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Radiator cap leaking coolant

Old Apr 23, 2019 | 12:10 AM
  #1  
Klinh's Avatar
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Radiator cap leaking coolant

My radiator cap is leaking coolant. It getting worse. I got an appointment to bring it in Friday. The engine is running about 9 degree hotter (212F). It used to run cooler

about 204F. Has this happened to anyone?
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Old Apr 23, 2019 | 12:41 AM
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Originally Posted by Klinh
My radiator cap is leaking coolant. It getting worse. I got an appointment to bring it in Friday. The engine is running about 9 degree hotter (212F). It used to run cooler about 204F. Has this happened to anyone?
212F seems about right. I get 210F-217F on engine and ~180F on transmission.
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Old Apr 23, 2019 | 08:58 AM
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2023 C63s Coupe, 2020 CLA 45,2018 C63 Coupe,2016 C43,2014 CLA45,2013 C350 Coupe,
I had the same issue until the dealer determined that the reason for this was because the coolant level was over the full mark in the tank from the factory
after they lowered the coolant to below the level the issue has not come back (see your owners Manual, it will show the level)
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Old Apr 23, 2019 | 09:34 AM
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I have the same issue and my transmission temps have been 210-219F ever since it's been 70F.
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Old Apr 23, 2019 | 09:59 AM
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Originally Posted by Chino075
I have the same issue and my transmission temps have been 210-219F ever since it's been 70F.
Your transmission cooler does not run off the cooling circuit that uses the reservoir pictured above (the solid black one to the side of the engine bay). That cooling circuit is your main one that cools the engine. Your transmission cooler and air intake coolers both run off a different circuit that ties into the coolant reservoir directly in front of the engine (the translucent/white one).

With transmission temps that high, I wouldn't be surprised if you have a puncture in the radiator on that transmission/intake cooling circuit. Fairly common issue on our cars. You should see pink-colored coolant through the reservoir. If you don't, you have an issue.
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Old Apr 23, 2019 | 10:56 AM
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Originally Posted by msd3075
Your transmission cooler does not run off the cooling circuit that uses the reservoir pictured above (the solid black one to the side of the engine bay). That cooling circuit is your main one that cools the engine. Your transmission cooler and air intake coolers both run off a different circuit that ties into the coolant reservoir directly in front of the engine (the translucent/white one).

With transmission temps that high, I wouldn't be surprised if you have a puncture in the radiator on that transmission/intake cooling circuit. Fairly common issue on our cars. You should see pink-colored coolant through the reservoir. If you don't, you have an issue.
Thanks for the info, I will check the front one tonight and see.
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