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Join Date: May 2005
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Oil leak after rebuild

Help. Just finished my first rebuild on my 930. Replaced the stock exhaust with SSI headers. I have a very small oil leak coming from the left side cam housing cover lowest stud just over the header.

I removed the cover, replaced the seal and use THE RIGHT STUFF gasket sealant on both sides of the gasket to make sure it would never leak again. However it does. Can only think of two reasons why it is still leaking. The housing covers are brand new because I bought the upgrade chain tensioners, so they shouldn't be warped. Plus the gasket sealant should fill any gaps.

1) The two lower studs came out (unscrewed) and I used bolts in those two lower locations. When I replaced the gasket, I replaced the bolts with studs. Unless they did not seat all the way, they should be as good as new.

2) The new headers run right under the leak. The headers were new and when I first started the car they were GLOWING RED, I assume from oils used when forming them burning off. Can the heat from the headers be warping the cam cover or melting the RIGHT STUFF sealant?

I have not checked the AFR yet because I can run the car long enough to get it warm without oil dripping on the header.

Please help with any thoughts. I don't know why I can't get this to seal properly.
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Old 10-18-2010, 04:57 AM
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Many oil leaks that look apparent are really coming from someplace else. It may be that your leak is not at the chain box to case joint. I would look at the cam carrier; it's the piece that has the o-ring and gasket under the cam sprocket. Some gasket kits have a very thin gasket that goes between the carrier and the cam tower and it's easy for this gasket to get pushed out during assembly. This joint is pressurized so it will leak if the gasket is not in just right.

Your bolt and stud issue is a non issue. Neither would cause a leak as far as I can see as the hole that they thread into is blank. I don't think your headers should be glowing red unless you are on a dyno WFO.

Lindy
Old 10-18-2010, 05:14 AM
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Is this the gasket that you are referring too?

It doesn't seem to be leaking from the case to cam housing gasket but the cam housing cover gasket. There is a small drip at the lowest attachment. It could have come from somewhere else (must have since I know I used plenty of sealant)

I'll keep looking.
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Old 10-18-2010, 08:59 AM
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Yes, that's it. Another thought is how tight do you have the nuts on the chain box cover? If they are overtightened it will warp the cover enough to leak. Max torque is 7.5 ft-lbs.

Lindy
Old 10-18-2010, 10:45 AM
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I torqued them all to 15 n-m using an "old style" needle torque wrench so I am a little high. The other side is torqued the same and it is not leaking.

I applied the gasket sealant to both sides of the paper gasket so it should really be sealed.

Stumped. I'll keep looking to see if the oil is coming from somewhere else. I really can't imagine that it can still leak with sealant on both sides of the paper gasket.
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Old 10-18-2010, 11:18 AM
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Spray the area really well with brake cleaner and dry with a towel. Start the motor and look under the car with a good flash light or drop light. See if there is oil at the point you think it's leaking first then start looking elsewhere. You'll find it.

Lindy
Old 10-18-2010, 12:16 PM
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Check to see if the oil could be coming from the stud itself. Sometimes a stud hole will be tapped through the housing. This would allow the oil to follow the threads of the stud and escape out below the nut or out the nut's threads.
I had a situation similar to this except it was a valve cover stud.....drove me nuts until I discovered what caused it. Try putting Lock-tite on the stud threads and reinsert the stud.
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'85 930 Factory Special Wishes Flachbau
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Old 10-18-2010, 05:37 PM
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Leaks anywhere in this general area tend to come off the low point of the exterior, as Lindy points out.

I once forgot to tighten the three 6mm bolts which hold the aluminum cam holder ring and its associated gasket and O ring to the cam carrier. Quite a leak. Not a gusher, but left drips on the pavement during the very short drive from garage to trailer.

Sometimes I have had (or thought I had) leaks where the chain box is attached to the case. Grime collects there, anyway.

Sometimes I wonder if my thrifty reuse (over and over) of the nylock nuts might allow oil which somehow got on the stud to escape, where with new nuts nothing would have gotten past.

The copper crush washers on the cam carrier oil line banjo can be overtightened or otherwise distorted. Since that oil is under pressure, it can find a way out.

The pressed-in pins which hold chain guides and the tensioner can loosen a bit, which is why where they come out the rear (front?) of the chain box they get a cleaning and slathering of epoxy each rebuild, at least if they show signs of cracking.
Old 10-19-2010, 05:28 PM
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