VLOG - W126 Mercedes 300SD - Engine Temperature Troubleshooting
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- Опубліковано 23 сер 2024
- #impalamansgarage1
This video is sort of a VLOG. I'm trying to determine why the engine
temperature consistently runs in the 95 to 100 range even in cool weather
with the heater on. The conclusion is that we'll be pulling the
instrument cluster out pretty soon. LOL.... enjoy the ramblings.
In the next video we fix this problem. The gauge is the problem.
• W126 Mercedes 300SD In...
Hey brother. Thank you for all the diesel w126 videos. I drove an '84 SD for a couple years. From time to time it would read a little hot, about where yours is reading. I would give the top of the dash by the speaker a little love tap and it would also jump back down to under just barely under the middle of the gauge. Sometimes my fuel gauge would jump a bit too with it. I learned very recently that this is a semi-common issue and it is in the cluster. I'm 99% sure a new/used OP/temp/fuel cluster was the remedy. I found this info in a forum somewhere. Either Benzworld or peachparts. If i can find it again I'll send it over. Please keep cranking out 126 videos.
Thanks! Going to pull the cluster soon I think and see what can be done.
I had the exact same problem with my W140 S320, and ended up replacing the ENTIRE cooling system w/ Genuine MB parts, only to get the same high temp reading all the time. Replacing the temp gauge sender cured it.
Ultimately for me it was cleaning the corroded connections in the temp guage that cured this issue. Later video.
I have the exact same issue. I used a infrared thermometer on the block, hoses, and radiator and it read 75-80c every where. The gauge head is messing with you and me, don’t worry about it.
I fixed the problem. The gauge was at fault. It was a grounding problem. Refer to my video titled "W126 Mercedes 300SD Instrument Cluster Issues - Temperature Gauge FIXED ! - Part 2"
Pull condom on the neck of the expansion tank, so you understand whether the gases go into the cooling system. Typically, the temperature on a 617 motor rises due to bursting gases.
No. Temp gauge in the car is faulty. There is nothing wrong with the engine cooling system.
That’s where mine is running just under the 100 mark with the ac on during the summer on a 99 degree ambient temperature day
Have you replace the fan clutch, they don't last long.
Ultimately this temperature problem was simply bad a connection in the temperature gauge in the dash. Bad grounds. This is a very common problem with the W126 cars. There is another video on it here: ua-cam.com/video/FGEK6XfbGz0/v-deo.html
Am in Florida de car temp stays at 80 without A/C on. During 35 -90 mph, now when am in NYC with the car am batting between 80 to90 still without A/C on nor heater. And yes my gauge needle jumps too worrying me! Am in 88 420SEL with only one fan, never seen aux fan kick in, have to test it. I know it as been 2 yrs that you posted this video, what was the outcome? Thanks for your great videos!
The problem ultimately turned out to be a faulty temperature gauge in the instrument cluster. The electrical grounds between the temp gauge and the circuit board will corrode causing false readings and fluctuations. Let me go find that video link. I will paste it here.
The solution for this issue is cleaning the grounds in the instrument cluster. Here is the video. ua-cam.com/video/FGEK6XfbGz0/v-deo.html
i think the gauge temperature sensor is in the thermostat housing, the one you changed is for the glow plugs
No sir. With the engine running, if you pull the wire off of the sensor on the side of the block the temp guage in the car immediately drops to zero. It is clearly the engine coolant temp sensor.
@@ImpalamansGarage hmm i thought wrong
random & late, but I read the temp sensor on the thermostat housing is related to the blower motor when the temp is below a certain point to avoid blowing cool air into the cabin on accident....
Its your gauges on the left side. I would upgrade to a gen 2 gauge set, looks nicer and are far less likely to have electrical problems
I'm good with this plan. lol
I just did top overall and change the fan. My gauge is about 120 c .
It's your temp gauge. They are bad about corroded grounds. The fix is in this viseo. ua-cam.com/video/FGEK6XfbGz0/v-deo.html
Each gauge has a threaded shaft and a nut holding it onto the circuit board in the gauge cluster. There is a contact pad around the mounting pad on the circuit board. This pad gets corroded and leads to poor grounding. If you take the gauge cluster apart and clean all contacts and ground points the gauge will read properly. It's actually not a hard job.
Thank you , I tried sanding temp gauge but no success. I will try changing temp sensor . Hope it works
Assuming you replaced the thermostat and coolant reservior cap? Water pump too? Any one of these things can lead to higher temps. Recommend a laser temp gauge pointed at the radiator and thermostat housing to get a feel for whether or not the temp reading you are getting is accurate. Also just a hand quickly placed on the upper radiator hose can tell you a lot. Compare it to another car that is operating normally. You can generally tell when an engine is too hot just by grabbing the upper radiator hose.
@@ketam Not sure what all you have done to the car but sometimes a radiator can get clogged preventing proper coolant flow. Maybe have it cleaned at a radiator shop if you suspect this.
The white bar that’s under the 120 white bar, NOT the 120 marker.
The bar between 80 and 120 is around the 212 F mark. The engine is not running that hot. The gauge is lying to you. LOL..... I found out in a later video that corroded grounds inside the gauge will cause these gauges to read a little high when in fact the engine is running fine. Check this out. Let me know if you have questions. ua-cam.com/video/FGEK6XfbGz0/v-deo.html
It is wrong coolant, check the Mercedes recommendation.
Check the Mercedes recommendation from 1984?
Mine does the same thing
Mine runs near the mark under the 120 on the hottest day with the air conditioning on
You should not go over 90 C,....Replace the fan clutch.They don't last long.
As far as I know the marker inbetween 80C and 120C is not 100C, but 90C at Mercedes.
Disagree. The mark is half way between 80 and 120 so why would it not be 100 ? The consensus in every learned discussion I've had is that the middle mark is 100.
@@ImpalamansGarage Because it is more worth to indicate 90degC functionally as remarkable limit. In the middle between 80 and 100? It is only matter of calibration. It is better if you clarify this with an MB workshop.
An old diesel engine (like 300SD) does not like 100C (remember, radiator cap is for 100C if there is no expansion tank, and 120C with expansion tank), but on highway 90C is OK for cooling water.
Another indirect arguement: MB manual says that you may open the radiator cap if the water temperature is below 90C (194F) to avoid hot water blasting out.
As per your arguement the 90C is not even indicated, only 100C. How could Customer know where 90C is then? MB does not take the risk that Customer opens the cap wrongly.
Here is the video where I repaired the temperature gauge and fixed the high reading problem. ua-cam.com/video/FGEK6XfbGz0/v-deo.html
@@zoltantakacs866 I assume you are referring to section 20-010 of the service manual. I have the complete two volume service manual. On page 20.8-010/2, Step 1 under "Draining Tank" it does say that you can remove the expansion tank cap below 90c. If you are making an assumption that the middle mark between 80 and 120 is in fact 90 simply to provide a visual mark to know if it is safe to remove the cap, that is a bit of a stretch in my opinion.
My car always runs at 40C.
I'm starting to think maybe my sensor is off?
Maybe. Will be interesting to know what you find. I'd look at the sensor first since it's the easiest to get at. Simply disconnect the sensor wire at the engine and see what happens. Might lead you somewhere. Also they are cheap enough to just replace it and see what happens. Might get lucky. A poor ground inside the gauge in the car would cause a high reading in my experience. Look at my later video on that. If you've never gone through the thermostat housing, this may be a good time. Mine was nasty.
Thermostat. Replace it. They wear out over time and get slow.
@@Johnathan_Waters Yeah it was the Thermostat. Not the Sensor. Was easy to replace. The old one was an original Mercedes one thermostat.
turns out my sensor was bad. Car was still sitting at 40C with new thermostat.
I think you have a bad gauge
Yes I repaired it in this video. Grounding problem. ua-cam.com/video/FGEK6XfbGz0/v-deo.html
These cars should not run at that middle mark. (About 212) This problem is so common that a lot of folks think these cars actually run that hot. I've seen it a lot on forums. The gauges corrode on the inside. The ground connections become bad and cause erroneous high temp readings.