Rear main seal leaking

[Rmoore45]

The rear main seal is leaking on my '66 289 engine, its not a bad leak but there is always a small amount of oil on the bellhousing block plate. I'm using synthetic Mobil 1 15-50, could this be my problem? If I were to switch to a conventional motor oil would that solve my problem?

 

[2+2GT]

I doubt it. Oil will find any gap, no matter what the viscosity.

 

[Rmoore45]

I doubt it. Oil will find any gap, no matter what the viscosity.

The only reason I ask this is because I'm also on a jeep forum and a guy had a problem with his rear seal leaking, he was using synthetic oil. When he switched back to conventional, it stopped.

 

[jlangholzj]

usually if they aren't leaking they're empty....lol mine does this a little as well, I'm running rotella T in mine. I've had it apart and back together...seems like i just can quite get it right apparently. I'll try it again once i put a new stall converter in but for now...little leak

 

[PoppyMod]

The rear main seal is leaking on my '66 289 engine, its not a bad leak but there is always a small amount of oil on the bellhousing block plate. I'm using synthetic Mobil 1 15-50, could this be my problem? If I were to switch to a conventional motor oil would that solve my problem?

Hi,
I found you may be able to lessen it even more by creating a closed PCV system. I found this helped my situation when running the Holly and full air cleaner. Reducing crank case pressures which, in part, is what a PCV system does in it's recycling, will benefit minor leaks elsewhere, as well.
Good luck!