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Discussion Starter #1
Hi Everyone,

I recently bought a 2004 CLK55 so im new to the forum. Although the car has full service history (89,000 miles on the clock) im working my way through servicing it myself and found an oil leak i cant seem to fix.

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The oil seems to be coming from the valve cover on the right hand side at the back of the engine as it is dripping onto the manifold but there is also oil on the steering linkage cover. The back of the engine is dry with no residue. I have changed the valve cover gasket, resealed the oil breather cover and changed all the oil breather hoses and it is still happening, at first i thought i pinched it so i took it back off to check and it was fine, I refitted and took pictures all along the side as it is difficult to see and it doesnt look like its kinked. I have torqued it to the correct torque in the WIS (with two different torque wrenches) and it is still happening. the strange thing is if I run the car it doesnt drip, i drove it 50 miles and nothing so i though i fixed it. It has now been parked for 4 days and the oil has appeared again.

During my strip down to clean the throttle body I also noticed a puddle of oil on the bellhousing under the throttle body. Does anyone know what would cause oil to leak there?

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Any help will be appreciated and im willing to check anything as although its not a major leak it is causing an oil burning smell.

Thanks
 

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Hi , Congrats on your purchase ,,,I bought mine about 1 year ago and like you set about fixing many items of maintenance,,,including leaking valve and breather covers.
Dripping oil onto the exhaust manifold can only be due to the above ,,,visually inspect your breather cover for leaking ,,and replace the valve cover gasket again..
What brand did you use ?,,,you must use genuine MB valve cover gaskets ,,they have ' Bruss' written on the tab.
Torque to 8 Nm ...over tightening will not make any difference because the valve cover has metal to metal contact with the head.
I like to use a very , very small bead of silastic gasket along the lower outside edge of the channel to prolong the life of the seal , but many people don't ....read this thread ,,

As for the oil near the throttle body ,,,I think it would be due to the same cause ,,,or could be related to the breather hose...did you clean all the small holes or ports in the breather covers ? Check that the breather hoses are all connected correctly all the way to the intake.
 

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Discussion Starter #3
Hi Benzyle,

Thanks for the reply. I am very happy with the car apart from this issue and an intermittant roof problem that has seemed to go away now.

I didnt use a genuine gasket, I used a Febi Bilstein gasket as I used their parts for a lot of things without problems. The left bank has a Febi gasket and that seems fine but I will replace the right with a genuine mercedes one and put some RTV along the seal. Should i only apply the sealant to the bottom part of the gasket or will this cause the thickness of the gasket to be different and not seal correctly?

Yes i cleaned all the holes out with a drill bit and I will double check the breather hoses are connected later.
 

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The gasket does not leak between the gasket and the head ,,it leaks between the gasket and the valve cover ,,,and mostly along the side close to the exhaust manifolds due to heat transfer causing the rubber to perish ,
so ,,only apply the rtv into the outside edge of the channel in the valve cover ....a 2mm bead only ,,,and only along the edge that will be close to the exhaust manifold ,,and also near the corners of the half moons, then push the new gasket into the channel and if any rtv comes out ,wipe it up,,, do not place any rtv on the sealing surface of the gasket.
Also , first make sure the channel is meticulously clean ,,use brake cleaner to ensure there is no trace of oil in the channel .
Then fit the valve cover to the head.
 

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Discussion Starter #5
Ok, I thought it was leaking from the sealing surface. As this is a low pressure area I didnt think it would be possible to force the oil out of the channel in the valve cover.

I have ordered a genuine gasket just to make sure and i will return the Febi one to them to see if they agree it is faulty.
 

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It is unlikely that a retailer will agree that it is faulty ,,,however ,,other brands ,,Reinz have been said to be too thin to seal properly ..I have used Febi parts and usually they are ok ,,but there is always an exception...good luck if you can get a refund ,,,
Also ,,be sure to clean the head surface as well.
 

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Discussion Starter #7
Ive started a converstion with them and they are asking the usual questions, such as did you buy the correct one and for the right side etc. I have no doubt they will try everything to get out of it.

Ill take the cover off tomorrow and make sure its squeaky clean. Hopefully it will cure it.
 

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Hi all,

I think I may have a lead. I was cleaning up the valve cover last night ready to add the RTV and noticed a rough spot. Closer inspection has reveiled what looks like a crack but is more of a groove that could let the oil out. This is in the area of the leak so hopefully adding the RTV will seal it.

Im still concerned about the oil puddle on the bell housing though as if this is the fault the oil would burn off on the manifold and not be able to get on top of the bell housing.

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Maybe ,,the crack is on the outside edge so it should not have caused a leak if the new gasket was good,,I think the main problem was the gasket was not good ,,,fitting a new genuine MB gasket should fix the leaks,,,,
Adding a little RTV as described above is really just to increase the effective lifespan by an extra few years or more ,,,
Make sure you don't go overboard with the RTV ,,,you must not have any get into the inside of the engine ,no more than a 2mm bead ,,,mostly on the outside vertical wall of the channel.
Good luck...
 

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I think that if any oil makes it out to that groove, it has already bypassed the gasket. I really believe that an OE MBZ gasket will solve the problem, and no RTV is needed. I used Victor Reinz gaskets on an M112 engine and they leaked immediately. I then bought genuine MBZ gaskets and put them side by side. The MBZ gaskets were almost twice as thick. I think that there is one company that the molds for the aftermarket gaskets and they got it wrong, so all of them are too thin.
 

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Following along as I need to replace these myself. Is your clk55 an AMG? What is cost to do it yourself with MB parts versus a dealer?

Sent from my SM-G973U using Tapatalk
 

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All CLK55's are AMG ...but doing this job on a clk500 or a clk55 is exactly the same...doing it yourself is just the cost of gaskets and rtv for the breather covers,,maybe $100 depending on which country you are in and how much the gaskets cost.
Most of the dealer cost is labour ,,because doing this job right takes a long time,,mostly cleaning the breather covers...DIY will save you hundreds of dollars...the dealers probably charge a couple of hundred more if it is an AMG ,,just because,,,

As I said above ,putting some rtv in the vc channel is optional ...it will make no difference at all for the first 10 years ....
but I believe that after that it will extend the sealing life ,possibly by years..
The choice is yours..
 

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Parf ,,re your oil at the top ,,,
Clean it up ,,,replace the gasket ,,,check the hoses ,,,
and then see if it comes back again...
 

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Discussion Starter #14
The genuine Gasket cost me £21.84 from a dealer and the Loctite RTV was £5. Luckily my leak is on the right bank which is the easiest to remove. You only have to remove the coil packs and access is fairly easily so takes 15 minutes to get it off and about 45 minutes to clean it. I did the breather cover as well and as it was my first time it was about 3 hours start to finish. The left bank has a few more brackets connected to it and you have to remove the fuel line (make sure you depressurise it first).

My dealer charges £100 + VAT an hour but will be quicker than me but im guessing at least an hour a side so a minimum of £240 labour. Its not a difficult job just time consuming and now ive had it off three times I definately recommend genuine parts. I replaced all the bolts too as didnt want the old ones snapping.

The Febi gasket was £13.55 so saved less than a tenner and now regretting it.

Appreciate all the help from everyone. Doing the job Saturday so ill keep you posted and take pictures of the Febi vs Genuine gasket. On the plus side the retailer has agreed to refund me under warranty for the Febi gasket.
 
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