3.6 Post Rebuild Oil Leak Question
 

Hi,
I just finished rebuilding my 90 C2 3.6, and it's running great. Unfortunately at the end of the 15 minute high idle warm up, there was a puddle about 18" diameter under the left (1-3) cam box. I followed the oil, and figured it was paper gasket between the cam carrier and the chain housing. I pulled the muffler, rear heat exchanger pipe, and the plastic sound cover to get a closer look. There is oil dripping from the bottom of the chain box, and the bottom of the valve cover (rear), but the cam carrier below where the paper gasket would be seems dry..... I wiped with a paper towel, and there isn't any residue......... The spark plug wires are dripping also. I've sprayed it down with brake cleaner, so it's dry, and tomorrow i'll run it and see if I can find it, but figured i'd ask about other points of leakage around here. It's a pretty fast drip, so I think it has to be under some pressure.

Thanks for any ideas.

-Eric
90 C2
NER/PCA

Rocker shafts?

Will it be obvious if I pull the valve covers off?

-Eric
90 C2
NER/PCA

I think the ends of the rocker shafts need to be dry when or if you inspect them. Since you've got the engine cleaned up, I'd probably start it and watch it closely before I began removing things. See if you can actually find and watch the oil leaking out. It could be as simple as a tensioner oil line that's loose.

You might have enough room to feel the rocker shaft ends through the valve cover spark plug holes.

On the 3.6 there are no oil lines.... I checked the cross over "bridge", and the ends are dry...... top valve cover is dry, but the bottom valve cover is wet..... rocker leak can't be worse than resealing and retiming the cam....... maybe...........

Thanks,
-Eric

Turns out to be the paper gasket between the cam carrier and the chain housing after all. It dribbles along the cam housing before spraying everywhere.......

-Eric
90 C2

thin coating of 574 on paper gaskets would probably help.

Kirk

Per the factory manual, I did put a thin coating of 574 on. But on removal, the gasket was oil soaked on both sides, so it didn't seal correctly for some reason....... The other side of the engine is dry, so I'll try it again. It was recommended by a parts vendor to put the gasket on dry, but I'm planning on using the 574.

Thanks,
-Eric
90 C2

Eric, I had this problem with my 3.2 SS rebuild my mechanic found that the cover plate wasn't flat and machined it to correct the problem. 2years now and no leak.

It was recommended to me that on the thin paper gaskets to use Permatex copper spray-a-gasket sealant. Spray them both sides let it dry, spray again and install while tacky. (5300 miles on rebuild now and no leaks)

The magnesium chain housings need some "special" attention during the rebuild process. You need to scrape all mating surfaces with a sharp straight knife blade. The magnesium ususally has pit corrosion to the point where your standard gaskets (O-ring, paper gasket) simply are not longer able to seal properly.

Use a carpet knife blade at 90 degrees (perpendicular to the surface) and scrape until you see a uniform shiny silvery finish. Do not cut but scrape. At the sealing surface where the O-ring goes (the cam shaft hole) it is a little more difficult. I did this to two engines and they are both dry.

Ingo