The Stovebolt Site Forums The Shop Area Engine Shop How to ID a nos rope rear main seal for a 216

Long title but that's my question. Now the why for my question. My truck had a documented 43,000 miles when purchased back in '13. It's now at 59k miles. In the past very few years and less than 10,000 miles I've installed two Best Gasket rear main rope seals. The last was in February '23. Now 5,000 miles later the rear main is leaking to the point clutch chatter has made the truck almost undriveable at least on the initial start. Taking off in second or third with a lot of slipping the clutch helps.

On the last seal replacement I adjusted the main clearances to the book minimums, torqued by the book and installed the rope seal using all the expert guidance I could find. The sealing area of the crank looks new. I "thought" I'd licked the oil leak beast. Nope!

So now I'm toying with pulling the rear main cap and trying to use a hardwood dowel to drive the top rope in and add a bit of rope along with a dab of sealer to tighten the seal. I've read of such techniques being used in the past.

The other more likely route "If" I can find a original NOS rope seal is to ditch the Best Gasket seal and go with the NOS asbestos seal. I've found a few NOS seals, but don't know how to tell if they're what I want. Would a NOS seal from the 50's or 60's be white or have any other visual hints it's actually what I'm looking for?

Thanks in advance.

RonR

There's a much better way to tighten a rope seal, using a thin stainless steel strip cut from a discarded windshield wiper blade. Loosen all the main bearing caps about 2 turns, and gently tap the strip behind the upper seal rope to shim it tighter against the crank. Then S-L-O-W-L-Y tighten up the rear main cap while moving the flywheel back and forth to reshape the seal surface against the crankshaft.

Or- - - - - -do it the right way and machine the block for a full circle lip seal.
Jerry

So the wiper blade piece stays in the engine?

Yep, it's just a thin shim that fits between the back of the upper rope seal and the block. Then the main bearing cap is tightened in small increments as the rope forms itself to the crankshaft contour.
Jerry

Jerry, I like that simple fix. Another project is begging for a little love (on the lift for 4 years). Once that problem is worked, it’s back to the’51.

RonR