The Stovebolt Site Forums The Shop Area Engine Shop Rear Main Seal on 235 Engine

Has anyone ever replaced the rear main seal in a 235 engine while still in the truck using the Sneaky Pete Seal Too? If so, did you use a rope or rubber gasket? How hard a job is it? Thanks!

What is the year of your 235?

Best Gasket Ream Main Seal - part number 6100 - "rope"
https://www.ebay.com/itm/Chevy-GMC-...ng-Seal-Set-BEST-1940-1963-/191555289615

A Sneaky Pete will help remove/install a rope seal.

You might have a rubber seal?

Engine year is 1959. It seems to me a Sneaky Pete would work better with a rope seal.

The Sneaky Pete, as posted above, it made to work with a rope seal.

I think you can use a rope seal in a later 235/261 that came with a rubber seal. Maybe someone will confirm/correct?

You can replace the rubber seal with a rope seal, Tim. If you have the rubber seal currently, those do wear out and will leak when they do. You normally don't need a Sneaky Pete or anything to replace them. Normally you can push the end with a small screwdriver and turn the crank and have them follow out. If you're curious, here is one which came out of a 1959 235 compared side to side with a new rubber one. I think you'll see why the old one was leaking:
http://i1154.photobucket.com/albums/p535/JonGoodman/rearmainendtoend.jpg

This may or may not work for you, but it is a different approach and might be worth a try if you have a rope seal. I did this around 20 years ago on a 1956 Cadillac and while it did reduce the drip it didn't eliminate it. I was years later told the remaining leak was probably from a seeping head gasket. From what I recall, these gaskets leak predictably at the rear of the valley pan and mimic a rear main seal.

I watched a fellow fix a rear main leak in place using a stainless spring steel piece from a windshield wiper blade. It was about 1/8 inch wide and maybe 25 thousands thick. He measured it in the lower bearing recess and cut it, grinding one end tapered and then rounded that sharp edge a bit. Then he slowly drove this between the back side of the upper rope seal and the recess in the block until the ends were flush on both sides. He replaced the lower rope seal in the normal way, put gasket sealer on (the seal piece ends also) and tightened everything back up again. It is all a matter of trying to push the rope seal closer to the crank surface.

Good luck!
Jon

One strange thing I will add. About 4 or 5 years ago when I removed the crank from a 235 (1957 or 1958 year) I noticed something odd. Somebody had drilled holes and set what looked like little nails which had been pounded flat at the tip in the bottom of the seal channels. You can see three of them in the cap in this image (compared to a normal cap above it). There were as I recall 6 in each channel and they stood above the surface about 1/16 inch or so. You can see they're staggered as if somebody did this with a drill press but "freehand" in style. I assume these were added to keep the rope seal from moving, but what a bunch of work and I've never seen this on another one. I remember thinking it would have made removing the seal with a Sneaky Pete more difficult. This engine had been rebuilt before I got it. As I recall the pistons were 20 over and the crank was 10 over.

http://i1154.photobucket.com/albums/p535/JonGoodman/closerinspection.jpg
http://i1154.photobucket.com/albums/p535/JonGoodman/continuesacross.jpg

Jon

Guess I'm getting old ? I cannot see them ?

See if this helps:
http://i1154.photobucket.com/albums/p535/JonGoodman/continues%20across2.png
http://i1154.photobucket.com/albums/p535/JonGoodman/closer%20inspection2.png

I did not see at first, either, old55guy - I had to monkey with the ZOOM of the browser.
Then I saw perfectly.