you and shop get paid.
Super Mario has a good video on this same issue (failed RC test). He puts pulse sensors in coolant & exhaust, amp clamp around battery, coil trigger for sync.
Thanks for sharing!
i joined ur community because i find ur videos very helpful. Especially right now that ive been struggling to get my Chevy Cobalt 2.4 running again. Right now i hit a wall and got a no start with no codes. can u point me in the right direction in ur videos to see if my coil packs r throwing spark
You will want to start with my FASTTEC video. It always finds the issue every time.
I have worked at a couple shops over the years and it doesn't suprise me that they look over the whole car. I remember the franchise would make us fill out these forms for every car that came in. I would feel sorry for the customer that just wanted an oil change and got a qoute for 1000 worth of work. Anyways, I just do this to help people out and make a little extra money now. I love watching these videos and learning about all the new tools that come out. I just bought an inspection camera from the big A for 100 and I was floored by how clear the video is and it has a side view camera. I would bet that if you pulled the spark plugs and looked in the cylinder with this camera you could see the staem cleaned piston right away. Thank you for the video!
Great comment. Yes it is hilarious to me when I see these write ups for thousands of dollars when the customer wants new tires or whatever. Sheeesh lol.
Yeah I totally which I borescoped the cylinder. Also the presence of enough coolant in the cylinder probably made it so it couldn’t be squeezed out and thus the compression didn’t lower.
I too have worked at shops that require those forms. One shop owner said, "If theres iron on the rack theres money to be made" Didn't take long to leave that one.
When I bring my vehicle to someone for diagnosis it is nice to know everything!:)))
Sometimes you can't win. If you quote roadworthy items to prevent "since you worked on my car.." they don't like it, but if you don't quote oil leaks and bald tyres, they get upset too
Why do you keep saying the compression test “lied”. The compression test simply told you the compression was equal in each cylinder. Your other tests were the answer to the engine problem.
yes I see your point. it didn’t actually lie- it told the truth indeed but I am referring to it lied because the cylinder was compromised and it failed to show it. but I agree technically it didn’t lie.
BTW, you're the greatest chemist/engineer/mechanic I've seen, hands down
much appreciated lol!
What about doing the coolant system pressure drop test. Won't tell you which cylinder but it will show the loss of coolant to somewhere? Then boroscope the cylinders to look for the coolant!
Yes but what if the cylinders are under the intake? Do you really want to remove the intake just to borescope the cylinders?? And how to determine if there is coolant in the cylinder that it isnt leaking from intake manifold?
it’s essential to show conclusively if there is a cylinder leak vs intake leak.
How about a pressure transducer in the radiator cap synced with a pulse from number one cylinder to find which one has the blown gasket?
Exactly what I will do in next video!!