Originally Posted by boyt911sc (Post 11013157)

BC,

I mentioned this subject to Pat O’Keefe’s attention when was trying to solve the oil leak coming out from the nose bearing. The key to fixing this annoying oil leak aside from opening the crankcase is to find and use the correct sealant that would adhere strongly to the aluminum surface.

The aluminum collar and the nitrile rubber plus sealant would be more complex because you have now more materials to consider. A sealant that will adhere strongly to both aluminum and nitrile. Unlike in the previous scenario, only aluminum surfaces. Have you checked with those people that have done it successfully what sealant were used?

Or try Henry’s product. The key to your success is not the mechanical approach only but heavily dependent on the sealant’s properties. Good luck.

Tony

Originally Posted by burgermeister (Post 11012374)

Originally Posted by burgermeister (Post 11012372)

While I have had a cornucopia of engine problems and oil leaks, I have not (yet) had a nose bearing leak. So I have not fixed one.

With an O-ring compressed into the case front and nose bearing outer, the clamp ring should never see any oil (assuming this strategy works) - so the gap doesn't matter. For reference, set screws would have the same issue - there would be a gap between the nose bearing and the ring.

You should measure your nose bearing diameter to make sure the part I made fits, or otherwise verify the nose bearing is the same diameter between your engine and mine (3.2 / 3.6), before I send you the ring - no sense wasting postage! I don't have a 2.7 engine, and I am not a Porsche historian, so I cannot do this.

25 ft*lb of torque on the crank bolt will generate thousands of pounds of force. This force is applied to the front of the case via a spring (compressed rubber). It travels through the case, the crank thrust bearing, and back through the crankshaft to the pulley bolt. None of these structures is designed for that kind of force in that direction.

Assuming nothing breaks, you then secure the ring to the nose bearing. First, the clamp ring won't hold thousands of pounds of force. Neither will set screws. Second, if they did, the force holding the rubber compressed would be from the case into the nose bearing and then nose bearing to the ring. The nose bearing to case interface is not designed for axial loads - all you've got is a little 5mm pin in soft aluminum, and maybe some friction. Something will move. Collateral damage may, or may not, result.

Originally Posted by burgermeister (Post 11016799)

bcgreen, I think the only place sealant is needed is between the O-ring and the case. If oil gets past that, then another approach is needed.

I don't know what yamabond is. I would suggest curil-T because 1) it seals quite effectively 2) it is used around the nose bearing O-ring per Wayne's book, so it is compatible with all materials in the interface, and 3) it is completely reversible (just wipe off with alcohol; takes a while, but it will come off). Anything that sticks & cures, especially if it is an epoxy, is not readily reversible without engine disassembly.

The protruding part of the nose bearing measures 60mm for my 3.2, which is the dimension that matters for your project. The diameter of the bearing portion is 65mm, checked with a caliper, not a mic - but that is somewhat irrelevant.

Do you need a ring & washer for pressing the clamp ring into the case, or do you have suitable parts available?