| |
Click on image for the lowdown. 
====
| | | Forums66 Topics128,022 Posts1,055,381 Members48,422 | | Most Online14,466
Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
Lots of work on Brad's part ... pure enjoyment (and references) for you!
| | THANKS!
For helping keep this great
old truck web site
on the Internet for over 30 years! and not clogged down
with Ads!  Again, thanks!
| | | | Joined: Mar 2008 Posts: 31 New Guy | | New Guy Joined: Mar 2008 Posts: 31 | Rebuilt my 270 and now the rear main seal is leaking. Any ideas why this could be leaking after rebuilding. Used a good seal from Fel-Pro.
I thought it would swell up and stop, but after I stop theres a good spot on the ground.
Anyone heard of a rubber seal? If so, can I use one for this and where can I find one?
Thanks | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Many of the rear seals sold for GMC engines tend to leak. Check out the oldGMCtrucks.com discussion board. A good rear main seal has been identified and discussed on that site. | | | | | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | This is one of the things that I spent some time on this summer. Although my motor is a 216, I think the problem is similar.
When I rebuilt my 216, I did it in place because I didn't have a choice. As part of the rebuild I installed a new rear main seal. I didn't replace the main bearings. The seal lasted for a few hours and then began to leak. This summer I replaced it with the Best Gasket product which is teflon based. That seal lasted for about 100 miles. On my next try I replaced the main bearings. As it turns out they had way too much clearance. On the 216, shims are used and I was able to adjust each main for the minimum clearance. I installed an NOS rear main seal and it has held up really nicely.
My point here is the problem was excess clearance in my main bearings allowing the crank to move around. I also think that the Best gasket product is a superior product. | | | | | Joined: Feb 2004 Posts: 29,746 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,746 | Ding- - - -Ding- - - - -Ding! "Give the man a seegar!" You've discovered what a lot of oldtimers used to know instinctively. No seal can keep up with a shaft that's bouncing around in a loose bearing well enough to prevent some seepage past the seal. That also holds true for rubber lip seals, not just the old style rope ones. Back when I was doing a lot of automatic transmissiomn work, I would not change a torque converter seal unless the car owner would also agree to changing the bushing in the oil pump that supported the converter. Driveshaft yoke seals weren't quite so bad about failing from a sloppy fit, but it was also a good idea to change that bushing when installing a new slip yoke seal.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Mar 2008 Posts: 31 New Guy | | New Guy Joined: Mar 2008 Posts: 31 | Thanks, I found a lot of info on oldgmctrucks.com | | |
|
|
| |
