Brand New Rear Main Seal Leaking- Why? (1 Viewer)

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Hi, I would love advice. I'm at a loss. I rebuilt my 5/1973 F engine a little over a year ago. Full rebuild, new cam, etc. It has been leaking since then so I decided to pull the motor and check.

The rear main seal is definitely one of the leaking parts. Does anybody know why/how it could be leaking? Could I have installed it wrong?

I am ready to install the new seal but I'm scared to put it back together before I identify what I did wrong in the first place. I don't want to do the same thing again unknowingly.

20200402_203744.jpg
 

ceylonfj40nut

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Do you have pics of the I install? Crank surface smooth? What do you use to drive seal in? Pre-oiled lip before it went in?
 
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Do you have pics of the I install? Crank surface smooth? What do you use to drive seal in? Pre-oiled lip before it went in?
No I don't have pics. Forgive my ignorance, but I believe I used a mallet and a block of wood to tap it into place evenly.

I don't particularly remember pre-oiling it but I should have known to do so. I probably did.
 

77mustard40

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X2, that’s what I did when I replaced my clutch last year. Another few hours of work mostly cleaning the exposed surfaces and pan before reassembling. Gave me a chance to look at the underside of my 42 year old motor and check the oil pump.
 
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Full rebuild included main bearings I assume?
[eliminate bearing play as the cause]
In the pic it looks like a tiny piece of swarf stuck to the seal. I assume it's on the outside and not lodged between the seal and crank?
 
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You can do a much better job with less stress on the new seal by taking off the oil pan and the rear-most main bearing cap. More work, but the new seal will go on easily and straight that way.
I will probably be replacing the oil pan gasket anyways.

Why should I remove the main bearing cap? How will that relieve the new seal?
 
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Full rebuild included main bearings I assume?
[eliminate bearing play as the cause]
In the pic it looks like a tiny piece of swarf stuck to the seal. I assume it's on the outside and not lodged between the seal and crank?
Yes, it was a full rebuild.

And yes, the fragments, or swarf, that you see are all on the outside of the seal. Thanks for teaching me a new word lol
 
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X2, that’s what I did when I replaced my clutch last year. Another few hours of work mostly cleaning the exposed surfaces and pan before reassembling. Gave me a chance to look at the underside of my 42 year old motor and check the oil pump.
You replaced the main bearing cap?

And how did this help?
 

77mustard40

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You replaced the main bearing cap?

And how did this help?

By pulling the cap you have no issues installing the rear main seal, no hammering it in and hoping. Bearing was fine, it did let me look at the bearing surfaces and get an idea of how my old motor was doing though. Installed the seal and reinstalled the pan, cap and torqued to spec. No more oil leaks.
 

1911

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Why should I remove the main bearing cap? How will that relieve the new seal?

You'll see when you get there. Taking the main bearing cap off completely exposes the rear end of the crankshaft, giving unimpeded 360-degree access, so that the seal can be pushed on by hand. No driving of the seal needed, no hoping that you get it straight.

Edited: @middlecalf and @77mustard40 beat me to it. Should have read the rest of the thread before posting!
 
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By pulling the cap you have no issues installing the rear main seal, no hammering it in and hoping. Bearing was fine, it did let me look at the bearing surfaces and get an idea of how my old motor was doing though. Installed the seal and reinstalled the pan, cap and torqued to spec. No more oil leaks.
By pulling the cap you have no issues installing the rear main seal, no hammering it in and hoping. Bearing was fine, it did let me look at the bearing surfaces and get an idea of how my old motor was doing though. Installed the seal and reinstalled the pan, cap and torqued to spec. No more oil leaks.
@1911

Good to know, thank you guys.

Just to clarify, the caps don't need to be torqued in any specific order? I can remove just the one closest to the rear of the block it and re-install it without harming anything or touching the other caps, correct?

I'm sure it's fine but I thought I'd ask just to be safe...
 

hobbes

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it’s fine. Here’s a old thread on main seal and oil pan gaskets in the FAQs.
 

1911

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Just to clarify, the caps don't need to be torqued in any specific order?

No need to remove any another caps than the rear-most one. Torque each side in increments to 76 - 94 ft. lbs. (for a 2F - check the FSM to see if it is different for your F).

I can remove just the one closest to the rear of the block it and re-install it without harming anything or touching the other caps, correct?

Yes.
 

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