M50 Engine Oil Leak

[Spud]

I have an oil leak which I thought I'd fixed, but need some help…

Oil was collecting on the bottom of the sump near the oil level sensor, so I replaced that O ring and also replaced the dip-stick tube O ring, which was missing. I also replaced the oil stand seal along with the oil pressure crush washer.

Once I'd done all this the leak looked like it was fixed, but a couple of week later its come back and is collecting in the same place.

I'm pretty sure the sump pan seal is OK, although I've noticed oil around a cover plate on the oil stand. This is held in with a snap ring, but I couldn't find any reference to a replacement seal on realoem, so if that's the source how do you fix it?

Any ideas as to the cause?

[fujioko]

Sounds like the oil filter housing gasket is leaking. This is a rubber type gasket under the aluminum oil filter housing. Its apparently common for the gasket it get hard and start leaking on the M50. (happened to mine a few months ago)

The replacement gasket runs about $9.00 at the dealer.
This is a DIY for most folks and takes about an hour and a half for a newbee
and less than 45 min if you familiar with the M50.

As I recall, someone else did a write up on the procedure. I found it very handy. Perhaps a quick search will yield some instructions if needed.

I truly value this site for the vast amount of information….and of course the comical relief.

[Mendozart]

You can got to members list and find Bill b. He's the one with the write-up, click posts by this member. I just printed this one up last week. Or do a search (oil filter housing).

[Spud]

Guys, thanks for the feedback.

I checked the link and I've already replaced the oil filter O ring between the filter housing and the block. But the casting dosen't have the same oil pressure switch mounting, it just screws into the casting, so I don't need the other o ring type seal. The engine isn't a vanos unit either so I'm perplexed as to why the housing is different. There's also no obvious cracks or damage...

[Spud]

Found the source of the leak. The 22mm "o" rings used to seal the two aluminum caps on the casting, held in place with snap rings, were shot. I repalced these and the leaks gone away.
I should have done this the first time, so if anyone's repalcing the oil filter housing gasket and has this design casting then make sure you replace these "o" rings as well. Easier that doing the job twice...

[GoldenOne]

haha wierd...i had that same problem on my old m50 engine...now i know what to check on the new one..

[Mendozart]

Hey Spud, I'm going to be doing my oil filter housing gasket this week. Where exactly are these "o" rings? Any part #? I want to have everything when I start. What year is your car?

[Spud]

Hey Spud, I'm going to be doing my oil filter housing gasket this week. Where exactly are these "o" rings? Any part #? I want to have everything when I start. What year is your car?

Greg,

My car is a 92 with a 9/91 production date.

Its confusing because there appear to be two types of filter housings on the M50 engine, unless what I have is some sort of mixture.

The one on realoem for this year shows the main o ring, which seals the housing to the block (11421719855), and a second smaller deal (11421738409) that seals a secondary casting for the oil pressure switch. My version only needed the larger one since the oil pressure switch is screwed straight into the filter housing itself, sealed only with the copper washer. If your isn't like this then as far as I know you don't need the other o rings.

However if it is then you'll see two aluminum disks about 1" in diameter recessed into the filter casting, 1 above and one below the oil pressure switch port. They are both held in with a snap ring. When you take the casting off you can see them clearly and all you need to do is carefully pry out the snap rings, taking care not to damage the casting in the process and making sure they don't fly off in to the distance… Once you've got them out of the way the cap can be removed and you should be good to go.

I got the 22 mm o rings from a auto parts store for a couple of bucks and they seem to be a standard metric size. The ones I took out were noticeably smaller, which worried me a bit, but then it was leaking oil wasn't it! Anyway, I lubed them up with fresh oil and they snapped right in... I put everthing back together and it seems fine.

Hope this helps

Spud

[Mendozart]

Thanks for the info Spud. My car is a 6/92 production so I'll just get the housing off and see what I got.