322" nailhead rear main leak ?

I'm hoping that someone can shed some light on this, and save my sanity.

I have rebuilt a 1956 322" Nailhead, installed the fel pro neoprene lip seal and face this issue. Part # BS40613

On cold start up, no leak, at 160-165 water temp, it starts to drip, this is when after the initial break in, I have usually just shut it off.

After replacing the seal with another new one, & hoping that would cure the leak, same issue.

This time out of frustation, I let it run up to temp and open the 180 Degree thermostat.
As the motor got warmer I noticed that the leak started to slow to a very slow drip. WTF! This makes no sense to me.

I took it for a 5 Minute drive, came home and parked it on fresh cardboard and maybe 2 or 3 drops of oil on cardboard the following morning.

Can anyone explain what is happening with the seal and the temperature sensitivity.

Thanks in advance.

 

Nobody?

 

If it helps I rebuilt one also for a friend last year and have the same problem although we have not yet rectified it, and its getting worse...If you find a fix post it here.

Now if your question was about lifter gallerie plugs and noisy lifters that I am now an expert on... Dont ask me how I know....

 

Did you put RTV on the seal where the ends meet?

 

Yes, I put a tab of rtv on the seal ends, and even clocked them away from the block,cap split.

2 New seals and the same result.
I'm starting to think that maybe the crank surface where the seal lip rides has some imperfection?

Other than this annoying leak the motor is great.
Any other thoughts or ideas are appreciated.

 

Is the crank in that area smooth, cross hatched, or a little worn looking?

 

Wear or some sort of damage on the crank in the seal area would be my thought.

 

When the crank was out, you should have cleaned the seal area with fine crocus cloth. If you put in another seal, lube it well where it touches the crank. Are you sure its the rear seal and not the rear cam plug?

 

Good point on the cam/lifter journal area being the culprit.

I borrowed a bore scope and checked it to rule it out.
I wish that it was a cam plug, at least I think, I know how to fix that.

I did lube each seal at install, so I think that should not be the cause.

I'm slowly resigning myself that the crank surface must be the problem, and that a Rope Seal.... Ugghh! will be the next step.

If any other thoughts or ideas, I'm all ears.
Thanks for everyones input.

 

I read in a book sometime ago when you replace the rear main seal put a couple of pivots with a hole punch where the seal go because the tend to slip when engine is running and thats what causes the leak!

 

I was not aware that Fel Pro made a lip type seal for the 322. I think I would have known that because about a year ago I had a 322 that I had tryed 11 different rear main seals in with no success.
Best gasket gave me a prototype lip seal to try and I even found some real ***bestos material to try but nothing worked. I ended up buying another engine for the customer and it still leaks to this day.
The only thing I can tell you is look at the back of the early nailhead cranks and you will see that they are mostly hollow from where the converter registers in the back of the crank leaving a thin area right where the seal area is. Drop the pan and remove the rear cap, put a dial indicator on the seal area and see if it is still round. If not , the converter could be distorting the crank at the register. Good luck to you.

 

i rebuilt a 425 a year back and it does the same thing. i think they just leak i gave up after the 5th time of pulling the engine and resealing what i though was leaking. i got mine down to a drop a day but i think i will just live with that.

 

I use the neoprene rear main seals from a 3.8 v6 for the 364/401/425's. I also use an early 70's 455 timing cover seal instead of the rope there as well. I've posted the numbers in the past, I can dig them up if needed.

 

I've heard from a very reliable engine builder that is one of the biggest causes of leaks... It's a tip some editor put in a magazine a thousand years ago, and has caused nothing but problems ever since.

There is a small bit of squish built into the ends... they're just a liiiiitle long. When you crank down on the cap, it squishes those ends together. When you rotate the seal, you're no longer squishing those ends together, and because the excess material is now located elsewhere, the seal deforms and you end up with a leak.

Install it the way the factory meant it to be installed, and see if that helps.

-Brad