front crank seal

[m4250t]

I just had a perplexing situation. I started a freshly built 401 and after running at 2000rpm for 5-10 minutes( flat tappet cam break-in), the front crank seal pushed out rusulting in a nasty oil leak situation. My first thought was case pressure, but I am running a PCV and the oil filler tube was unrestricted. Anybody have experience or thoughts. Randy

[ol' school power]

Are you talking about the metal shell and all coming out or just the rubber?
It would take more than case pressure to push the shell.

[m4250t]

It was shell and all that came out. I am starting to believe it must have been a weak seal or possibly it got started crooked on assembly then weakened as it seated. That's just a guess as I haven't been able to come up with a better theory. I can't believe there was that much case pressure. I will try a new seal and see what happens.

[ol' school power]

There's no way any case pressure pushed out the shell.
How tight did it fit?
Any chance the crank gear wasn't all the way down when you put the cover on? Or a key sticking up during install ?
If it were crankcase pressure, i'm pretty sure it would have blown the pcv out of the hole and possibly the intake end seals and valve cover gaskets first long before a crank seal.

[m4250t]

Yeah, I have been having trouble believing the case pressure theory myself.

It has been about six months since I put the engine together so my recall on the instalation is a little vague, but I am absolutely sure the gear and key were seated before the cover went on.

After we discovered the leak, I was able to reach up there with a small bar and push the seal back in. Of course the seal lip leaked then, but I did think that the seal slid back in a little too easy.

Maybe new seal will make the problem dissapear.

On a happy note, the engine sounded great while it was running.