1966 427 Rear Main Seal Leak

[John M.]

All,

My 66 BB has the dreaded rear main seal leak. I have replaced the seal a few times over the years, but have not been able to fix the issue. I have never removed the engine for a rebuild, thus my efforts have been "engine in" only. Should I assume I have a groove in the crank shaft causing the seal to leak? Any other thoughts would be appreciated.

Regards,
John

[Joe L.]

Re: 1966 427 Rear Main Seal Leak

All,

My 66 BB has the dreaded rear main seal leak. I have replaced the seal a few times over the years, but have not been able to fix the issue. I have never removed the engine for a rebuild, thus my efforts have been "engine in" only. Should I assume I have a groove in the crank shaft causing the seal to leak? Any other thoughts would be appreciated.

Regards,
John

John-------

If the seal journal on the crankshaft is grooved or worn you should be able to see or feel it with the cap and seal removed.

I believe that seals with an off-set lip are available. This way, the lip on the new seal contacts an unworn area of the journal. I've never used one but I think they ought to work well.

[Mark E.]

Re: 1966 427 Rear Main Seal Leak

It's critical to follow the procedure outlined in the FSM; details like properly preparing the mating surfaces, and the location, quantity and type of sealant make a difference. It's also easy to install the seal backwards. There are some good threads on this forum that can help.