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

'53 235 w Powerglide. The rear main is leaking. Is it possible to replace without pulling the engine?

It would be difficult, since the torque converter and the transmission input shaft will hold the back end of the crankshaft up tight against the seal. There's enough slop in a manual transmission input shaft to let the crank be lowered a few thousandths without disassembly. If you're dealing with a rope seal, I'd guess no. Changing a lip seal without disconnecting the trans from the engine MIGHT be possible, but difficult.
Jerry

Tiny this may or may not work for you, but might be worth a try before pulling out the engine. I did this around 20 years ago on a 1956 Cadillac with auto trans. It reduced the drip notably but didn't stop it completely. I was later told the remaining leak was probably from a seeping head gasket. As I recall, those gaskets are known to leak back at the rear area of the valley pan and pour down the back side of the block imitating a rear seal leak.

The technique is this: Remove from a windshield wiper blade the stainless spring steel piece--there might be 2 in each blade. It is apx 1/8 inch wide and maybe 20 thousands thick or so...could be 15 thousands. Measure it in the lower bearing recess seal slot and cut it, grinding one end tapered. Round that sharp edge a bit so it resembles a dull knife. You don't want it to try to cut into your rope seal but you do want a taper on the top of the end going in first. With a small hammer drive it carefully and slowly between the back side of the upper rope seal and the recess in the block until the ends are flush at each side. If it works like it did for me, the piece will follow along the channel. Replace the bottom seal in the normal way and put gasket sealer over both the bearing cap ends and the exposed rope seal but not all the way to the crank edge of that seal. You're just compressing the existing seal on top closer to the crank surface. When I did this, the crank wouldn't drop much at all (as Jerry said).

Good luck!
Jon

The tool used to replace the rear main seal is called Sneaky Pete.

Amazon has it: https://www.amazon.com/Lisle-27000-Sneaky-Pete-Tool/dp/B0002SRCJW

I've used ole sneaky pete a few times. Still have it laying in my tool box for the next one!
On one or two occasions I have loosened the main bearings to take a little pressure off the rear seal but Jerry makes a good point.

Thanks gentlemen.

If it's possible to unbolt the torque converter from the flex plate, the crankshaft could probably be lowered far enough to free up the upper seal and allow it to be swapped out.
Jerry