dweb4

I’m having hard time finding oil leak. I’ve checked the normal spots Crankcase Breather have a little oil on one bolt. But I have a couple drops leaking on the drivers side and I don’t have any oil leaking from rear cam plugs. I’ve attached a couple pics of bottom of engine with cover off. This is picture on drivers side where the differential is. Unsure if oil pan is leaking or if there is another seal/plug I’m missing. It doesn’t smell and oil level is normal. Any suggestions would be appreciated.

artim808

What engine you have?

dweb4

Unsure of the engine number but it’s a 2011 non turbo V8 also I have a 4matic.

artim808

Did you checked really all rear plugs? There is one bigger and 2 smaller. Check video below:

dweb4

Yes I checked them. I found a little bit oil leaking from one of the pcv bolts. The cam plugs are clean. Would that one bolt cause oil to leak to the bottom over to the drivers side?

artim808

It depends for how long is leaking. Also check around oil cooler it can be leaking from there as well.

dlafever

+1 on the oil cooler. I found one of my spark plug wells was full of oil a few years back. Following the WIS procedure to wash the engine allowed me to see that the oil cooler was leaking and it was blowing back to the first spark plug.

JDowney

Hi,

Ensure that there is no Oil Leak from the oil cooler gasket. It is a $50 gasket, but it costs thousands to install... My 2012 has the dreaded oil leak
(just happened a few months ago), and so did my 2013 but that was fixed under warranty.

Jeff

dweb4

I found leaks it’s coming from oil cooler, oil filter housing assembly and the PCV valve. Heading to grab seals and parts. I have standard V8 non turbo 4 matic. Attached a pic of motor.
I know upper radiator hose bracket, belt, idle pulley, drain radiator and remove housing assembly. I know I’m missing more so please fill me in. I’m pretty mechanically sound. Just wanted to know some tips to make it easier. Thanks.

Kebowers47

Mercedes alloy V-8 and V-12 engines ALL will leak oil because Mercedes has some 'multi-surface. multi-part ' joints to seal and IMHO they used the incorrect elastomer seal material. The "green" seals are made of HNBR (hydrogenated nitrile butyl rubber) which is typically used in automotive A/C refrigerant seals. It IS a 'stable' and 'good' seal material for many conditions-just not these multi-direction expansion joints. It loses its attachment to the SURFACES of the joints and allows engine oil to seep through. When one has three or more independent surfaces in aluminum allow casting assemblies, they want to expand in different directions when heated and cooled. Not only do they have different rates of temperature change and thicknesses (stiffness,) the three or more directions of expansion and shrinking guarantees differential movement at the sealing surfaces. IF the sealing gasket cannot withstand continual strain and flexing and maintain the contact pressure, the gasket will shred or come unstuck,allowing oil to creep past the sealing surface. Engine oil has very high 'oiliness' because of additives to improve the oil wetting of surfaces. It WILL creep through most any joint not having a perfect seal (like a canning jar seal). Mercedes has used 'slicone' type curing sealing compound in some of the joints attempting to 'fix' the problem, which has cost them $MILLIONS in warranty work replacing leaking seals. The sealant requires absolutely clean (no traces of oil) surfaces and no movement while curing to make a durable 'stuck to metal' joint. The need for absolute oil free surfaces {immediately adjacent to well oiled surfaces} and no movement during curing is not compatible with the assembly line operation. Oil will quickly spread from the oiled to the 'clean' surfaces via capillarly action unless the 'silicone sealant' wets the clean surfaces immediately. Good Luck in achieving those requirements on any assembly line.

dweb4

I finished project today. Oil cooler wasn't too hard to fix. The oil filter housing assembly took a little more effort. The hardest part was taking the belt tensioner off, to get to the lowest bolt on the filter assembly. I didn't know I had to put leverage on the tensioner to get under tensioner wheel mount to get that bolt. I got everything off and got the engine block and all the surfaces cleaned it went back together pretty well. So far no leaks will continue to watch. Thanks all for the help, it was job that took a little bit only because I took my time. Definitely saved a ton of money from having to pay stealer-ship to do it.