Hello All, started to notice a sudden and urgent oil leak from the M278.

started with a few drops but moved to a consistent drip when on, which means it’s under pressure.

took a look and started removing things and it seems to be from the Oil filter housing or cooler itself. My guess is the housing since the oil seems to coming from higher up

My local dealership has the gaskets for both and that’s what I think i will replace. Anyone have a reason to replace the whole housing assembly?

any feedback would be appreciated.

 

Same issue here, I went to the local shop who work with these engines and saw nine other 63s and 550s with similar leaks. The told me to wash the engine (front) and drive it for a while so we could see where exactly the oil is leaking from. Very common issue on m278 engines for some reason. I would not be too concerned as long as you keep adding oil to it and it does not drip down to alternator.

 

For an update, I ended up replacing quite a few seals and took most of the front end of the engine off. This was quite the undertaking but I am happy with how it turned out and it ended up savings me tons of $$$ compared to the dealership charges.

Here is the thread I used from the W212 E63 forum which has tons of Mercedes Work Instruction PDFs on it, it was an invaluable resource. Post #114 and #116 have the main ones you need.
E63 S 4Matic M157 | Factory WIS Maintenance and repair documents - Page 5 - MBWorld.org Forums

What I replaced:



Timing Cover Seals/Camshaft Gaskets, pretty simple, uses RTV to seal and new aluminum screws (000000006365) ($10 each, I didn’t replace all of them, only the lower ones as they seemed to have more of a sealing function), remove the Camshaft adjuster magnets and replace the O-Rings (0169975045) ($5 each) and screws (0009903924) ($3 each), they are aluminum and break easily with thread locker on them.

Oil Cooler Gasket (2781840080) ($20), or use the Elring Klinger part, it’s the same as the dealership part but cheaper. This job was not too bad, remove the belt/tensioner, 4 screws, pull it off, coolant and oil comes out, clean off the sealing surfaces, put the new gasket on, reattach

Oil Filter Housing, this was the worst jobs of all of these. It requires a lot of removal of other parts just to get to it, and is not a fun job overall. You must remove most of the front end, Covers, Belt, Fan (if you want more room), Thermostat Housing (replace the O-Ring (0229976445), draining coolant, remove Charge Pipes, Turbo Coolant Lines (Thankfully I only broke 1), Radiator Pipes, tons of screws holding things on, it was really a lot of work with uncomfortable angles and not much room

I talked with my dealership and they said they typically just replace the Housing (2781800710) which is a $200+ part. It’s a well made part and has 4 points of leakage, and I replaced these instead of the entire housing which saved some $$$

Oil Filter Cap (shouldn’t leak if you replace the O-Ring (0209975445) during oil changes and don’t over torque the cap.

Oil Housing Cap (pressure relief) (2781800438) ($30)

Oil Filter Housing Main Seal (2781840280) ($10)

Oil Distributor Screw (001-997-20-01) ($10), I Stripped mine when removing the oil distributor/sensor which is why I had to replace it. Strangely enough this part doesn’t show up on the CLS or E550 M278. Only the 2015+ S550 and S63.

Hopefully this helps someone, let me know if you need more information or tips.

 

Timing sensor covers commonly leak, sometimes destroying the harness underneath.