CLK350 Oil Leak

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Kompressor_Dude

Active Member
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Jan 13, 2007
Messages
687
Location
Southampton
Car
CLK350 Sport
CBCC4968-F6C9-4D92-ACE6-E35A03DFA693.jpeg Hi everyone, it’s been a while since i’ve posted but hoping someone can help.

I’ve got an oil leak on the top of my engine. Thing the part is called the oil evaporator? It’s the black plastic piece bottom left of the picture. I’ve had it off and re-sealed it a number of times but can’t stop the leak. The unit was clean inside but I got a new one anyway - I can’t see any sign of oil passing between the metal and plastic when I take it off but it keeps getting through - seemingly by the bolt at the base (right-hand side in the pic). It’s filling the recesses on it’s way down the block and stinks when I slow down with the engine hot, so need to sort and clean before I do the oil change that’s due.

Is this a common problem? What sealant should I be using? Have noticed that the dipstick is often ‘popped’ slightly too - could it be because of excess oil pressure?

Any help grately appreciated!

Thanks,
 
Has anybody experienced this problem? Which sealant would be best for a plastic/metal contact to contain oil?
 
Not had this problem with mine; the engine is surprisingly clean and free from oily muck.

Any chance the oil is coming from somewhere else, and it just pools in the oil evaporator?
 
what worries me about your post is that you say the dip stick is being pushed up as well, hence one thought that comes to mind is excess crankcase pressure, which could be caused by a number of things, if it were excess oil pressure, you would be blowing oil seals.
 
Thanks for the comments guys, it’s definitely what’s leaking the oil as it’s the highest point at the top of the oil stains. Have removed and re-sealed again today so hopefully will see the problem solved.

Started the car and revved it a bit too, dipstick stayed where it was. Went for a drive and it had ‘popped’ maybe 10mm up when I got back. There is a reasonable amount of resistance to the dipstick as it seals home, so am thinking I will see if there are any other signs of crankcase pressure issues, as this could be what’s forcing oil from the seal on the evaporator too?

Car runs great and no codes so not a lot else to go on though!
 
Yes, it would make sense that crankcase pressure is forcing oil in to the evaporator; is it not supposed to scavenge oil mist?
 
is it not supposed to scavenge oil mist?
Yes, it is actually called an oil separator......
There will be a hose going from it to the induction system (upstream of any turbo) to provide Positive Crankcase Ventilation.
If you remove the oil filler cap with the engine running there should not be much in the way of pressure if things are working as they should.
If the dipstick pops up you have a problem.....
 
No turbo on the E35 M272... although I think it would be an excellent upgrade.

Sounds to me like the separator is doing what it's supposed to, but isn't coping with high crank case pressure so leaks the oil it scavenged.

(a) Check it's not due to hot coolant pressuring the block (look for the characteristic gunk on the filler cap).
(b) Check other parts in the breather system (like the PCV, which could have blocked).
(c) If nothing else is wrong, get a compression check and see if one of the cylinders is down on the others.
 
Thanks guys,

Changed the coolant recently. What came out was really clean and clear plus the temperature is always stable.

Is the PCV easy to check? Have pulled them and rattled / checked for vacuum on other cars but can’t find anything going into the crankcase? Is it worth just changing the plastic breather unit on the back of the drivers side cylinder bank? They’re cheap and it looks to have done all 125k.

I stripped the intake manifold a while ago and that was really clean inside, so I don’t think too much is passing back through this system to be recycled?

... and you’re right - a turbo would be fun!
 
The "plastic breather unit" on the back of the head is the actual oil separator centrifuge/filter thingy.....A2730100162.
That would be the next logical step.
Looks easy to get at. LH thread for the centre bolt for the filter, only 6Nn for all the bolts.

The separator on top of the head is designated "part throttle" and the one at the back of the head is "full throttle".
 
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Thanks Is this system instead of a PCV valve, or in addition to it?
 

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