Tom Austin

I had my 66 L79 rebuilt 3 years ago and have been dealing with an oil pan leak issue ever since. The leak is at the front of the pan. It turns out that my engine builder used a common replacement oil pan (with the 2 3/8 front lip) - which requires a "thick seal" oil pan gasket. I've tried the Fel Pro one-piece gasket (part # OS-34510T) - and it still leaks. I'm thinking of trying another one-piece gasket - either the Fel Pro Performance gasket (part # Z1880) - or the one from Mr. Gasket (part # 6560). Anybody have an opinion on either of these options??? Thanks guys!!!

Tom

54greg

Same problem here

PinkVetteLady

I have used the OS-34510T on my car and used one this weekend on another motor. The trick is that you have to put a small bead on the inside and the outside of the front and back of the gasket. That will help prevent a leak at the timing cover and below the rear main...

L78racer

I have used the Mr Gasket 6560 with good results. Plus being black it's easier on the eyes than that blue one...

salty_waders

I was fighting this same problem. I used a Milodon one piece gasket (part number 697-41000 from Jegs) and Permatex Ultra Grey gasket maker and had excellent success. Make sure you try the Permatex Ultra Grey, that stuff works great.

midyearvette

.....the ultra gray is great stuff, just be patient and let it cure overnight

Shurshot

When using the one piece gaskets from Fel Pro the performance one calls for adhesive while the normal duty one does not.

Use the performance one and put a bead all the way around

Doug

Lee H

I have had the same problem. I went through half a dozen gaskets trying to seal the leaks. Turns out it was not a gasket issue, it was the common replacement oil pan. These pans are for the most part junk. I replaced the pan with a real GM pan and no more leaks. I know they are expensive but not as expensive as dealing with oil leaks and replacing gaskets several times.

muncieman

Knock off Chinese crap

DZAUTO

All of the above is good info!

I LOVE the one-piece pan gaskets! Although (from personal experience), I ALWAYS use a bead of quality RTV on the TOP and BOTTOM of the front and rear of of the one-piece gaskets-------------------------and a little extra in the corners. Even though the gasket installation instructions say no sealant is needed -----------------use some anyway!!!!!!!!!!!!!! Not an excessive amount, just enough to make a good seal.
I can't speak for aftermarket/off shore pans--------------------I ONLY use genuine Chevy pans (and Oldsmobile pans on the 455 in the Cutlass).

Tom Parsons

JohnZ

The same goes for timing covers - the China/Taiwan/etc. ones, especially chrome, usually have the lower flange mislocated, and spot-welded instead of continuously roller-welded like the GM originals, so they leak. Non-GM timing covers are a crapshoot.