What a pain in the butt...Sorry for the long post and thanks for
any help!
I just dropped a 390 into my '76 F150 4x4 and am running the usual gambit of trying to stop oil leaks. I replaced the valve covers due to both of them leaking (3 sets of gaskets and pounding flat later),
and now I have a leak around the back of the oil pan, but only at RPM's greater than 2000.
I removed the pan on Saturday, pounded it out again (actually looks perfect), installed a new gasket, and I still have the same thing.
I removed the dustcover (oh yeah, manual transmission as well), and I can see a drop of oil on the crank lobe (I think this is the part of the crank that the pilot bearing is in).
My buddy who helped me seems to think the rear main is no good..I think it may still be the oil pan.
Any ideas? I've watched the oil pressure, and it doesn't seem to get
high enought (around mid gauge range) to push it out, and I've replaced the PVC valve and hose, so I should be ventalating properly.
Again, it doesn't leak just sitting there idling, only at higher rpms, and then it squirts pretty good.
Thanks for any and all help.

 

Dutch,
Your describing a rear main sesal leak. An oil pan leak is unusual. If you've got the oil pan off, drop the rear cap and replace the seal. It's two piece. You'll have to push the top part out with and ice pick or something. Install the new seal. Lube it up with some white lithium and retorque the cap.
My Way is the Highway
KingFisher

 

Darn.. I was afraid you'd say that.
Thanks for the info.

 

You make it sound like it's pretty easy...here goes.

I've checked around on the board, and here's what I think needs to happen (please let me know where I'm off).
Drop the oil pan.
Remove rear cap (do I need to loosen all caps a little to allow
the crank to drop down say 1/32nd or so?)
Somehow grab hold of the top seal and rip it out.
lube up the other top seal an slide in place (should I buy that
tool for this?)
insert the side seals (dab ends with permatex)
put cap seal on cap, lube with white grease (lithium)?.

This motor only has roughly 40 miles on it..can I expect this to be
pretty tough to do since there is little wear on everything?.

Thanks again!

 

A little help here??
Thanks

 

You only have to remove the rear cap. That way the bottom half of the seal can come up and you can access the upper part of the seal. Get a rass punch and a small hammer and start driving out the top half slowly. Get a hold of it with pliers (when you can) and continue to remove it. Then slowly put the new seal back in, being careful not to damage the rubber on it when it is sliding back in. It is much easier than it sounds. Good luck...

 

Thanks!

 

Dutch,
If that motor only has 40 miles on it that rear main seal should be new. It sounds like someone may have put it in backwards!

Don

 

 

Finally got it in. Turns out the bottom half of the seal was...you
guessed it...in backwards:-X23 .
Can't believe that, it being a new engine and all.
I'm just glad it's finally over. Thanks to everyone for the help.
It sounds a lot more difficult than it really is. Took me about 1 1/2 hours start to finish. The majority of time was dropping the oil pan.

Thanks again!!