The Stovebolt Site Forums The Shop Area Engine Shop Rear main seal replacement

Geez,
While I'm at it why not add another detour to my project. Yesterday while working near the tranny I do see engine oil on the clutch cover as well as the rear outer portion of the pan. I looked at Oly's "blonde proof" tech tip instruction and it doesn't seem that difficult except a blonde might ask while reading his neoprene section if you still need to loosen the other caps to allow the crank to drop a tad like in his wick type seal section.

http://www.stovebolt.com/techtips/rearseal.htm

Also viewed previous comments in the archieves with most people saying to go with neoprene replacement seals anyway.

Any other comments, suggestions or tips?

I thought if your engine takes the rope type seal, a neoprene seal would not fit. If I am wrong someone tell me!

Does anyone know what year did they switch from rope to neoprene for the 235 ?

don't know about the 235, but I know that the rope seal 283 blocks won't take the neoprene seal

Bill

235's never came with anything but a rope seal. There is a neoprene replacement that will work on 1955-62 engines. The main reason the neoprene seal will not work on the earlier engines is because they used shims on the mains and the ends of the seal can not butt flush with shims.

You can have the grooves machined to except the neoprme seal, which are much better. The rope type seals seap.

I thought it was supposed to leak and drip off that nipple you found?
:p

Pre'68 Dave is correct. In fact, it is quite possible that the rear mainseal may not be leaking, but that the oil is escaping where the rear main cap is spaced slightly because of the shims. If so, the oil will leak out through that space. Not much you can do about that, but it would be worth taking a look at.
If you replace the seal, rope is the only way to go on your engine.

My engine is a '62 235. So this means I can use a neoprene replacement?

Good mornin' Tony M. Last night I knelt by my bedside asking the almighty rain gods or goddesses to take a hike between 1-3 today. Watch them laugh and snub my request....

cmayna, The neoprene seal is fine in a 62 engine. You should always check the crank sealing diameter for pitting and to make sure it has not been turned down, that would be the only thing stoping you. Stock Dia. 3.875".

:rolleyes:
Craig, I didn't realize you had a 62 engine in your truck - I thought you were running an early 235. Some of my comments may not be applicable except that I still think a rope seal is best. But, that is my opinion!

The older NOS rope seals work better than the fel-pro replacements. The NOS seals had asbestos in them, which seals better than whatever is used now.

I did use a neoprene seal in my old '54 235, and it didnt leak any more than normal. :rolleyes: The seal ends did butt together OK in my case. I've come to expect that if a 235 isn't leaking oil, its low on oil.....

The rope seal is by far superior to the neoprene. Just because it is "old school" doesn't mean it is "bad school".

Ralphy, The reason you leave 1/64 inch on the upper rope seal is so it will suck into place when you bring the crank up tight. the lower seal needs to be pressed into place (but not an undo amount of pressure- let the crank do that or it will surely leak again)

So whats the verdict, on a '54 235 can you use neopreme? I had my enging rebuilt but has been leaking, I am in the process now of replacing the front axle with new king pins. Should I replace the rear seal with the rope while the axle is out???? :confused: :confused:

rat,
I'll be in the same situation as you very soon while I'm replacing my entire front axle assy. No matter what, I will drop and clean out the sludge in the pan and replace it's gasket.
Also no one has yet to answer part of my original question which was if replacing neoprene seal if you still need to loosen the other caps to allow the crank to drop a tad like you would when replacing the rope type seal.

To Rat, as I mentioned earlier on an engine using shims the shim extends about half way on to the parting line of seal preventing the seal ends from butt completly together. If you cut the shim back so the seals can butt the oil can go arould the back of the seal there the shim should be. It is a little hard to explain, but if you study it you will see what I meen. Also the seal groove in the block is deeper on the pre 55 engines so the neoprene seal will not have the correct presure aginst the crank.

cmayna, if your engine has a rope seal now you will need to drop the crank some only to get the old seal out, the neoprene seals when oiled will slip in and out easily.

I've installed both the rope style and rubber lip seal, both work equally well if done carefully.Yes, get a NOS rope , works better than the rubber seal if the crank area where the seal rides is worn or pitted.The rear seals in my trucks don't leak more than a drop now and then and it's maybe just the oily mess underneath created by the road draft tube.
It's always best to install the rope seal with the crankshaft removed like some mentioned above by Ralphy.But a satisfactory repair( leaks not too bad,lol.) can be accomplished by just drooping the crank slightly, which requires tranny removal.

:mad:
Craig - Get a rope!

"Should I replace the rear seal with the rope while the axle is out????"

YES!!! by all means do!

So much for being "Blonde Proof"-LOL

"Also no one has yet to answer part of my original question which was if replacing neoprene seal if you still need to loosen the other caps to allow the crank to drop a tad like you would when replacing the rope type seal."

Yes!!! It makes things go a lot easier and you can get a "sure" fit when it goes back together.

The rope seal is by far the best bet. Don't use a jack to push it into place. You could push it to tight and then it will leak for sure.You want to let the crank push the upper seal into place for the seal to fit perfectly. If you have an old reground crank (don't we all?) then there will be some amount of wear on the crank (from grim) where the seal goes. The neoprene seals are made only to one size and can't swell up like the rope seals to fill the gap.

I know, from experience, that this can be a miserable task at best, but if done properly you shouldn't need to do it for another decade or so.

Iput an 54 235 in my 51.I ordered a gasket set from napa and it came with a neoprene seal.I installed it and its worked fine for me.

This is what the guys who built the truck have to say about the rear seal
[img]http://img.villagephotos.com/p/2003-1/95040/HITYR-rearseal.jpg[/img]