Leaking Oil Cooler
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Leaking Oil Cooler
Just thought I'd let yall know. You may want to check around the lower part of the oil cooler to see if any oil is there. It's part of the oil filter housing. It drips onto the belt and pulleys and makes a mess. Mine is pretty steady.
There are two small ring gaskets oval and round. About the size of a quarter each and cost $25.00 each!!!LOL.
If small the leak could go unoticed for a while so I thought I would let all know in case its a C43 common issue. Use an extendable small auto mirror and you can see around pretty good. Look on the bottom of it obviously.
I'll post pictures when it's apart if anyone needs a DIY.
There are two small ring gaskets oval and round. About the size of a quarter each and cost $25.00 each!!!LOL.
If small the leak could go unoticed for a while so I thought I would let all know in case its a C43 common issue. Use an extendable small auto mirror and you can see around pretty good. Look on the bottom of it obviously.
I'll post pictures when it's apart if anyone needs a DIY.
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From: North Carolina
98 Black C43 , 12’ ML 350 Blutec
Just thought I'd let yall know. You may want to check around the lower part of the oil cooler to see if any oil is there. It's part of the oil filter housing. It drips onto the belt and pulleys and makes a mess. Mine is pretty steady.
There are two small ring gaskets oval and round. About the size of a quarter each and cost $25.00 each!!!LOL.
If small the leak could go unoticed for a while so I thought I would let all know in case its a C43 common issue. Use an extendable small auto mirror and you can see around pretty good. Look on the bottom of it obviously.
I'll post pictures when it's apart if anyone needs a DIY.
There are two small ring gaskets oval and round. About the size of a quarter each and cost $25.00 each!!!LOL.
If small the leak could go unoticed for a while so I thought I would let all know in case its a C43 common issue. Use an extendable small auto mirror and you can see around pretty good. Look on the bottom of it obviously.
I'll post pictures when it's apart if anyone needs a DIY.
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From: Portsmouth, NH
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Here are the pics of the oil cooler repair. I didn't enjoy the process. It was kinda tricky working around the tight areas as any C43 owner would know
First thing was to drain the coolant and remove the yellow arrow stuff including the coolant hoses (1)large to radiator (2) feeding bottom inlets of the oil cooler held on by crimp style hose clamps. You need long reach needle nose to get to these. There are also four corner located torx bolts holding it on.
Here you can see the lower coolant lines contected to the oil cooler. I pluged the lines up so nothing could fall in there as I'm sure it would have.
Here the coolant lines are in blue with a dashed line showing the larger one removed. The red arrows are the older gaskets which appeared to the human eye to be fine once I removed them.
Things all cleaned up. The new gaskets cost $38!! for that much little rubber. They are a tiny mm thicker than flush. They flatten out and form a seal once the cooler is tighted down. Heres the kicker!! The tiny leak was still there once I finished!!! I'm thinking that the cooler itself or the filter case is no longer straight by a hairline. I repeated the process and added a tiny bead of high temp gasket seal around the outer edge of the gaskets to form an additional seal. Use the outer edge as to prevent any sealant from getting into the oil. I think that a flat gasket the shape of the cooler face would be a better design like a head gasket material. It would be a small sheet.Two holes cut out for the oil flow.
All done. No hint of leak after a week or so of driving...knock on wood.
First thing was to drain the coolant and remove the yellow arrow stuff including the coolant hoses (1)large to radiator (2) feeding bottom inlets of the oil cooler held on by crimp style hose clamps. You need long reach needle nose to get to these. There are also four corner located torx bolts holding it on.
Here you can see the lower coolant lines contected to the oil cooler. I pluged the lines up so nothing could fall in there as I'm sure it would have.
Here the coolant lines are in blue with a dashed line showing the larger one removed. The red arrows are the older gaskets which appeared to the human eye to be fine once I removed them.
Things all cleaned up. The new gaskets cost $38!! for that much little rubber. They are a tiny mm thicker than flush. They flatten out and form a seal once the cooler is tighted down. Heres the kicker!! The tiny leak was still there once I finished!!! I'm thinking that the cooler itself or the filter case is no longer straight by a hairline. I repeated the process and added a tiny bead of high temp gasket seal around the outer edge of the gaskets to form an additional seal. Use the outer edge as to prevent any sealant from getting into the oil. I think that a flat gasket the shape of the cooler face would be a better design like a head gasket material. It would be a small sheet.Two holes cut out for the oil flow.
All done. No hint of leak after a week or so of driving...knock on wood.
Last edited by NitrogenBalance; Oct 15, 2006 at 10:22 AM.
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From: bay area
98 C43 AMG, 93 190E 2.6
nice pics, and good post. hope my oil cooler doesn't develop a leak, it looks like a ***** to getin there. good luck with the fix, let us know if the extra gasket sealant did the trick.
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From: North Carolina
98 Black C43 , 12’ ML 350 Blutec
Great write-up and fantastic pics! Stupid question but I have to ask - Did you try torqueing everything to spec BEFORE you took on the task of replacing the gaskets.I just wonder that MAYBE, over the course of 8 years , they had loosened up? 
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I hope to tackle the wheel bearing(if thats the prob) this wednesday.
Anyone know of any odd size tools or things needed for the bearing replacement.......
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From: California
Obsidian Black C43, Silver C43, Silver Carlsson E-class wagon, Brabus G-class
Nice post. I have exactly the same problem, which I thought the leak was coming again from the front crank cover. I've had this leak for a while and let it go. Last night, the drive belt broke, which I just replaced 20,000 miles ago. It's probably due to oil constantly leaking on the belt.
This happened right after seeing another C43 at Claim Jumper in Valencia, CA and chatting a little bit with the owner.
A supposedly early weekend turned into a very late repair in the parking lot. I also realized that the spare belt I had was the stock belt. I actually needed something that was 1 inch longer since I have the EVO sport pulleys.
Anyhow, back on the road and the next repair is definitely the oil cooler leak.
Thanks again for the post. This will be my next weekend project.
This happened right after seeing another C43 at Claim Jumper in Valencia, CA and chatting a little bit with the owner.
A supposedly early weekend turned into a very late repair in the parking lot. I also realized that the spare belt I had was the stock belt. I actually needed something that was 1 inch longer since I have the EVO sport pulleys.
Anyhow, back on the road and the next repair is definitely the oil cooler leak.
Thanks again for the post. This will be my next weekend project.
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Buy some high temp RVT sealant as well. Put a very small bead around the rubber gaskets outside edge before reasembling. Also, a hairline bead in the channel that the rubber gaskets sit. Not to much and none on the inside gasket edges as you don't want sealant being picked up in the hot oil stream. My tech recomended this because he told me that the surfaces may not be 100% flat over time and the OEM gaskets won't spread or flatten enough to make a seal. Tighten the bolts down in a pattern like you would a wheel.
Lastly, I should have removed my fan for easier access. It would have saved an hour from dropping and trying to reach things.
Lastly, I should have removed my fan for easier access. It would have saved an hour from dropping and trying to reach things.
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c43
I had this same problem last month. I posted here somewhere as to how to fix this without going through all........... you need to tighten the left and right BOTTOM bolts on the cooler real tight. they will not break or strip, just dont use a HUGE wrench. I used the small 1/4 drive. the problem is the screws do get loose (or mb loosens them when our cars are serviced,just a theory) and oil leaks. specially the screw near the block, that one really needs to be re-tighten. after the work which took less than 1 minute the leak is gone. i been driving it hars too just to make sure.
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From: Aliso Viejo, CA
2005 SL 500
Check out the post "C43 leaking oil.. likely spot?" and look at the photo I posted toward the end of the thread....
Is that 2 bolt plate the engine timing cover? That's what's leaking on mine not the oil cooler, I just want to make sure I order the right seal, thanks.
Is that 2 bolt plate the engine timing cover? That's what's leaking on mine not the oil cooler, I just want to make sure I order the right seal, thanks.
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From: City with Tall buildings!
C43/55,2k11 Volvo S60 T6AWD,2k Audi B5 S4,95 Eagle Talon Tsi AWD 500+awhp
Excellent post Nitro,guess I will tackle this problem before I actually install this stupid idler pulley.
I believe that this is why my serpentine belt got damaged which also ruined my idler pulley in the process. Belt had at least 20 k miles which was chgd brand new when I had the 5.4L motor dropped in.
I believe that this is why my serpentine belt got damaged which also ruined my idler pulley in the process. Belt had at least 20 k miles which was chgd brand new when I had the 5.4L motor dropped in.
MBWorld Fanatic!
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From: City with Tall buildings!
C43/55,2k11 Volvo S60 T6AWD,2k Audi B5 S4,95 Eagle Talon Tsi AWD 500+awhp
I had this same problem last month. I posted here somewhere as to how to fix this without going through all........... you need to tighten the left and right BOTTOM bolts on the cooler real tight. they will not break or strip, just dont use a HUGE wrench. I used the small 1/4 drive. the problem is the screws do get loose (or mb loosens them when our cars are serviced,just a theory) and oil leaks. specially the screw near the block, that one really needs to be re-tighten. after the work which took less than 1 minute the leak is gone. i been driving it hars too just to make sure.
MBWorld Fanatic!
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From: City with Tall buildings!
C43/55,2k11 Volvo S60 T6AWD,2k Audi B5 S4,95 Eagle Talon Tsi AWD 500+awhp
After takingt this cooler off the engine I am definitely going to replace both gaskets. I removed everything,fan,radiator,it just makes the job that much more easier for you to spray and clean ALL the gunk off the motor ,especially in hidden places like behind the steering pump pulley and areas like that.
Well I know one dealer has two of the three gaskets I need,hopefully I can have my car back on the road by this Mon., the latest.
Well I know one dealer has two of the three gaskets I need,hopefully I can have my car back on the road by this Mon., the latest.
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05 c55 silver, 98 Imperial Red C43
Nice thanks a lot man
Noticed a small leak under my car and was looking into that area in my engine bay today. Thats exactly what I thought it was
Thanks for the write up
Noticed a small leak under my car and was looking into that area in my engine bay today. Thats exactly what I thought it was
Thanks for the write up
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From: City with Tall buildings!
C43/55,2k11 Volvo S60 T6AWD,2k Audi B5 S4,95 Eagle Talon Tsi AWD 500+awhp
Dude! I was shocked!
Damn gaskets cost me like 30.00 a piece. 63.00 total.!
I can't believe it. They look like regular rubber gaskets to me. Or something I could have made with the factory black rtv sealant used to seal the oil pan to the block.
Talk about robbery!
Jeez!
Well at least I also got to see a SL65 Black Series on the show room floor. Incredible. sticker price: 300k
Damn gaskets cost me like 30.00 a piece. 63.00 total.!
I can't believe it. They look like regular rubber gaskets to me. Or something I could have made with the factory black rtv sealant used to seal the oil pan to the block.Talk about robbery!
Jeez!Well at least I also got to see a SL65 Black Series on the show room floor. Incredible. sticker price: 300k
Last edited by ProjectC55; Dec 26, 2009 at 04:44 PM.
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From: New York
Mercedes S55 AMG
These oil cooler leaks are common, I have an S55 AMG and had the same problem - it's good to get fixed because it can leak onto the belt and cause it to slip out or snap if it gets too saturated.
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From: City with Tall buildings!
C43/55,2k11 Volvo S60 T6AWD,2k Audi B5 S4,95 Eagle Talon Tsi AWD 500+awhp
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when you removed the hoses I noticed you have removed the oilfilter, was that b/coz you were going to make an oilchange?
or was that just for easier axess when putting the new gaskets in place on the oilcooler sidewall?
Did you have to drain the engine from oil before you began removing all hoses, to prevent oil pressure leaks where those bad gaskets are placed?
Did you also change the front squared timing case gasket?
these gaskets come in 2 different versions,
old style is only a square rectangular shaped gasket,
and the revised gasket is squared rectangular with a centre piece rubber which is better.
Early C43's had the first inferior gasket, and later had the revised.
How can the engine serial number be checked knowing which gasket is on the engine?
Autohausaz lists each gasket up to a certain engine serial number.
or was that just for easier axess when putting the new gaskets in place on the oilcooler sidewall?
Did you have to drain the engine from oil before you began removing all hoses, to prevent oil pressure leaks where those bad gaskets are placed?
Did you also change the front squared timing case gasket?
these gaskets come in 2 different versions,
old style is only a square rectangular shaped gasket,
and the revised gasket is squared rectangular with a centre piece rubber which is better.
Early C43's had the first inferior gasket, and later had the revised.
How can the engine serial number be checked knowing which gasket is on the engine?
Autohausaz lists each gasket up to a certain engine serial number.
