Unidentified oil leak

[jeffbebe 1560]

I finally got round to replacing the oil filter housing gasket which had been slowly leaking oil for a while. My mechanic also noticed a leak from the rocker cover so replaced the gasket at the same time.

Topped up 4L of oil as well (lost since it was refilled in March). Thought I'd got all the leaks but parked outside my office today for a couple of hours and came back to a pretty substantial pool of oil. Took it back to my mechanic and he got it up on the hoist but not obvious where the oil's coming from so gave it a good clean then ran the car for half an hour and got it back on the hoist. The only thing we could spot was a small leak from the oil sensor which I'll replace but not nearly enough to account for the big pool of oil when I parked.

No leaks after that until I parked at home - then a sizeable pool has appeared. The only thing I can think of in common with the earlier situation is that both times the oil has leaked are when the car is parked on the camber so it's leaning down towards the passenger side.

I'm guessing it hasn't leaked before because the oil level was lower... Any ideas what might be leaking when it's at an angle?

Gonna get it on the hoist again in the morning to see if we can spot it now the underside's been cleaned but any tips/ideas would be appreciated.

[hotwire 352]

Do you mean you added 4l of oil? If so - that is 2/3 of its total (6.5) so that is a hell of a lot to be low, surely a low oil level signal would have come up?

Sorry no idea off hand as to where it may be coming from

[_ethrty-Andy_ 2132]

is there a golf ball sized hole in the side of the sump?????

[jeffbebe 1560]

Do you mean you added 4l of oil? If so - that is 2/3 of its total (6.5) so that is a hell of a lot to be low, surely a low oil level signal would have come up?

Sorry no idea off hand as to where it may be coming from

Oops typo... Added 2L. Still sh*t loads and no obvious leaks prior today apart from Rocker head gasket and oil filter housing and those didn't seem to be p*ssing oil.

is there a golf ball sized hole in the side of the sump?????

ha! Nothing so easy to spot unfortunately, though hopefully easier to fix!

It's weird... Got my mechanic stumped too.

Edited October 4, 2012 by jeffbebe

[camera doctor 25]

Has it leaked since a filter change ?? My 530i leaked pools of oil after a filter change - the rubber seal on the new filter element was faulty, put the old seal in place, all good.

[BM WORLD 1283]

in the past i have found the m52 leak from the gasket between the oil filter housing and the block

also the little o-rings in the side of the housing .

the rubber gaskets and o-rings go hard

[*Glenn* 854]

Common leaks:

Rocker cover gasket

Oil filter "O" ring seal

Oil filter remote housing

Vanos hose

Loose vanos actuator

Loose timing chain tensioner

Cracked or broken breather hoses

Oil separator valve

Dipstick breather hose

Front crank seal

Sump gasket

[jeffbebe 1560]

Thanks for all the help, fellas.

Got the car up on the hoist again this morning and isolated the problem. Definitely the oil level sensor. Doesn't drip much on the flat but there's a steady trickle when the car's leaning on passenger side. I'm guessing the sensor's faulty anyway as I got no warnings and the oil level was pretty low.

BMW NZ want close to $300 for a new one but should be able to get one much cheaper elsewhere.

[*Glenn* 854]

I've never seen one leak like that before. They normally leak from the seal or plug. A faulty sensor won't trigger the engine check light, but the fault will be stored in the DME or Kombi memory though and would be picked up at service time if the service is carried out by someone who knows what they are doing

Edited October 5, 2012 by *Glenn*

[jeffbebe 1560]

I've never seen one leak like that before. They normally leak from the seal or plug. A faulty sensor won't trigger the engine check light, but the fault will be stored in the DME or Kombi memory though and would be picked up at service time if the service is carried out by someone who knows what they are doing

Hard to see exactly where the sensor is leaking - most likely the o ring's buggered. No faults when I scanned yesterday though?!

Edit: I forgot Kombi

Edited October 5, 2012 by *Glenn*

[antil33t 90]

replace the level sensor seal first I reckon... they are like $4.50 from the dealer.

was leaking like a pig on my E34.

also did thermostat housing seal and pressure sensor seals.. pretty easy job once you get started.

Edited October 7, 2012 by antil33t

[jeffbebe 1560]

replace the level sensor seal first I reckon... they are like $4.50 from the dealer.

was leaking like a pig on my E34.

also did thermostat housing seal and pressure sensor seals.. pretty easy job once you get started.

Good advice, thanks. I found a brand new sensor for $40 from Germany, so will fit that when it gets here.

[antil33t 90]

I have a spare one in the M52 that's in my garage also no good to me as E39/36 M52 has back sump, where e30 needs front sump does not appear to be leaking.... Brand new is better, though.

Edited October 7, 2012 by antil33t