Hello. There are common oil leaks on the OM642 platform. One of those leaks is the oil filter housing gasket. It's normal for it to fail and I'd bet good money that's where your leak is coming from.

This is the gasket:

Mercedes Oil Filter Housing Gasket - Elring 6421840080

Mercedes Oil Filter Housing Gasket - Elring 6421840080

www.fcpeuro.com

Oil filter housing:

Mercedes Engine Oil Filter Housing - Genuine Mercedes 642180141064

Mercedes Engine Oil Filter Housing - Genuine Mercedes 642180141064

www.fcpeuro.com

If you decide to buy the oil filter housing, then it will come with the new gasket installed already, fyi. GL.

 

Thanks, I'll investigate that. The location it's showing up at would correspond with the filter housing so I suspect you're right. I think I'll do the $5 gasket instead of the $145 housing...

 

I have the same problem, with oil dripping off the bolt under the AC compressor. It has gotten severe in the last few days and now there is an oil stream when the engine is running. I've had to add 4 quarts of oil over the last two days. My ML320 is a 1999, so the above listed gasket will not work, since it is for 2007 and above. I have read other posts on this problem and most recommended the genuine Mercedes gasket over aftermarket gaskets, claiming they tend to leak again fairly quickly. I actually ordered the oil pressure test port cover and gasket today from Mercedes but cancelled it when I clearly saw that it wasn't the source of the leak, although I can't actually see the leak. I also see that you need a 46mm socket to get out the hollow bolt holding the housing to the timing cover and that, because the bolt head is very shallow, you cannot have too much bevel on the inside of the socket. The only sockets I've been able to find like that are axle nut sockets, which are very expensive at over $50. In addition, I'll need a 3/4" breaker bar, a 3/4" extension, and a 3/4" torque wench, since all the suitable 46mm sockets I've found are 3/4" drive. Thus, the tools needed for the job will likely approach $200. Before I spend that much on tools I will only use once for this job, I'd like to know if there's a way for me to ensure that this leak actually is the oil filter housing gasket. Thank you for any advice.

 

Not a whole lot of help, but, I have a 3/4" to 1/2" adapter and no 3/4" tools other than a couple of sockets.

Lowes carries the Craftsman version for $12.98.

 

Yes, I'll probably try to find 1/2" to 3/4" adapter, since I have a 1/2" extension somewhere, a 1/2" ratchet, and a 1/2" torque wrench. I'll still need a 1/2" breaker bar. I've been eying an extendible model. I have the 3/8" version and I use it a lot. It's nice to be able to fit it in the toolbox. Even if it's not long enough and I have get a longer one, I'll still use it a lot. I was a quart low this morning so I put in a quart of Lucas stop leak. It has good reviews and it may slow the leak until I can fix it. It works by conditioning and swelling rubber seals. I'm going to pick up some dye tomorrow to see if I can nail down whether the housing junction is the problem. I hope it is, since that's much easier to fix than a timing cover gasket.

 

It turns out that I will not need the adapter or the 46mm socket, because I do not have a 46mm nut to remove. Apparently, only the ML320s with an oil cooler have the separate filter housing that is held on with a 46mm nut. Only very early ML320s in the U.S. had the cooler. I pulled my filter a few minutes ago to confirm. I put dye in the oil yesterday, but I can't see anything yet. I believe that because the MLs have such a high oil capacity, I will need to put in two bottles of dye to allow it to be seen. I fear that the leak is from the timing cover, which will be much harder to change. However, I have seen a housing (see pic) that looks like it bolts to the timing cover. If my housing looks like that, perhaps the gasket shown is the source of my leak. The housing in the picture also seems to be two pieces, with the connection just under the actual round filter housing. Perhaps there is a gasket there that is leaking. So far, the source of the leak is still a mystery.

 

Hello. Can you take a picture of your engine bay and post it here...

 

I can, but it wouldn't show much. I now realize that the housing pic I posted is for a diesel, and that I am in the diesel forum. I have a 3.2L gas engine. The pic below shows the timing cover for that engine and it's obvious that the filter housing is cast into the timing cover. I suspect I will have to remove the timing cover to fix the leak, which is a huge job. It's possible, but unlikely, that the oil pressure test port gasket and cover need replacement. I say unlikely because when the engine was running, oil was streaming down from the bolt under the AC compressor. I got up and looked at the front of the engine, including the oil pressure test port, and there was no oil visibly streaming from anywhere. Those parts are about $45 from Mercedes, and replacing them is easy, but I hate just throwing parts at a problem and hoping something will stick.