340 rear main seal leak/gush

340sFastback said

I changed my rear main once with engine in car put in backwards even though I knew correct way. Was dry until I drove it then poured oil out all over the place. Luckily I didn't run it dry. So got to do the job all over again engine in car.

I could never get mine to be 100 percent dry until I put thin film of RTV between block and rear main cap. Otherwise pressurized oil from main oil feed would squeeze out and look like a rear main leak.

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I know that you guys are not going to believe me, but I've never put any sealer between the rear main cap and the block and I've never had any issues with leaks. I use real fine sandpaper to clean out the groove in the main cap and the block and then I throughly clean both grooves out. Cleanliness is the key and to not get in a hurry. I also check the crankshaft for burrs where the seal will ride against. Before I install the seal I check it out for any nicks as I've had a couple that where bad from the factory. I offset the ends of the seal and I put just a dab of sealer on the ends of the seal. By me doing it this way I can honestly say that I've never had a rear main leak, luck, maybe so.