I have engine oil leak

[nariusb]

to track down. Valve cover gasket is done. Can it drip down from the loose screws of the pulse generator bracket, #10 in the picture? It seem to be comming from the area.

http://www.realoem.com/bmw/showparts.do?model=HC23&mospid=47402&btnr=11_0436&hg=11&fg=10

[Robert K]

The 3.5 liter engine is notorious for leaking oil at the crank position sensor mounting bracket bolts. The bad news is that unless you take the harmonic balancer off, you cannot get one of the bolts out. There is something you can try though. First, go ahead and remove the crank position sensor just to get it out of the way. Then remove the one bracket bolt that does come out. For the one that's behind the harmonic balancer, you have to take and end wrench and back it out little by little. It's best to work at it from the bottom after removing the plastic cover that's under the front of the engine. When you've got the bolt backed out as far as it will go, get a small paint brush and use some type of solvent to clean the front and back of the bracket, the timing chain cover, and the underside of the head of the bolt. Once you've got everything cleaned as well as you can, try coating the area between the timing chain cover and bracket with some type of gasket shellac. You'll also want to coat the front of the bracket where the bolt head will seal against it. Coat these same areas for the bolt you removed. After you've coated as many of the sealing surfaces as you can, put it all back together and tighten it down. This will do about as good as anything. However, these bolts do tend to back out every so often. So you might have to go back and check them occassionally. This won't fix it permanently, but it will either stop or reduce the leak for a while. It's frustrating, but I've gotten used to finding some oil in the underbody tray.

Grace and peace,

Robert K
1991 535i

[nariusb]

for taking time to answer my consern. I'm just wondering if theres any difference in this regar bettween m30 and mine m20? Would your instructions apply to my 525i with m20 baby 6 engine?
I will attemp to seal it. Would automotive silicon sealer work or should I stick to shellac?




The 3.5 liter engine is notorious for leaking oil at the crank position sensor mounting bracket bolts. The bad news is that unless you take the harmonic balancer off, you cannot get one of the bolts out. There is something you can try though. First, go ahead and remove the crank position sensor just to get it out of the way. Then remove the one bracket bolt that does come out. For the one that's behind the harmonic balancer, you have to take and end wrench and back it out little by little. It's best to work at it from the bottom after removing the plastic cover that's under the front of the engine. When you've got the bolt backed out as far as it will go, get a small paint brush and use some type of solvent to clean the front and back of the bracket, the timing chain cover, and the underside of the head of the bolt. Once you've got everything cleaned as well as you can, try coating the area between the timing chain cover and bracket with some type of gasket shellac. You'll also want to coat the front of the bracket where the bolt head will seal against it. Coat these same areas for the bolt you removed. After you've coated as many of the sealing surfaces as you can, put it all back together and tighten it down. This will do about as good as anything. However, these bolts do tend to back out every so often. So you might have to go back and check them occassionally. This won't fix it permanently, but it will either stop or reduce the leak for a while. It's frustrating, but I've gotten used to finding some oil in the underbody tray.

Grace and peace,

Robert K
1991 535i

[nariusb]

Today I followed Roberts instructions and sealled the branket and bolts with shelack sealer and a blue thred lock. No more leaks!!
Thanks Robert.

[nariusb]

Today I followed Roberts instructions and sealled the branket and bolts with shelack sealer and a blue thred lock. No more leaks, which looked pretty bad with hints to head gasket!!
Thanks Robert.