M113 Coolant mixing with oil HELP
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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
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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Joined: Jun 2018
Posts: 249
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From: San Antonio, TX
2005 C55 AMG
That would be where I would look first (and pray that wasn't it). Try the head gasket test kits that test for hydrocarbons in the coolant while the engine is running (blue fluid that you hope doesn't turn yellow). It's DEFINITELY getting in there, but if you don't have to pull the heads, it's much cheaper to fix. Also, if it tests positive, STOP DRIVING THE CAR! Pulling the heads is a big expensive job, but trust me, it's still cheaper than replacing the engine - maybe $2500-5000 versus the $9000 I spent replacing my engine (for other reasons). DIY of course will be much cheaper.
Hydrolock is catastrophic.
Hydrolock is catastrophic.
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Joined: Sep 2007
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05 c55 silver, 98 Imperial Red C43
Engine has to come out.
In order to take the timng cover off, the oil pans have to come off.
Oil cap will look milky from condensation so its not neccessarily the coolant mixing. Have your oil tested first.
I had a very slow cooland leak forever and finally figured it was the return line that comes back into the coolant reservoir. There was no visible leak, coolant was just evaporating over time and dropping.
Have the system pressure tested first.
In order to take the timng cover off, the oil pans have to come off.
Oil cap will look milky from condensation so its not neccessarily the coolant mixing. Have your oil tested first.
I had a very slow cooland leak forever and finally figured it was the return line that comes back into the coolant reservoir. There was no visible leak, coolant was just evaporating over time and dropping.
Have the system pressure tested first.
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Joined: Sep 2007
Posts: 1,481
Likes: 310
95 SL600
head gasket failure is quite rare on the 112 and 113 engines, but the front cover orings are common, oil on one side, and coolant on the other leads to swelling and turning into jelly. It’s a real pain in the *** job and really a very bad design, that if done correctly also requires head removal, new head bolts, new cam retainer bolts, head gaskets and more. Figure $600 or more in parts alone and it would be silly not to pull the engine at that point.
You can attempt to do it in the car with the heads on, but the subframe will need to come out, and with help from a divine force, you won’t damage the head gasket either removing or installing the cover. While I have done covers with heads on, it requires luck to make sure the orings stay in place, because the cover is installed before the heads go on from the factory. The front part of the cover is sealed with RTV and sliding it into place with the heads on and the sealant usually ends up with one of the multi layered steel head gasket layers crinkling up. It’s a really unnecessary engineering issue.
These engines really weren’t meant to be rebuilt, as they cannot be bored or honed economically, so the engineers game was to put it together once, and throw it away when it came time to rebuild, and it is very evident when it comes time to work internally on them.
You can attempt to do it in the car with the heads on, but the subframe will need to come out, and with help from a divine force, you won’t damage the head gasket either removing or installing the cover. While I have done covers with heads on, it requires luck to make sure the orings stay in place, because the cover is installed before the heads go on from the factory. The front part of the cover is sealed with RTV and sliding it into place with the heads on and the sealant usually ends up with one of the multi layered steel head gasket layers crinkling up. It’s a really unnecessary engineering issue.
These engines really weren’t meant to be rebuilt, as they cannot be bored or honed economically, so the engineers game was to put it together once, and throw it away when it came time to rebuild, and it is very evident when it comes time to work internally on them.
