The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Anybody ever have a 350 that doesn't leak?

**LEEVON** · 05-16-2013, 06:35 PM

I won't have leakers in my driveway. That said, it's not easy to get there! The thick blue rubber felpro gasket for the oil pan, when installed correctly does not leak. Don't use the valley gaskets on the ends of the manifold, but RTV instead. For the valve covers, here is the deal:

1. 5/16" cork gaskets. Yes cork, not rubber there is a reason!
2. Make sure your valve covers are flat and true. Chrome sucks, don't use it!
3. Apply a liberal amount of the "right stuff" gasket maker to the valve cover.
4. Place the cork on the valve cover.
5. Set the whole thing down on the flattest surface you can find. I'm talking mirror flat. Set some weight on top of the valve covers while the right stuff cures.

The surface that mates to the head will now be as flat as the surface you put it on. They key here is FLAT-TO-FLAT!!! Any imperfections were taken up in the cork material and the sealant. The sealer will "squish" just enough at humps or "fill" at bellies. Use load spreaders, and just snug the bolts. Not tight!

Worst oil leak I ever chased was on an '87 TBI 305. It looked like the rear main, but wouldn't leak at idle where I could see but only after it was good and hot and at higher speed (thus coating the whole underside of the truck). Clean, drive, inspect, clean, drive, inspect, clean, drive, inspect. Replaced the rear main seal and oil pan gasket. Still leaked. Went ahead and did the timing cover, intake and valve cover gaskets along with the distributor JUST TO BE SURE. Still leaked. Looked like the rear main, maybe I didn't get it perfect? PULLED THE WHOLE ENGINE! Went over everything again. Still leaked. I was about to burn the thing down. Then for some reason I thought to remove each of the bellhousing bolts and inspect them. Sure enough one was about 1/4" longer than the rest. I shined a light in the hole and couldn't see the bottom. Turns out it had busted into an oil galley. One tiny squirt of sealant on the bolt fixed the whole dang thing. When I sold it, I told the guy how hard I had worked and he says "It don't matter to me, I park on gravel and dirt all the time". DANGIT MAN, give me some credit here!!!

05-16-2013, 06:35 PM	#16
LEEVON Registered User Join Date: Jul 2006 Location: Ozark, MO Posts: 4,887	Re: Anybody ever have a 350 that doesn't leak? I won't have leakers in my driveway. That said, it's not easy to get there! The thick blue rubber felpro gasket for the oil pan, when installed correctly does not leak. Don't use the valley gaskets on the ends of the manifold, but RTV instead. For the valve covers, here is the deal: 1. 5/16" cork gaskets. Yes cork, not rubber there is a reason! 2. Make sure your valve covers are flat and true. Chrome sucks, don't use it! 3. Apply a liberal amount of the "right stuff" gasket maker to the valve cover. 4. Place the cork on the valve cover. 5. Set the whole thing down on the flattest surface you can find. I'm talking mirror flat. Set some weight on top of the valve covers while the right stuff cures. The surface that mates to the head will now be as flat as the surface you put it on. They key here is FLAT-TO-FLAT!!! Any imperfections were taken up in the cork material and the sealant. The sealer will "squish" just enough at humps or "fill" at bellies. Use load spreaders, and just snug the bolts. Not tight! Worst oil leak I ever chased was on an '87 TBI 305. It looked like the rear main, but wouldn't leak at idle where I could see but only after it was good and hot and at higher speed (thus coating the whole underside of the truck). Clean, drive, inspect, clean, drive, inspect, clean, drive, inspect. Replaced the rear main seal and oil pan gasket. Still leaked. Went ahead and did the timing cover, intake and valve cover gaskets along with the distributor JUST TO BE SURE. Still leaked. Looked like the rear main, maybe I didn't get it perfect? PULLED THE WHOLE ENGINE! Went over everything again. Still leaked. I was about to burn the thing down. Then for some reason I thought to remove each of the bellhousing bolts and inspect them. Sure enough one was about 1/4" longer than the rest. I shined a light in the hole and couldn't see the bottom. Turns out it had busted into an oil galley. One tiny squirt of sealant on the bolt fixed the whole dang thing. When I sold it, I told the guy how hard I had worked and he says "It don't matter to me, I park on gravel and dirt all the time". DANGIT MAN, give me some credit here!!! __________________ '20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids Last edited by LEEVON; 05-16-2013 at 06:41 PM.