I'm at my wits end. I've got an oil leak at the back of the block. I can't tell if it's the crank, or the cup plugs (or something else?). I reconditioned the block, put all new plugs in (shop did the rifles, I did the cam plug), and I've now done the rear seal 3 times. And now I've got a pretty constant drip out the back (as I did after each rear seal attempt). I know the rear seal is in right, is there something else I've missed? HELP!

Thanks....Jeff

I have a 390 with similar probs, after curing all the oilleaks from rocker covers, inlet manifold etc it still leaks out the rear main. (this motor is producing around 425 hp & has less than 2000 miles on it but was built by someone else before I bought the car)Apparently they all do it. It is luck if you have a 390 that doesn't have some degree of leak past the rear main. It seems to be an inherent design fault in the block.
Last time I checked Keith Crafts site he was not guaranteeing FE rear mains on his motors so if he can't get it right you see the problem you are dealing with.
My engine builder has worked for Ford Special Vehicles & Brabham Formula 1 and has been trying for 30 years to cure this problem with no real sucess yet.
He is going to try something new with the 428 we are building at the moment. We are going to machine the back of the block to accept a modern high tech single peice seal. He has done this on smaller motors & it works.
The other things that will help are using a girdle plate and/or cross bolting the crank to reduce flexing which wears the seal more rapidly.
Sorry I can't offer an easy solution, but if we are successfull on the 428 I will keep this forum posted.

Regards

David

i had that problem and after a few new seals found out it was the rear cam plug installed wrong
i have 2 390s and neither one leaks oil out the rear of them only around the valve covers
gordon

Me too. It sucks but its just an inherent design flaw. Search archives there has been some good info on this fix, but none that are fool proof.

first of all what kind of seal are you using.still got problems contact me.it does take a little extra effort to seal the back of a fe but when done right they will never leak.