General post concerning Pontiac oil leaks. Little background. I was in charge of repairing ALL the oil leaks at my Pontiac dealership when I worked there. actually all leaks period including water leaks and wind noise. The #1 Pontiac oil leak is the rear main seal. (at least it was when rope seals were all I worked with). #2 was the rear of the oil pan #3 was valve covers. Both the oil pan and valve covers had the same problem. Thin, crappy sheet metal parts and not enough fasteners, and spaced too far apart. #4 was the valley cover. (again, huge thin, cheap piece of sheet metal, 2 fasteners, #5 Timing case to block and front pan. I replaced 13 rear main seals in Pontiac V-8's in one week at the dealer. Took 2-2.5 hours in the car once you had all your proper wood blocks for each body style. Moving on: Oil plugs, freeze plugs, cam plugs, casting porosity, pretty rare leak sources. Occasional fuel pump pad and oil filter pad leaks.
My best fix methods and procedures/products. Rear main seal: Rope: the "Best" brand seal, packed hard into the groove and cut with a NEW razor only, Dot of RTV on seal ends. Rubber seal: BOP 2 piece or 1 piece seal following their instructions and lube the lip. MUST have a second person to install the 1 piece seal. Rear of pan: cork seal if cap has a groove, I do not use the 3 or 5 tab rubber seal. That is a leak source. If cork, a light film of RTV on pan side of the cork and small blob in corners. If no cork, thick bead of RTV only. Valve covers: I do not use any type of rubber gaskets. Cork only, glued to cover lightly with a tack agent, like high tack or weather strip adhesive, nothing on cylinder head side. Do not over tighten. Valley cover: Preferred method Cork gasket. I test fit cover first, no gasket, adjust with shot filled hammer as needed to get consistent gap. Then lightly tack cork to cover with high tack or weatherstrip adhesive. Then I apply a light film of RTV to the cork, cylinder head side and install. I put a small amount of RTV around the bolt heads at the top where they contact the valley cover. Timing case to block: I use the paper gasket and aviation form a gasket liquid on the paper gaskets for timing case, water pump and thermostat housing, very thin coat. If case is badly eroded, sometimes use a small amount of RTV to fill. Use a small blob of RTV at front corners. I hope all this makes sense and helps.
I love Pontiacs, but they are very difficult engines to seal, because of a number of compromises in the design. The #1 fault is too much space between fasteners IMO. Then when over tightened, it just makes a bad situation worse. Much like owning a Harley, I guess, we have to live with a little drip sometimes. I have mentioned using a smoke machine to find a specific leak point is by far the best way to pinpoint a leak. IMO, much better than dye. Good luck with your repair and I hope this long post has a few ideas some can use. STAY DRY!
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