Massive 4.8L Oil Leak - See Picture - Help Needed
 

My 4.8L dumped 4 liters of oil in less than 5 miles yesterday. Bless my wife's heart, she obeyed the computer and stopped driving immediately when the critically low oil warning appeared. The car is back home over the pit, and now I'm trying to sort out exactly what the source of this leak is.

When the engine is running, oil comes in a steady stream from between the engine and the front differential (driver's side of the engine). From below, looking up between the differential and the engine, the leak is higher up than I am able to see - above the highest visible mounting bolt for the dif (see photo). I am unable to see the area of the leak from the front of the engine. I've removed the inner fender, but can't see it from the wheel well. I've removed the intake and the air dam and just about every other reasonably easily removed part, but I can't see it from above. There seems to be no easy way to get eyes on the leak.

https://fbcdn-sphotos-h-a.akamaihd.n...47d6580d097150

Two questions for the experts:

1. Any thoughts on what might be the source of such a prolific leak in this area?

2. Any ideas on the easiest way to get in for a better view of what's above the differential?

I'm a licensed mechanic, so I'm not worried about doing whatever is needed, but I'd really love to avoid any more unnecessary disassembly as I try to sort out what the problem is.

Thanks in advance!

Justin

That is scary, I have no idea, I'm glad the motor was not ruined, I hope you sort it easily & welcome!

Alternator bracket gasket. Also the gasket to nowhere.

Thanks e30cabrio. I've been a longtime lurker here on these threads and have found a lot of great info here over the years, but this one finally forced me to join :D

Yes, I' very grateful my wife shut the engine down immediately. I have heard of others who were not so fortunate. I don't mind doing a lot of work to fix an oil leak, but a total engine rebuild is another matter altogether!

Oh, and I should have mentioned... it's a 2008 E70, 4.8L with the cold weather and sport packages.

Thanks again!

Thanks gregg3gs. Yes, I read about the "dreaded alternator bracket" in another thread and wondered if that might be it. It's an incredible leak for something so trivial, but I have seen elsewhere failure of the alternator bracket gasket can result in a pretty bad leak.

Is it worth diving in and pulling the alternator, or are there other likely candidates in the same area?

make sure the hoses that go to the oil cooler are nice and tight.. those will leak out all the oil very fast

Subscribed. My wife's 08 4.8i is leaking from the exact same area, albeit minor at this time. I too could not see source of leak, but immediatly assumed alt bracket. I have done this type of repair on my '04 545i. my wife's X5 has active steering, sport, dynamic whatever, so all possible obstructions are present. Not gonna be fun. Keep us posted on progress of this discovery and repair so I/we can know what to look for and/or avoid.

good luck.

Thanks again, gregg3gs; you nailed it. Gasket was cracked. What a royal pain to get at!!!

For those who are watching a slow drip, don't put it off. I made a note about a small leak at my last oil change, which was less than 2k miles ago. Given how dramatic the leak was, I feel very fortunate to not be doing a full engine rebuild. As catastrophic a leak as I have ever seen. It was literally a stream coming out, not drips.

Also, I did manage to get this done without lifting the engine, dropping the sub-frame, or pulling the front differential. I used a ground down socket, reduced to 1/4" drive. No universal joint either. Just a short 1/4" drive extension (see picture). Still a terrible job, but not nearly as bad as hoisting the engine and separating the front drive gearbox.

https://fbcdn-sphotos-d-a.akamaihd.n...4a6579f707253d

Good luck to you all. Let me know if you have any questions. And thanks again for those with the expertise to point me in the right direction.

If you're taking this job on, check out this Pelican BMW tech article. I found it very useful.

Thanks for this as well. Going to put all new O-rings in all of the tube joints and will double-check they are secure.

Cheers!

Care to share any other details. What's the front diff an issue as related to write-ups for 2wd cars? How long did it take you?

Front gearbox would obviously only be an issue for cars with x-drive. But a ridiculous job, even without pulling the front differential.

It took me 5 hours to get the gasket out. Granted, I was meticulously cleaning the oil mess as I went, which is a personal thing. And also, I pulled the LH inner fender for vision to the gasket, which I think was unnecessary. Regardless, I'm a fairly experienced mechanic and people who claim they can do this job start-to-finish in just a few hours (I've seen claims of 2.5 hours) are simply not credible.

Now that I am familiar with the job, I think I could do it end-to-end in 4-5 hours. BMW book value for this job is 9 hours. It would be very difficult for someone who has never done this job before to get it done in under 8 hours, IMHO.