Rear main vs tranny input seal leak

[DanEC]

Originally Posted by Texasdoc

Edit: Mods, do you want to move this to the small block forum? It is no longer about transmissions.


Is there a conversion for the percentage between hot and cold?


If not, I guess I'm going to have to warm it up, then (somehow) remove the headers to do the tests. I can't get the adapter port screwed into the spark plug hole with the headers in place.

I could do them all but two and seven, reheat, wait until the headers are cool, the remove and do 2 and 7 before it cools.

Considering all you describe above, I think I would probably do the leak down test on a cold engine. A cold engine piston clearances and ring fit are a bit looser than when the engine is warmed up so the cylinder to cylinder variance may be a little greater. There isn't a conversion factor that I'm aware of and a lot of it has to do with how well your engine bores were machined and the clearances and type of ring pack. Forged pistons often were set up pretty loose. Technology has probably overcome that by now. But - on a leak down you will still be able to listen to see if there is a weak cylinder (or more) are and where it's leaking - out the exhaust, out the intake or in the crankcase.