Changing a rear main seal on a 1950 straight 8-70 series

[Guest BCA42496]

I am sure this has been posted before but I can not find anything. I have changed the rear main seal once and it still is leaking. I used a "Best Gasket" product, is there a better product available? Are there any installation tips that you can give me with my next try? Thank you, Kirk

[old-tank]

How to stop rear main seal leaks

I have worked with early 322 nailheads and one 47 straight-8, so yours should be similar. Some of this can also apply to other engines with rope seals.

Some assumptions: You know how to get to the rear main bearing cap and remove it and you know what a rope seal is. The engine is in the car and the crankshaft is installed.

Do not remove the upper seal. If it is not now absolutely flush take a portion of the used lower seal and stuff in the gap with a suitable tool. It is ok if it protrudes some. Take a 12 inch length of heater control wire, sharpen one end and install it into the groove that the upper seals sits in using a 6 inch length of brake line to keep it from kinking. Using vise grips push 1/4 inches at a time until it shows up on the other side. Install 2 pieces. Cut the wires flush with the block.

For the lower seal that goes in the cap take the piece that is supplied for that engine, bunch it together and flatten it and place it in the groove in the cap. Bunch it some more to make it fit while pressing it into the cap with a piece of exhaust pipe about the same diameter as the the crankshaft journal. Never cut or trim a seal to make it fit. It is OK and desirable if some seal protudes from the cap. (For situations where the crankshaft is out of the engine, remove this seal from the groove in the cap and place it in the groove in the block; repeat for the lower seal.) Fold any stray strands of the seal to the center so they will not get caught between the

clamping surfaces. Install the cap and torque to specs. Remove the cap and trim any stray strands that got clamped. Put some gasket sealer on the clamping surface of the cap. I use an anaerobic sealer. Dribble some engine oil on the seal only until it is saturated. Install and torque to specs.

To seal the groove in the sides of the cap I take some cotton twine coated with some No. 2 Permatex and hammer it to stuff it tightly in the groove using a large flattened nail until it is level with the top and cut.

Willie