Coolant reservoir boiling / bubbling
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Newbie
Joined: Dec 2021
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CLS 53 AMG
Coolant reservoir boiling / bubbling
Hi. I have encountered low coolant light warning since I took delivery of CLS 53. This problem is in another thread but i have noticed something very strange. The coolant reservoir is boiling/bubbling whenever the engine is running. I never saw this happening to any of the cars I’ve driven in the past. I would like to check if this is normal for this car because from all the information that’s available online. This is definitely not normal. Pls help. Thank a lot.
Thread Starter
Newbie
Joined: Dec 2021
Posts: 9
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CLS 53 AMG
that’s what I initially thought but I checked another CLS 53 and the coolant reservoir also show the same symptoms. I pointed this out to the service advisor at the dealer and they said this is normal. I just want to check with other 53 AMG owners that this is common and normal. Thanks.
Senior Member
Joined: Feb 2018
Posts: 333
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2019 CLS450 (C257)
that’s what I initially thought but I checked another CLS 53 and the coolant reservoir also show the same symptoms. I pointed this out to the service advisor at the dealer and they said this is normal. I just want to check with other 53 AMG owners that this is common and normal. Thanks.
I have used Xentry to bleed the coolant system before and when i turned on the aux pump for that coolant tank, I can see that it pushes the liquid through the side hose and that amount of flow creates the "bubbling" effect.
So it's perfectly normal, and its not caused by any boiling. (the coolant on this side doesn't heat up as much as the main coolant reservoir tank.
Hope this helps!
Thread Starter
Newbie
Joined: Dec 2021
Posts: 9
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CLS 53 AMG
I have the CLS450, and have the same battery coolant cooler tank. And yes it does the same when the engine is on.
I have used Xentry to bleed the coolant system before and when i turned on the aux pump for that coolant tank, I can see that it pushes the liquid through the side hose and that amount of flow creates the "bubbling" effect.
So it's perfectly normal, and its not caused by any boiling. (the coolant on this side doesn't heat up as much as the main coolant reservoir tank.
Hope this helps!
I have used Xentry to bleed the coolant system before and when i turned on the aux pump for that coolant tank, I can see that it pushes the liquid through the side hose and that amount of flow creates the "bubbling" effect.
So it's perfectly normal, and its not caused by any boiling. (the coolant on this side doesn't heat up as much as the main coolant reservoir tank.
Hope this helps!
Senior Member
Joined: Feb 2018
Posts: 333
Likes: 102
2019 CLS450 (C257)
Thank you for sharing this and it is helpful! My car is running without problems for a few weeks now since having the coolant system was bleeded. Yes, the pink coolant reservoir is still bubbling but everything is ok. I monitor the coolant temp from time to time and it says at 90 Celsius. but the engine temp is at 105 Celsius during normal cruise but rises to 113 Celsius when I drive it hard. I'm a bit worried about the high engine temp...
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