W212 e63 - Coolant temperature warning light under normal driving conditions

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sixthree

Member
Joined
May 1, 2023
Messages
51
Location
London
Car
2015 E63 AMG Wagon
Hi all,

I was driving back yesterday from Cambridge to London. Outside temperature was 8 degrees and driving conditions were normal. Some highway and quite a bit of stop start in London.

About 10 mins from home (after 2 hours driving) I got an amber coolant temperature message (just the icon and no message). I quickly switched to AMG mode and saw that my oil was at 117 C (normally it is 105), and my Coolant was flashing (which was odd) between 115 and 220 and ended up nearing 123 by the time I pulled into my driveway. I checked the coolant level the following day and it is to the top of the white portion of the expansion tank.

I don't see any obvious leaks underneath the car. Would this be thermostat or waterpump related?

Anybody else experience this?

Car is a 2015 e63 wagon with 67k miles.

Thanks!

Jan
 
More likely pump or fan.....thermostat only really dictates the minimum running temp unless its jammed shut (which is very rare as they are designed to fail open and it would give you serious overheat issue within minutes)...fan dictates the maximum coolant temp.
 
Wow. Waterpump at this mileage? That's not what I was hoping for :(. Regarding the fan they were blasting on high when I parked the car. Never really heard the fans before and it was very noticeable.
 
Sorry to hear. Hopefully its just the thermostat, its the weakest part, the gel losses its effectiveness with age and if it decides to corrode, can remain partially stuck closed. If you hear the fans going crazy, then that would be them fighting to cool the water temps. If you don't see the fans working, then check the fuse and test the electric motor.

Could also be water pump, you may hear grinding noise. Definitely have it checked out, don't drive unless garage is 5 mins away. Avoid damage to engine, could blow the head gaskets or warp the heads. If it was me, I would have pulled up immediately have the car towed. Fingers crossed everything will be okay 👍
 
^^^ supposed to say wax, not gel. 🙊
 
Well I doubt it was the thremostat because when you started your drive the car got up to temp and then was ok for your trip except right near the end,so it could not be a stuck shut or even stuck slightly open,so it points to a water pump
 
Thanks mate! Yeah deff the fans were going at full speed so I don't think they are to blame. Will get her picked up and towed to the closest Merc dealer which for me is Epsom. I normally go to Guildford (for servicing stamps) and have been to PCS for any additional work.

Didn't hear a grinding noise but I'll start the car tomorrow and see what happens.

What's your take on oil temp going up to 117C?
 
Well I doubt it was the thremostat because when you started your drive the car got up to temp and then was ok for your trip except right near the end,so it could not be a stuck shut or even stuck slightly open,so it points to a water pump
That's a good point! Yeah it went up to temp fine.

I have heard that whilst the water pump is being changed you may as well also do the thermostat (because it breaks apparently?) and I've now read that people also change the turbo coolant lines? Anything else?
 
Keep us updated 👍
 
That was only for a few minutes and that was the highest it reached. Ok certainly will do!
 
Cant help to much regarding the coolant temps but you said the car isn't losing or lost coolant. Could it be a blockage in the system or as has been said the water pump on its way out. Regarding the oil temps I've have read on these AMG's hitting over 120 degrees if driven hard and V8's do run hot anyway. 117 is high if being driven moderately. My V8 this time of the year sits at about 93 anything up to 105 If in stop start slow traffic. In warmer climate when giving it a good thrashing I've seen it as hight as 123. Does cool down to about 105 when eased off the loud pedal. I have also changed the thermostat on my car a few years back. I can't remember if it was this V8 or the m113k e55 that I had the water pump replaced at about the mileage you state your car is at. I think it was the m156 I currently have that had the water pumped replaced. Could be trouble with the engine oil cooler. I had a engine oil cooler metal pipe corrode on me a few months back right behind the drivers front wheel well. It was a pig to get to a got there in the end. Was awkward pipe to replace.
 
Cant help to much regarding the coolant temps but you said the car isn't losing or lost coolant. Could it be a blockage in the system or as has been said the water pump on its way out. Regarding the oil temps I've have read on these AMG's hitting over 120 degrees if driven hard and V8's do run hot anyway. 117 is high if being driven moderately. My V8 this time of the year sits at about 93 anything up to 105 If in stop start slow traffic. In warmer climate when giving it a good thrashing I've seen it as hight as 123. Does cool down to about 105 when eased off the loud pedal. I have also changed the thermostat on my car a few years back. I can't remember if it was this V8 or the m113k e55 that I had the water pump replaced at about the mileage you state your car is at. I think it was the m156 I currently have that had the water pumped replaced. Could be trouble with the engine oil cooler. I had a engine oil cooler metal pipe corrode on me a few months back right behind the drivers front wheel well. It was a pig to get to a got there in the end. Was awkward pipe to replace.
Thanks for the advice! The car has now been picked up and will be diagnosed at Mercedes Guildford. The car up to now has been around 100-105C in this temperature during normal conditions. I'll keep you all posted about the diagnosis! I took a photo too of the waterpump pulley. Will post...
 
Hi all,

To give you an update....Mercedes Benz Guildford has been stumped. The car was delivered to them Tuesday at noon, I didn't get an update until I called them Wednesday and they weren't able to give me any diagnosis. The master tech hen spent Thursday and Friday trying to figure it out. First they said the car showed a whole host of fault codes and now they are gone. They don't seem to think there's anything wrong with the water pump visually. What are people's thoughts on my previous photo? Does the pulley look like it is 'walking away' from the belt?

I also am becoming worried now that this could have something to do with the whole cam sensor leaks with oil getting into the ECU? Would that even be a thing? Is it a temp sensor problem? But then why would my oil go up to 117c? Could both sensors be faulty?

The only thing they are able to do now is take it on an extended road test tomorrow to try and replicate it.

Really frustrating stuff....

AND I was dying to put in a set of AMG mats I got off ebay on the weekend :D - the car came with the brillo pad mercedes taxi ones....
 
If the oil temperature was very high as well as the coolant temperature, and the coolant level was normal, that would suggest no coolant circulation within the engine. I can't for the life of me see how it could be a stuck thermostat, given when the fault manifested itself, so the water pump is by far the most likely source of the problem, and I would expect that to be the first thing they will replace.
 
That's what I'm thinking too but they have now spent 3 days 'diagnosing' and haven't found a fault. I just don't get it. Seeing that the waterpump is mechanical I'm assuming there's no sensors in it right?
 
Also to anybody reading this, what is a good online source in the UK for genuine mercedes parts? I really want to buy the camshaft position sensor and the camshaft electromagnets.

Thanks!
 
Whist there may as well change the water pump then and give it a service if its due. For peace of mind I tend to stick to oem parts for engine hardware. Fingers crossed hopefully will do the trick 🙏 🙂
 

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