Hi All. New member here. 2010 ML350 Bluetec purchased earlier this year. I love it.

But.... it has recently developed a sudden, somewhat substantial oil leak that doesn't seem to match any descriptions I can find in the posts. Can anyone explain what has happened to me?

It leaked when running only, still has enough oil to show on the dipstick. There is oil all over the passenger side of engine from the fill cap backwards. It was first noticed on the ground, coming out of the drain holes on the undercarriage tray. When I opened the bonnet it seems to have sprayed up and gotten around the top cover, pooled in the rubber gasket/cone around the oil fill, and covered to some extent most parts on the p-side. My best guess is that the leak was from above and dripped onto something that sprayed it upwards but here is no oil on the fans or belts. Could the alternator do that? Crankshaft?

It does not seem to be coming out of the oil filter housing or the power brake booster vacuum pump. Can the big ugly culprits (oil cooler and /or turbo gaskets) create this kind of mess?

I am 99% sure the fill cap was on tight. I checked the o-ring on it and it seems fine.

I'm baffled.

Many thanks to anyone who can tell me what happened.

J

PS - what is an oil cooler + turbo gasket replacement worth where you are? The first place I checked here (vancouver canada) quoted 3500 ($C). Yowza.

 

Welcome! Sorry to hear about the oil leaks. Have you used the search feature on this site? Bluetec oil leaks are common, unfortunately.

To me it sounds like the oil cooler. From posts on this site, it seems like the oil cooler can be done DIY, and it is a tough job. That also explains the dealer price.

After you do some searching, and if you can post photos, it will help others narrow down the leak cause for you and identify your options.

 

Thanks Chassis.

I have looked through quite a few forums and there is alot of great stuff about the dreaded oil cooler. But I'm still confused why the oil has been sprayed around the engine compartment with such vigor in my case. I hope someone can still answer that for me and tell me where I'm leaking from. I now think I have multiple leaks. I cleaned everything down quite thoroughly, topped up with a bit of fresh oil, and went for a drive. There were several spots of leak when I crawled back under which I cleaned up a second time thinking it might have shaken loose from some hiding spots after warming up and vibrating about. But after a second 10-15 minute run about I put it up on stands again and found oil in the same (several) locations.

Pics:




beads of oil appear at the notch about 10 seconds after wiping clean (while running).


What is this black canister piece anyway?

And from above dripping onto and past the alternator.

wtf?

 

You have found one or some of your leaks, if they are actively seeping/weeping/sweating/leaking.

Do more investigation and cleaning until you positively identify all leaks. Then you can create a game plan to address them.

One option for the game plan should be to sell the vehicle.