The Stovebolt Site Forums The Shop Area Engine Shop 261 Rear Main Seal Replacement

How easy, or difficult is it to replace the rear main seal on a 261 without removing the crank? A friend of mine said it will probably have a rope material seal that can be removed by carefully screwing in a wood screw into the material, careful not to scratch the crank, turn the crank and pull on the screw at the same time. And that a modern rubber seal will slip right in. Has anyone ever tried this or similar methods?

I have 1959 261 and have the rubber seal on it. I replaced it when the engine was rebuilt.

I got a good tip on this site: When you put the neoprene seal in rotate it just a bit so the ends don't line up with the bearing cap. That helps keep the seal effective cause the greatest path way out is blocked. Not too hard and it has worked for my 235 which was leaking bad. Now it is dry as could be for the last 600 plus miles.

If there is a rope seal in it, it could be tough to get out. I have put a neoprene seal in a 194 (230 250 family) with the crankshaft in place with no problems. The first one I ruined because I let the back of the seal rub on the edge of the block and it carved a hunk out of it. On the next try I kept it compressed a little as it passed the edge of the block.

Just an update. I had no problems removing the old rope seal. Whoever installed it left one side a little long, which is recommended by Fel-Pro. I simply grabbed it with a pair of needle nose pliers and out it came. I was equally successful in installing the new Neoprene seal. won't know for a couple of weeks if it worked though. Wish me luck.

That is how I have done a bunch-you ought to be just fine, Well done!

Reviving this old thread to ask a question:

It has been so long since I rebuilt my 261- can you get the rear main cap off and replace the seal without pulling the flywheel?

Yes, it will come off with the flywheel in place. If you drop the crankshaft, please remember to also remove your harmonic balancer. It will give you some room for the crank to go down without damaging the timing cover seal.

Thanks Jon….I’m not going to drop the crank- it’s just my rear seal is leaking, so just a seal replacement. I was so careful installing the first one (engine has about 100 miles on it now), any tips on getting it to seal better this time? I’m pretty sure I installed a neoprene seal in it.

Dave, we've been discussing this on another post with a gentleman who is currently rebuilding his 235. With the neoprene seal (or the rope seal either) it is important for your crank surface (the part riding against the seal) to be as smooth as possible. If yours is that way, then it tells me your seal may not be making good contact with the crank surface. About the only way I've found to solve that is to cut some shim pieces from self-adhesive foil (the kind the HVAC folks use) to pull it closer to the crank a bit. When you remove your old seal you might want to compare it end to end with a new one. That way you'll know if your crank is too rough. If so it will wear the seal down just like rubbing sandpaper on it. Good luck!

How bad is it leaking, Norcal? If it's just a small amount, I'd call it normal and forget about it.

Thanks Jon!

Otto, It is more than a seep- it is dripping out while driving and then making about a 5 - 6 inch wide flat spot on my floor after a drive. I’m concerned it might end up contaminating my clutch disc over time.