M42 Oil Leak from lower half of engine? Help?

[HairGel]

Hey guys, I have a 318i (M42B18) basically stock and I noticed there was some oil leak underneath the car, I cleaned the area around the head gasket and oil filter to check if it was coming from there. After a couple of days, I checked again and it was clean, but the leak still occurred. I looked under the engine bay and saw the whole subframe, oil pan, etc caked in dirt and oil.


The plan is to clean the lower portion of the engine bay then try to find the leak from there. But before I need to take out and disassemble the engine for one gasket I'm here to ask you guys a question.

Is there any common oil leak problems on this M42B18 on the lower portion of the engine? If so, which of those could I have based on these pics? How would I go about fixing it? Which gaskets? Labor intensive? Easy? Thanks, any tips would be appreciated!

[Thrifty S50]

Too much oil to pin point the "source". It is most likely a culmination of multiple leaks.

Without having to jump straight to the Oil pan gasket, which is the biggest pain to replace out of them all, I'd tackle these First:

Valve Cover Gasket, Oil Filter Housing Gasket, Power Steering Line Leaks. Clean your engine bay thoroughly after replacing those few and check back after a few heat cycles. If your still leaking then it should be easier to pin point where it is seeping from.

[Thomas525]

NO, don't clean anything. Get under the car and see where the oil falls FROM. It will not be any gasket above that line. It will be one or more below that line. After that, clean out your entire engine bay with degreaser and water - straightforward procedure. Then take another look a day or two later after driving. If you don't see any leak, take another look 3-4 days later.

[B320i]

With the amount of airflow through the front of the car - an oil leak from the oil filter housing (for example) could easily be spread all over the show. Likewise, a leak from the valve-cover can make it's way down the back of the engine.

[Thomas525]

Yes, but in that case the oil will not be above the oil sump line and the valve cover gasket line. Oil does not flow up or get pushed up by air.

[B320i]

Yes, but in that case the oil will not be above the oil sump line and the valve cover gasket line. Oil does not flow up or get pushed up by air.

The oil will run down, and like water on a car, air movement (or the angle the vehicle is parked) will result in the seep moving in a particular direction. I didn't say it would flow up.