E46 Fanatics Forum banner
1 - 11 of 11 Posts

· Registered
2003 330ci convertible
Joined
·
80 Posts
Discussion Starter · #1 ·
Is there any possibility that replacing an alternator could cause the oil filter housing to start leaking? The Battery Charge Warning Indicator lit up so I took my 2003 330Cic with 71,804 miles to my usual mechanic who said I needed a new alternator and replaced it. A few weeks later I took it to my preferred BMW dealer to get my annual "Value Oil Change". My advisor sent me the following video to explain their findings: ServiceCartApp
Everything he said was known to me except the oil leak. When I got home I checked but saw nothing. My car gets a BMW oil change and an indy PA State Inspection every year and this has never been noted before. Is it possible that this leak could have occurred because of the alternator replacement?

Thanks in advance,
Bob
 

· Premium Member
Joined
·
5,137 Posts
Yeahbut...

the oil filter housing LOVES to leak if you look at it funny,
don't look at it,
video it,
or even think about it.

So yeah, bolting a new alternator to it MIGHT have caused it to let go,
but it's likely it'd have started leaking anyway when you next saw
Oil Filter Housing written somewhere.

It's a $6 seal.

t
 

· Registered
'04 325i, '02 325iT
Joined
·
1,851 Posts
Replacing the OFHG is not that difficult of a job, but it is one of those "while you're in there" things where you might as well replace a bunch of other stuff at the same time.

The top bolt for the alternator also mounts the drive belt idler pulley, so you'll want to replace that rather than reinstall the old one. And if you're replacing that pulley, you should also replace the pulley on the belt tensioner.

With the alternator and oil filter housing removed, you'll have much better access to the CCV and related hoses, so it makes sense to replace those if it hasn't been done recently. Replacing the CCV requires removal of the two rubber air intake boots, and those are known to crack and cause vacuum leaks, so might as well get new ones. You'll also need to remove the throttle body, so you'll need a new gasket for that.

And removing the OFH also requires disconnecting the VANOS oil line so at minimum you'll need new crush washers, but there's a high likelyhood that hose is weeping oil if it's still original, so might as well replace it.

And while you're fixing oil leaks, might as well replace the valve cover gasket too, because you know that's going to start leaking next after wiggling it around to remove the CCV hose you just disconnected.

And that's how you end up down the rabbit hole, and a $3 OFHG turns into below. Because, you know, might as well do brakes, coils, and filters too.

Automotive parking light Tire Vehicle Wheel Land vehicle
 

· Super Moderator
Joined
·
3,125 Posts
If you don't know when the oil filter housing gasket was last replaced, or if it's original (which sound likely), then it was simply due to be replaced.

The gasket becomes brittle with repeated heat cycles and will lose the ability to seal regardless of mileage.

I suggest you have it replaced and drive on.
 

· Registered
330ci Coupe 6MT
Joined
·
1,934 Posts
I'm reminded of youtuber Hoovie's mechanic "the wizard" who thought that the oil filter housing on an E46 is just an alternator bracket, and took it off to change the alternator. And dumped oil all over his customer's engine and his shop floor. If the OP's shop also weren't familiar with BMWs, also didn't RTFM and did the exact same thing then maybe they put it back together with the old gasket, and it didn't reseal properly having been disturbed. Just a possibility.

But it could equally be a coincidence. LIke others have said, its time could just happened to have been up a few days after they did the alternator.
 

· Registered
2003 330ci convertible
Joined
·
80 Posts
Discussion Starter · #10 ·
I'm reminded of youtuber Hoovie's mechanic "the wizard" who thought that the oil filter housing on an E46 is just an alternator bracket, and took it off to change the alternator. And dumped oil all over his customer's engine and his shop floor. If the OP's shop also weren't familiar with BMWs, also didn't RTFM and did the exact same thing then maybe they put it back together with the old gasket, and it didn't reseal properly having been disturbed. Just a possibility.

But it could equally be a coincidence. LIke others have said, its time could just happened to have been up a few days after they did the alternator.
That is what I was thinking. But my shop does many different marques including BMWs and the owner has had a few E46s, so? I have to drive it more to see if I can find the leak.
BTW: The dealer estimate to repair was between $1,000 and $2,000.
 
1 - 11 of 11 Posts
Top