Oil Leak

[6670charger]

How common is it for the oil filler cap on the E30 M20 to leak? Have an oil leak I'm trying to trace down, and figure it should only be coming from a handful of places.

 

Thanks.

[jc43089]

I have replaced them because of loose fitment. The rubber ring deteriorates over time. I usually but the cooler looking M cap. The caps for different bmws are interchangeable.

Sent from my potato phone

[straight6pwr]

it can leak, sure.  but why are you asking? stand there and look at the cap and see if its leaking. if there's oil around it, it cant be dripping from your hood...

[B C]

Like jc I have replaced mine due to loose fitment, more of a vac. leak issue for me than an oil leak issue.

Possible sources:

Oil cap

Valve cover gasket

Rocker shaft plugs

Cam seal

Head gasket

Bish tube o-ring

Intermediate shaft seal

Crank main seal

Oil filter housing o-ring

Oil cooler fittings

Oil pressure sender

Oil pan gasket

Oil level sensor gasket

Oil pan drain plug

TV/VCR repair

Or get your degree

[KaiserRolls]

UV dye it

[6670charger]

UV dye it

That's probably the best solution mentioned, since it seems there are so many places it could be coming from.

 

Thanks.

[6670charger]

Alright. I've done some research and hunting around under the hood, and this is what I've come up with so far: I had a brief period this afternoon when I wondered about a blown head gasket, as the car overheated briefly a few months back when I was out of town and broke my fan belt. However, I'm not getting any smoke or anything else unusual out of the tailpipe, the dipstick oil is plain black, and the parts I can see under the valve cover using a really bright flashlight appear normal, as in no milky looking oil or sludge. The engine makes good power, runs normally, and has not lost gas mileage at all.

 

There seems to be some oil on the passenger side of the engine, but looking under the car, it seems to be dripping more in the center front. so now I'm thinking cam seal, drain plug, or something else in front of the engine. It doesn't seem to be the valve cover gasket, as there is no fresh oil showing anywhere along the edge of the valve cover, and although the top of the valve cover is dirty, it isn't oily so it shouldn't be the cap as I had wondered. I am getting some dripping along the rear of the engine on the passenger side, although all the fresh looking oil seems to be along the bottom edge of the engine, so wondering if leakage toward the front is blowing back due to air flow while driving?

 

Will have to drive her up on ramps tomorrow and do some cleaning and more in depth looking. Think I'll take the plastic shroud off and leave it off for a few days so I can see exactly where it's dripping from. My hope is that it isn't the cam seal or something like that as I just replaced the timing belt about 20K miles ago, although I guess I wouldn't necessarily have to change out the water pump this time around at least.

[B C]

 

It's not unusual....

 

..... for an M20 to have an external head gasket leak. The oil return drains are on the passenger side of the engine there. 

[straight6pwr]

An oil leak won't cause overheating, but a broken fan belt sure could.

I drove my e30 m20 car from 145k to 245k miles with oil leaking from the front of the engine same as you. Doesn't affect anything unless you care about the cleanliness of your parking spot.