[68WarDog]

I do have a known oil leak at the fuel pump block-off. I believe I need to seal the threads on that. I've not been able to see that leak flowing rearward to the back of the engine however.

I had this problem after installing the EFI. block off plate wasn't properly sealed. And I was surprised by the amount of oil leaking from that area. Not Folger can size, but definitely 4" diameter on the garage floor, not to mention the amount spread by the wp fan.

[67Fbird]

Originally Posted by 78w72

what year oil pan? if its the older ones with the 3 holes in the rear U section they are known to leak there due to the rubber U seal, it can roll or get squished out of place & cause a leak that will look like a rear main leak. inspect that area real good after wiping it dry with a good solvent or brake cleaner. it could be leaking anywhere in the U area & where the ends meet the side rail gaskets.

^^^^ yup exactly what I just fixed on my new motor after checking out the flywheel was oily on the back side??? sure enough he rubber squished out under the crank......just a little bit.. BUT the only reason I used a regular gasket was my 1 pc butler had nod made it to the house YET when I put it together.

[JLMounce]

Originally Posted by PDC

Sounds like you have tracked this down to the back of the oil pan. But just for whatever its worth:

I had these fabbed valve covers on both of my E-Headed cars with the thin, steel reinforced Viton VC gaskets. They look fantastic. But, at least on my cars, the bolts that drop through the holes in the valve covers were just barely bottoming out in the holes in the heads before getting a decent compression on that Viton gasket. It all ‘felt’ snug - but they leaked like crazy - especially at the rear of the head by the firewall. My starter was coated with oil. I ended up using a band saw to carefully lop the last 1-1/2 threads off the bolts then cleaned them with a die. That gave me just enough clearance to compress the Viton gaskets. All was good after that.

Originally Posted by mgarblik

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!

Thank you both, this is great information.

Fortunately when I did the valley pan last spring I followed exactly the step outlined. Cork gasket with a thin film of (in my case) aviation gaskaseal. That has been leak free.

I'm finishing up a brake project this weekend and will get the car back on my lift. I'm going to try and clean everything up nicely and get some right stuff in there. If I can even just reduce the drip, that would be great.