Normal Operating Temperature for M156
Thread Starter
Newbie
Joined: Feb 2024
Posts: 7
Likes: 2
2011 ML63
Normal Operating Temperature for M156
HI, I have been driving 2011 ML63 for 6 years now and the temperature was always, essentially, constant 95 celsius. Never when up by 2 or down by 2. Over the past 6 months I noticed the temperature would slowly decrease so that driving in Miami in 90 degree (fahrenheit) the coolant temp would be 92 celcius for example. Turns out the thermostat was failing in the open position. I just had a new one put in and now when I drive the temp gauge is all over the place. It can now range from 85-120 celsius.
Today for example I was at a traffic light and the coolant temp hit 120 and then started to slowly decrease to 95. Another time I entered the freeway and the coolant temp dropped to 85.
The shop says this is normal for the M156, I checked the manual and that is correct. I, however, have never seen my gauge move like this while driving the car.
Can some other owners let me know your experiences, I pamper this car, its my daily driver and don't want to damage the engine obviously.
In the end I suppose I am looking for some reassurance and wonder why the gauge never acted in this manner for previous 6 years of ownership.
thanks in advance
ML63 driver
Today for example I was at a traffic light and the coolant temp hit 120 and then started to slowly decrease to 95. Another time I entered the freeway and the coolant temp dropped to 85.
The shop says this is normal for the M156, I checked the manual and that is correct. I, however, have never seen my gauge move like this while driving the car.
Can some other owners let me know your experiences, I pamper this car, its my daily driver and don't want to damage the engine obviously.
In the end I suppose I am looking for some reassurance and wonder why the gauge never acted in this manner for previous 6 years of ownership.
thanks in advance
ML63 driver
Junior Member
Joined: Jul 2018
Posts: 21
Likes: 6
From: Johns Creek, GA
2010 E63; 2017 GLC300; 2000 BMW 323i, 2020 GLS450
My 2010 sits pretty consistently at 199-200F or around 92C also. Oil temp is more variable.
Last edited by C130AMG; May 9, 2024 at 07:40 AM. Reason: Typos
Thread Starter
Newbie
Joined: Feb 2024
Posts: 7
Likes: 2
2011 ML63
The shop did not evacuate all the air out the system properly.
They used the old fashioned way of turning on the car and heat and letting the air bubbles come out. This does not work on the ML for some reason.
Once that air pockets were removed properly it works like it should and coolant temp is constant 98 now.
They used the old fashioned way of turning on the car and heat and letting the air bubbles come out. This does not work on the ML for some reason.
Once that air pockets were removed properly it works like it should and coolant temp is constant 98 now.
