Oil leaks and more oil leaks!

[mike.bmw]

I picked up a fairly clean-bodied '91 318is a few months ago. I've been working through a number of issues and now I'm onto the oil leaks. The M42 has 134K miles on it and doesn't burn any oil, but it will leave 6-10 drops of oil on the garage floor overnight.

I've replaced the valve cover gasket, spark plug tube gaskets, and valve cover fastener rubber washers with OEM BMW parts. I replaced these because the gasket was leaking and the spark plug tubes were filled with oil. 1,500 miles and no leaks here since replacing these gaskets.

I've replaced the lower oil pan gasket with a Victor Reinz gasket, which already leaks (even after re-torquing the bolts). While I was replacing the lower pan gasket I helicoiled 6 of the upper pan threads, chased all the others with a TAP, and installed all-new BMW hardware in the lower pan. I also checked the torque on the upper pan bolts and all were still good.

The upper pan gasket is leaking oil. The front timing cover is leaking oil. There doesn't appear to be any leaking *yet* from the rear main seal.

It's my understanding to replace the upper pan gasket I'll need to separate the engine and transmission so access two rear bolts on the upper pan. Is this correct?

I'm not sure if it's worth replacing the other gaskets at this point. I'll eventually need to replace the clutch. I assume this would be a good time to also replace the upper pan gasket?

[Balleristic31]

You definitely do not have to remove the transmission at all to replace the upper pan gasket, but you do have to lift the engine a bit to get the pan out. I used copper spray on the paper gasket and no leaks so far.

Also my suggestion on how to get the Lower gasket not to leak is to just ditch the gasket all together and use a good gasket maker (the right stuff, hondabond, grey permatex). Follow the instructions for those and you will be better off than with a paper/cork gasket.

[bmwman91]

There is a very good chance that none of your oil pan gaskets, or the timing covers, are leaking. It is most likely the o-ring on the oil filter housing. Pressurized oil gets forced out past it, which then blows all over the front of the engine making it look like every paper gasket is shot.

See my thread here:

http://www.r3vlimited.com/board/showthread.php?t=364806

Basically, here's what you need to do with the oil filter housing:
1) Replace the o-rings on the round outlet. Do not let ANYTHING fall into this hole because it is the clean oil feed for the engine, and anything that goes in there will end up in a lifter or main bearing. This includes silicone RTV, which you should not be using here anyway.
2) Clean that round oil inlet very well, along with the gasket surfaces. I like Acetone since it removes oil and gunk easily, and completely evaporates off. Wear gloves.
3) Get some Permatex High Temp Spray A Gasket (https://www.permatex.com/products/ga...asket-sealant/). You can get it at any parts shop. Apply a coat to both sides of the paper gasket and let it dry for 5-10 minutes before assembly. Don't let dirt or other crap get onto it. Do NOT use silicone RTV here since it could a) squeeze out into the clean oil passage, and b) force the gasket out of position as it is compressed.

Those are my thoughts. It can be hard to tell if the leak is coming from there since all of the seepage on the front side will run down the engine. There is a web in the block behind/under the filter housing where oil can pool, so get a look in there with a flashlight to see how nasty it is. Even when it looks clean/dry back there, the filter housing can still be leaking. It's a very common problem on the M42 and M44.

[roguetoaster]

Out of curiosity, what oil/weight are you using?

I ask as I have noticed that certain lighter oils I have used in the past have been more prone to seepage past gaskets, but running 15w-40 or higher seems to cure that problem on my M42.

[mike.bmw]

Out of curiosity, what oil/weight are you using?

I ask as I have noticed that certain lighter oils I have used in the past have been more prone to seepage past gaskets, but running 15w-40 or higher seems to cure that problem on my M42.

I'm using Rotella T6 (5W-40).

Thanks for the tip on the oil filter housing. It does appear the oil filter housing is leaking. I still think I might have timing cover leaks and upper pan leaks as well. The upper pan appears to have significant seepage on the right side of the engine (opposite side from the oil filter housing). The entire outside of the lower pan has a nice coating of oil on it as well.

The leaks certainly aren't the end of the world, but I'd prefer if there were none. ;)

[TobyB]

the oil filter housing.

This was my thought as well.

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