[Fot] Rear Main “Rope Seal”update

[Phil Gott]

A while back many of you were kind enough to share your methods of sealing the felt or rope seal area of the rear main.
We have tried 2 of them should o far with mixed results and have arrived upon a third method I think is best.
Using Kas’s method with Aviation Cement has been our tried and true approach. However, the oil we are using, Driven XP, turns out to be a solvent for all but the most hardened of the Aviation Cement. And leaks develop over time.
We then tried diluting Hondabond HT with acetone and “marinate” the felt in it. Using the Kas method, as in the shop manual, successfully packed the trapezoidal volume, and the Hondabond oozed out the sides. The acetone did not significantly thin the Hondabond, and penetration into the felt was very limited. Nonetheless, we think this will hold up, but worry a bit about the Hondabond not drying in the center of the Trapezoid, as contact with air (Moisture) is needed. It made a bloody mess as well.
So we looked further. Permatex has an Anaerobic version of rtv. Expensive at about $15 for a small tube, but we tried it. Cut off the usual tapered plastic nozzle to just fit into the trapezoid, fitted a 5/16 washer over the end to seal the trapezoid (see picture), and squeezed the tube to fill the hollow trapezoidal volume until the rtv came out the chamfered hole at the cap and block mating surface. The washer made a good seal, preventing the rtv from coming back out the end of the hole. For comparison, I did the same thing on the other side with regular rtv (Blue just because it was handy).
After 5 days I removed the main cap from the block and found that the anaerobic rtv had fully cured, but the regular, air-drying (really moisture activated) rtv to be still very much in putty form, just as squeezed from the tube. See pictures. Note the anaerobic rtv oozed into the space between the side of the cap and block much better than the blue regular rtv. I did not prep the block or cap with the recommended activator for the anaerobic rtv, which is said to improve the bond. 
Will be using the Anaerobic in this area from now on, once I test it for resistance to Driven XP.
Thought this might be helpful.
(Yes, it is a rusty and cracked old block used for experiments, having donated its body for science....)
Phil Gott
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