2017 E63s Coolant leak and Trans temp overheating
I currently have a 2017 E63s which has recently started giving some problem's. I don't if both of the issues are linked, I would guess they are, but if anyone can point me in the right direction please then that would be much appreciated.
On the last few outings in the car i noticed the radiator fans would not go off, despite engine coolant temp staying normal. I was driving the car hard at the time and also noticed the Transmission temperature gauge had just gone into the red. So I stopped and turned the car off. I noticed the coolant in the big tank at the front of the engine was at normal level so wasn't sure why the fans were not going off.
A bit of further investigation and I noticed the coolant tank at the bank of the engine, under the engine cover, was empty!
Filled this up and drove home at a normal pace with no problems. A few days later and the very same thing happened after a bit of hard driving. So now I've parked the car up with no driving. The rear coolant tank was empty again and the Trans temp went into the red again.
I just wanted to know what this coolant tank feeds as there are no signs of a leakage under the car? Is it sending water to a specific radiator, Intercooler or the Turbos? And is the Trans overheating linked to this, can't see the Trans being water cooled.
Is there any tests I can run on the car to determine where the leak is?
Thanks for the help.
This is why your trans is heating when the tank is empty.
But recently I have done the following:
1. Had the coolant system pressure tested. Held pressure no problem so highly unlikely a leak is present.
2. With the above I changed the caps from both the coolant tanks just incase there was a problem with a seal. Later found to have no problems here either.
3. Checked the oil for mixture and the "milkshake of death " as suggested above. Luckily there is no mixing of oil and water.
So most things can be ruled out here, must be something else.
Trans temp went to 116°C (it goes into Red at 120°C) and 2 things were clearly observed.
1. Car seemed to lose some power and I felt some vibrations, along with some "puttt-puttt-puttt" noises coming from the back end i thought.
I slowed down as i thought the engine MIGHT have given up altogether. The car seemed to drive fine under normal circumstances but there was quite a distinct loss of power along with the noise at the back. The car was in "Sport+" mode but it might aswell have been in "Comfort" or something even less for the amount of power it was putting out.
2. I pulled in to the next gas station and checked the coolant in the little coolant tank. Low and behold it was all wet at the top and the sides. So no leaks as suspected earlier, just the coolant is coming out from the top under high pressure.
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But would the exhaust flaps cause the any kind of pressure build up in the coolant systems? Or am I over thinking this.
The noises coming from the back of the car seems to suggest a failure of the flaps, either on one side or possibly both sides. Can they be removed/deleted/cut out etc etc.
Thanks
The Best of Mercedes & AMG
Trans temp went to 116°C (it goes into Red at 120°C) and 2 things were clearly observed.
1. Car seemed to lose some power and I felt some vibrations, along with some "puttt-puttt-puttt" noises coming from the back end i thought.
I slowed down as i thought the engine MIGHT have given up altogether. The car seemed to drive fine under normal circumstances but there was quite a distinct loss of power along with the noise at the back. The car was in "Sport+" mode but it might aswell have been in "Comfort" or something even less for the amount of power it was putting out.
2. I pulled in to the next gas station and checked the coolant in the little coolant tank. Low and behold it was all wet at the top and the sides. So no leaks as suspected earlier, just the coolant is coming out from the top under high pressure.
If you left it sit for a long while, sis you notice any puddles of coolant where it sat?
I had these checked at a Mercedes specialist with a Star Machine and he did an actuation test on all 3 pumps. 2 ran fine, but the 3rd one ran for a few seconds and then stopped. Then ran for a few more seconds and then stopped altogether.
The car is going into the main Mercedes dealers tomorrow to have this pump replaced. Hopefully this will cure it and no more problem's. But if this doesn't solve it then its back to Square one.
If you left it sit for a long while, sis you notice any puddles of coolant where it sat?
Dont worry, I had the IC circuit tested, thats the one that was losing water. The pressure held fine for approximately 15 minutes, no leaks underneath or any drop in coolant level.
I'm hoping its one of the pumps on the IC circuit as has been diagnosed by a specialist. I guess I'll find out by tomorrow evening or Friday.








