Cause for cracked turbocharger coolant expansion tank?
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 21
Likes: 6
From: USA
2003 C32 AMG Sedan
Cause for cracked turbocharger coolant expansion tank?
Doing an oil change on the '17 E400 (30k miles) and noticed the coolant expansion tank that bolts directly to the engine has a big crack going all the way around the top. There was no residue or staining on adjacent parts, which indicates that it probably hasn't been spilling coolant out (surprisingly), but of course I tracked down the part, which turned out to be a turbocharger coolant system expansion tank, and it's on its way.
My question is, what causes this? The car is pretty low mileage, and I don't drive it hard. Is there anything I can do with the new one to prevent this from happening again? I'll try to post pics of the tank I'm referring to, with its damage visible. Thanks everyone!!
My question is, what causes this? The car is pretty low mileage, and I don't drive it hard. Is there anything I can do with the new one to prevent this from happening again? I'll try to post pics of the tank I'm referring to, with its damage visible. Thanks everyone!!
Out Of Control!!
Joined: Apr 2019
Posts: 11,981
Likes: 6,819
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
this has to do with heat and pressure.
These engine can readily develop high heat issues.
The aux coolant tank is connected to intake heat exchanger that should be checked for leaks
These engine can readily develop high heat issues.
The aux coolant tank is connected to intake heat exchanger that should be checked for leaks
Super Member
Joined: Aug 2004
Posts: 954
Likes: 245
E550 Coupe 2wd (2016)
My turbo tank is fine, but the engine tank not so much. It cracked and leaked a couple years ago, but doesn't leak now so I didn't replace it. The heat is what gets 'em. Hot as F under there.
Thread Starter
Junior Member
Joined: Mar 2023
Posts: 21
Likes: 6
From: USA
2003 C32 AMG Sedan
Thanks for the input folks! When researching leaky charge air coolers for the M276, you pop up in several of the more relevant threads, CaliBenzDriver. Ty for spreading this important info. Away at uni now but hoping to do the replacement myself (of aux cooling tank, not intake air cooler) when I visit my family again (it's their car). Anything exceptionally tricky?
Last edited by MaxC32; Jun 17, 2025 at 11:32 AM.
Out Of Control!!
Joined: Apr 2019
Posts: 11,981
Likes: 6,819
From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
UP TO LIMITS
Doing an oil change on the '17 E400 (30k miles) and noticed the coolant expansion tank that bolts directly to the engine has a big crack going all the way around the top. There was no residue or staining on adjacent parts, which indicates that it probably hasn't been spilling coolant out (surprisingly), but of course I tracked down the part, which turned out to be a turbocharger coolant system expansion tank, and it's on its way.
My question is, what causes this? The car is pretty low mileage, and I don't drive it hard. Is there anything I can do with the new one to prevent this from happening again? I'll try to post pics of the tank I'm referring to, with its damage visible. Thanks everyone!!
My question is, what causes this? The car is pretty low mileage, and I don't drive it hard. Is there anything I can do with the new one to prevent this from happening again? I'll try to post pics of the tank I'm referring to, with its damage visible. Thanks everyone!!
The AUX cooling circuit cools the air after turbos charge. It heats up out of control.
When the car idles too long it overheats the intake air by sucking already hot 200°F air instead of normal ambient (50 to 100°F).
The hot turbo impellers further heat up the air that travels through charge cooler.
That charge heat exchanger is frequently found heat-damaged with leaks.
This system works well until pushed to it's extremes. Prevent these conditions.
Last edited by CaliBenzDriver; Jun 17, 2025 at 03:11 PM.
