First you need to determine exactly where the leakage is coming from by
close examination of the back of the engine and the flywheel. is the leakage
out of the seal itself onto the flywheel and then covering the front face of
the flywheel? Is the leakage from the sides of the main cap where it meets
the block?
For years we have used "silicone sealer" along with the felt packing on
the sides of the main cap. We cut the packing into pieces about 3/8" long.
During the packing process we look for the sealer to come out in a solid
line beginning at the very bottom corner (as the block is upside down) and
continuing all the way up to the pan gasket surface. Then we wipe off the
excess.
As for the seal itself. I would get a round piece of stock the same size
as the seal surface on your crank. Fit the seal around that surface with the
spring in place on the seal. hold the seal in one hand and look at the way
it fits against the metal surface. Is the sealing lip deflected (it should
be), you should be able to move the seal radially from side to side up to
almost 1/8" and not see light anywhere around the seal lip where it fits
against the "dummy crank".
Lastly, it is imperative that the aluminum seal holder halves fit
tightly against one another while at the same time not holding the rear main
cap up from seating firmly against the block! We have seen this situation
where the cap will not seat all the way down against the block because the
seal holder is mismachined and when it is bolted to the block and cap, the
holder faces touch before the cap will touch the block. The center of the
seal holder must also be nearly perfectly centered on the crankshaft. You
must use a centering tool of some kind to make sure this is so.
If you get all of this right, the seal should only leak a tiny bit. We
have never been able to make this type of seal completely dry as we have our
Chrysler seal conversion. But without building the size of the crank back up
you are stuck with the seal you are tying to use.
Greg Solow