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M113 Coolant mixing with oil HELP

Old Jul 30, 2025 | 02:41 PM
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2007 CLK550 Convertible
M113 Coolant mixing with oil HELP

Hey I have a 2005 C55 AMG (M113) 140k miles. I did a fresh oil change and coolant flush 3 weeks ago. And since then I’ve noticed my car has been dropping low on coolant with no external leaks. I also have a milky oil cap as well as my oil level sensor has read a .5 liter increase over the 3 week time interval. So I have reason to believe that coolant is internally mixing with my oil. After doing a bunch of research online and reading thru the cars previous maintenance history I’m pretty sure my timing cover o rings are bad and they need to be replaced. For context, oil cooler and oil cooler seals were both recently replaced 15-20k miles ago and coolant system was pressure tested with no external leaks at that time. I also believe the water pump was replaced but I’ll need to confirm. I’m pretty handy but this would be my biggest job if I do choose to take it on. I have a couple questions
1. Do you guys think it’s my timing cover o-rings or what else could it be?
2. Can this job be done with the motor inside the car and the heads still on? Hypothetically by removing front clip?
3. Does any one in NorCal area have any reputable shops or people that work on Mercedes? (Bay Area to Sacramento/anywhere near these two areas).
4. What RTV should I use? I plan on buying the fcp euro timing cover kit but it excludes RTV

I’m in college right now and if the motor has to come out, I genuinely do not want to do the job. I want to get it done as quickly and efficient as possible as I’d working in a friends garage. So I’m 50/50 on having a shop do it vs DIY, just comes down to price. Any help would be greatly appreciated. Thanks
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