M54b25 Oil leakage

[McKHAANN]

Hi!

I have noticed that my e39 525i -03 (m54b25) is using some oil and I started to investigate into that problem, I saw right away that I have to change the VCG, so I am waiting for that to come! After some more investigation I saw that there was some oil residue on the right side, I will attach a photograph on where the leak is collecting, It is pretty hard to photograph that section so I will mark the places. The thing is I can't really find on the Internet where that comes from? From my research that I have done I think it's the Oil Pan Gasket but I am quite not sure? Is there anyone here that know what causes the oil leak this way that my car does?

[osc911]

Check the oil filter housing gasket, behind the alternator. And the CCV under the inlet manifold. Also check dipstick to lower oil pan orings.

The fan will blow oil residue backward and make a mess. Best to clean it with degreaser properly, then it's easier to see the source.

The other side is usually the rocker cover gasket.

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[JaxPlanet]

I agree with osc911. In addition, you might have some ATF fluid on that side of the engine because the hoses under the power steering reservoir, which uses ATF, are prone to leaking. You can tell the difference between engine oil and ATF by the smell. ATF stinks!

FWIW: Be very careful removing the valve cover because it is plastic and do not over torque the bolts when you put it back on. I like to warm up the engine before this job to make the cover easier to separate. I recommend that you replace the VANOS seals, if you haven't already, this procedure covers replacing the VCG and the seals: http://www.beisansystems.com/procedu..._procedure.htm

[cnn]

For M52 and M54 engines, always follow this sequence:

1. Replace OFH Gasket (BMW dealer sells the gasket for $6).
Follow tips in forum of torquing evenly, wait, then torque a bit again to prevent leak later.
My OFH Gasket leaked at 120K miles.

2. My VCG gasket leaked at 150K.

3. My oil pan gasket is still bone-dry at 170K miles.


cnn
1998 528i with 170K miles

[Mike WW]

One more whose guess would be the oil filter housing. It leaked pretty good for several years on my 00 528it, I was convinced it was the pan, I even changed the front crank seal. I even degreased it at the DIY car wash but failed to note it was the OFH gasket. They are definitely a known problem child.

VCGs are supposed to leak at 100K, or at least be replaced then. I have replaced several, but the original was never leaking up to ~150K. An aftermarket one was leaking at about 45K on my E36, so I would suggest a BMW one, not generic. And I'm not the guy who always say use only BMW parts, I've used lots of brands, usually with good success.

[djb2]

An echo of agreement.

The oil filter housing gasket (OFH gasket / OFHG around here) hardens and leaks after a decade or so. It sometimes subsequently cracks, resulting in rapid oil loss, so you should just live with the leak.

Always install with a torque wrench. Not because the clamping force is critical -- the gasket is in a groove, and the clamping force doesn't change how it seals. Use a torque wrench because some earlier knuckle-dragger might have tried to stop a leak by nearly stripping the threads from the block. If you find that has happened (it is quite common), a $10 eBay thread insert kit works fine to repair the damage. Do not try to use a longer bolt. There aren't enough extra threads and it has ended badly for the people that have tried.

There are good aftermarket VCGs. There are also counterfeits and horrible ones. The BMW VCG is much more expensive, but it is a superior product compared to even the good aftermarket ones. Buy it if you are risk averse or are paying a shop.

[Jason5driver]

When I replaced the oil filter housing gasket on my car, two of the bolts stripped out when removing them.
The bolts galled within the aluminum head.
The bolts pulled out small aluminum spring pieces.
I Heli-coiled the stripped bolts, which worked fine.