Rear main vs tranny input seal leak

[DanEC]

Originally Posted by Texasdoc

Cold engine. No oil placed in cylinders. This is with a new leak gauge. Summit Link

Cylinder 1 - 3% leak
Cylinder 2 - 3.5% leak - minimal hiss in exhaust
Cylinder 3 - 2% leak
Cylinder 4 - 4% leak - minimal hiss in valve cover
Cylinder 5 - 3% leak
Cylinder 6 - 3.5% leak - minimal hiss in exhaust and valve cover
Cylinder 7 - 4% leak - minimal hiss in valve cover
Cylinder 8 - 2% leak - minimal hiss in valve cover

I would think that with these numbers, there is not significant blow by. Especially when the engine warms up, the rings should get tighter and less blow by in the valve covers. I'm not sure about the exhaust hiss. I have hydraulic lifters. They may be too tight - they are set at 1/2 turn past zero lash.

No smoke in the exhaust. No water in the oil.

Going to add a 5/8 inch line from the PCV to the throttle body. Going to add a 5/8 inch line from the breather to the intake filter. See what I come up with. No current photos of the motor, but will add photos soon - likely tomorrow, though.

Those are better than good numbers for a cold engine - they're excellent. The 1/2 turn past 0-lash should be good too.

[Jac Mac]

Needed pic to verify correct seal fitment, 'Looks' like the RTV you used may have 'dried' onto crank sealing surface and 'dragged' at start up. I use grease rather than oil at assembly to prevent this.

[RICK LAKE]

Texas Doc Happy easter to start with.
Looks like a problem with the real seal being installed. Either too much RTV or the seal lip was damaged from being off side in the rear cap. You will get this right after a couple of trys. Everybody goes through this.
2 times, IMO throw that Mr gasket breather in the garbage or hang it on the wall. This is why the motor is building up pressure after a couple of minutes at cruising. You motor vacuum is between 10-14 hg vacuum and the small hose with the breather can't supply enough to keep the inside of the motor under vacuum. Pressure builds up and you start leaking. Look for a K&N valve cover filter that looks like a small air filter. If you need a picture, look at dirt track motors. That breather was designed for sitting on the oil fill tube on some old motors like AMC V8 and others with filltubes that stick up about 6" They where hook to the air cleaner but worked both ways of letting fresh air into the motor and letting oil vapor out and being burnt up by going through the carb. Repair this, your oil leaks will be fixed. Happy Easter Rick L.

[Texasdoc]

I removed that filter. See pictures above. Hopefully, all is well now. We will see over the next few days. Thanks for everyone's help.