Big oil leak. Oil filter housing gasket? * now fixed *

J

JimCosworth

Member
Found a big oil leak after driving and engine oil was down. Took about half a litre to get it showing on the dip stick and no oil light on the dash so hoping it hasn’t harmed the engine. It sounds okay.

It was dripping from the oil plug inspection hatch in the under tray with a drip every 5 seconds.

The undertray is covered in oil and I’ve had the air filter off and I can see oil on the waffle structure on the block close to the oil filter housing gasket. From people’s experience does this sound like the problem? Is there anything else that could account for oil pooling there?

I started it up today with the air filter off to see if I could see the oil running down but for the 5 mins it was running I didn’t
see any leak but maybe the oil being thicker when cold it wasn’t seeping past the gasket?

Thanks in advance.

IMG_0853.jpeg
 
Thanks, that’s a relief. I think I should be able to sort it as doesn’t look too complicated. With the air filter and radiator cover off it looks like pretty good access to the alternator tensioner, alternator and filter housing. I’ll change the belts whilst it’s off.
 
Good shout

The bit that always causes dramas is getting the alternator to line up again on the lower bolt holes
 
Thanks, that’s good to know. It’s not my main car so if I don’t get it finished in a day it’s not a problem as I can just take my time with it.

Thanks again.
 
JimCosworth said:
Thanks, that’s good to know. It’s not my main car so if I don’t get it finished in a day it’s not a problem as I can just take my time with it.

Thanks again.
Click to expand...
Assuming N52.
I did it over a few days during COVID. It's a straightforward job, though you need quite a big torx bit for the tensioner.
Alternator bolts are single use.
Do both gaskets while you're there, I used OE as I didn't fancy doing the job again. Also a good time to do an oil change and a coolant flush and change. The elec pump makes flushing easy, just make sure you have power supply.
 
Steve is referring to the N52 engine that the oil filter housing also has a coolant water section on it that also has a gasket separate from the oil filter housing gasket. What year is your Z4 and what are the last seven letters and numbers of your Vin number so you can check on realoem parts site what is on yours. If its an E85 engined version then it will only have the oil filter housing to engine block gasket.
 
N52 parts diagram here https://www.realoem.com/bmw/en/showparts?id=LM52-EUR-06-2009-E89-BMW-Z4_30i&diagId=11_3753

M54 Engine diagram here https://www.realoem.com/bmw/en/showparts?id=BT52-EUR-06-2004-E85-BMW-Z4_30i&diagId=11_2201
 
Thanks for everyone’s advice. I changed the gasket today. It took me about 4 hours, mainly because it took me ages getting the alternator back on. The old gasket was totally flush with the filter housing and also had a break in it at the bottom so was in pretty bad shape.

IMG_0919.jpeg

Fingers crossed this solves my oil leak 🤞
 
bigwinn said:
I did warn you…

Good job well done
Click to expand...

You were spot on! I spent an hour trying to get the lower bolt in. I found the best way is to keep the top bolt out and try to align the lower one first. With a bit of wiggling it eventually went home.
 
One last thing - does anyone know the correct torque settings for the two alternator mounting bolts please? I’ve seen a few sites saying 21nm but then seen other higher figures as well.
 
For anyone in the future looking to do this the torque settings are difficult to find. For the M54 it looks like you need 21nm for the lower bolt and 45nm for the upper bolt which also holds the idler pulley (not the actual alternator pulley itself which is something like 70nm).
 
This is driving me nuts now. Changed the filter housing gasket and oil still pooling in the waffle structure on the side of the block. I’ve had the vanos oil feed off and looked okay and replaced the banjos with new crush washers both sides of the banjos. The pipe and connectors feel dry so I’ve rolled that out.

Is there any thing else that could possibly be causing this oil leak? If not I’ll have to get the oil filter housing off again and re-do the gasket although I’m sure it was done properly first time.

Pulling my hair out so any suggestions welcome!
 
If it hasn’t sat properly that may be one reason

Also I’ve seen it before that the torque settings were not tight enough… but obvs be careful…!
 
Thanks. Just looking at the diagrams and there should
be two locating dowels diagonally opposite each other on the housing. Mine only had one. I wonder if it is slightly out when I bolted it back up. I’m going to take it off again and re-do it.
 
You must log in or register to reply here.
Back
Top Bottom