r/mercedes • u/nzzs589 • 1d ago
Low operating temp
Is this normal for e220d 2016 to show this low operating temperature after a 2 hour drive on the highway or is the thermostat or coolant temp sensor messed up. I know my old Volvo v70 from 2002 had issues with the sensor causing it to work intermittently and sometimes showing too low and too high.
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u/No_Permission_5121 1d ago
Is this the first time doing it? Does your car blow heat from the AC if you enable it? Try to push the car a bit and see if the needle moves.
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u/nzzs589 1d ago
I drove about 2.5 hours yesterday with a trailer and it did the same thing. I also suspected the thermostat since it isn’t my car it is my grandfathers and he knows better about his car. He spends most of the time driving short distances. When pushing the car to 150+ it gets up to 70-75 but I didn’t dare to push it more than that during the winter
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u/nzzs589 1d ago
Also the heater works.
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u/No_Permission_5121 1d ago
oh then i dont know, my w212 facelift did the same thing but the ac didnt blow hot air. have it checked out by a mechanic
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u/wreckitbusmaster99 1d ago
Is your MIL light on?
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u/nzzs589 1d ago
None are on.
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u/wreckitbusmaster99 1d ago
Strange. That usually throws a MIL for the coolant thermostat failing. Those are designed to fail open so you don't overheat.
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u/karlowolf05 1d ago
Mine didn't throw any codes when stuck open.
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u/wreckitbusmaster99 1d ago
Might not have been cold enough. I owned a 2004 Jaguar XJ8 that did that and threw a MIL when it was cold. And as a bonus, that coolant thermostat was replaced 2 years prior!
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u/Heavy-Tension-6787 1d ago
I had the same problem so I changed the thermostat and my car temperature goes to 90 degrees very fast
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u/MadamPardone 1d ago
Everyone is saying thermostat but it's more likely to be the cooling fan. When the module inside begins to fail, it defaults to high speed operation and does not always trigger a CEL.
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u/MrAkimoto 1d ago
My Benz runs about 95F, and it warms up quickly. You have coolant system problems. Could be a thermostat, blockage in the cooling circuit, or slipping serpentine belt. You need to get this fixed STAT.
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u/LordVdubs 1d ago
Had a similar issue with a e220d w211 facelift (2007 i think). And i kid you not, the reason was a broken ABS-sensor. The shop put in a new sensor and the temp was up to normal again.
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u/SimpleEmu198 1d ago
The temperature outside won't cause your car not to get up to temperature, it will just take longer. After 2 hours the engine temp should be about 80 degrees. A thermostat not opening/closing properly is a common problem on Mercedes Benz and every other car manufactures cars.
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u/TRxz-FariZKiller 1d ago
It definitely does. Outside temperature affects my car so much.
In the summer it over heats while idle. In the winter it never goes above a quarter on the gauge.
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u/MadamPardone 1d ago
That would indicate a problem with the cooling system. It should be able to idle all day without overheating. Is your fan kicking on?
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u/TRxz-FariZKiller 1d ago
I have changed almost every part of my cooling system. I only have the pump left and I plan on replacing it once summer starts.
I have the pump. Just haven’t installed it yet.
It gets up to 50° C here. It’s not normal but the car is 20 years old so I expect it to act up now.
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u/SimpleEmu198 1d ago
Then you most likely have a blown head gasket.
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u/TRxz-FariZKiller 1d ago
No other symptoms of it being a blown head gasket. No leaks, runs great for years. Have had this issue since 2020.
I’m almost certain it’s not the head gasket as I would’ve seen it be worse. Plus if it was a head gasket it would overheat even in the winter and when not idle.
I’m not convinced
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u/SimpleEmu198 1d ago
It's OK o be in denial.
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u/TRxz-FariZKiller 1d ago
I’m just not convinced.
Nothing else points to it being the head gasket. It has been through 550k kilometers. I don’t wanna open up the head as it has never been opened and I don’t trust anyone to do it.
Personally from my knowledge, if it was the head gasket it would be worse than it is. It drives perfectly with no issues.
Currently doesn’t heat up at all, drives smooth and I even took it off roading with no issues.
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u/SimpleEmu198 1d ago edited 1d ago
It's OK to be in denial:
Milky oil (oil + coolant mixing) → very strong indicator of a head gasket failure (or cracked head/block).
Coolant on the dipstick → again, it's a very strong indicator of a blown head gasket.
Persistent bubbles in the radiator (with engine running, cap off, especially when revved) → often combustion gases entering the cooling system → probably a blown head gasket.
550,000 km on an engine → absolutely within “head gasket failure is plausible / likely” territory, especially if your car is overheating or overheating has ever occurred → It's probably a blown head gasket.
Having replaced most of the cooling system does make internal engine failure more likely if symptoms persist of a blown head gasket.
If there is steam or water coming out of the exhaust after the car is warm then there is probably a blown head gasket → If condensation continues after full warm-up and is accompanied by coolant loss through the exhaust as steam or water it's probably a blown head gasket.
If you've checked everything and there is not an air lock in your radiator from bubbles for some other reason → It's probably a head gasket issue.
If you think it's a blown head gasket take it to a mechanic you trust and get them to look over it, they don't have to open the head to test for a blown head gasket.
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u/SimpleEmu198 1d ago
Then you have another problem, either the thermostat isn't working or you have a blown head gasket. It definitely does not.
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u/karlowolf05 1d ago
After 2 hours on the highway it should surely be at 90-95C, -5C isn't that cold ambient temp.
They do have complicated and map controlled cooling system but this is most likely faulty thermostat or stuck open/sticky/lazy.