440 question, will a rear main seal leak when the car is just sitting, not running?

Challenger340

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This is false information. All rear main seals do not leak.

What is the main bearing clearance .0015-.003. So the crank settles max half of those numbers so .00075-.015. If you believe that “theory” which I do not.

When the engine is running the rods and pistons are pushing down on the crank and so it’s loaded in the down direction anyway. Then when it sits gravity will pull the crank down, but not any harder that the forces when the engine is running under power.


I agree....
NONE of ours leak.... because we test them as above.
 

R413

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The testing doesn’t keep them from leaking.

It is a great thing you are doing that testing to avoid the leak problem, for you and the customer. It says a lot about your business practices! Congrats.
 

dvw

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Lucky or not. I haven't built any leakers.
Doug
 

khryslerkid

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In some cases the pan gasket won't completely seal the two retainer bolt holes and oil will seep under the gasket and it will appear that you have a rear main seal leak when you dont. Fill these holes level with sealant before placing on the gasket.
Screenshot_20200413-145055.jpg
 

R413

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Right next to those holes is a bigger problem. There is a gap and the only solid surface to seal to is the end of the blue side seal for the cap.

Fill that gap with a good sealer like “the right stuff” and have a small amount above the surface and put the pan on, don’t wait for it to set up.

5FA53208-E97A-4007-8455-AA25D2F223BA.jpeg
 

hyde-park

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I've had all the items to do mine since September of 2021. Multiple styles of seals, etc., etc. I've read all the how to's, watched videos, and noted the cases of repeated failures. I just don't want to go to the trouble to do it and have still it leak, lol. Not sure I really want to do this myself or farm it out to someone who has done a bunch of them, successfully.
 

blue69runner

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That seal block need's to have gray Permatex put in the corner's and on the sides where it goes together. That is one of the spot's where it will leak. In stalling this seal is not that big of a job. Doing it your self will save a bunch of money. You will learn as you go. Sound's like a lot of the bases have been covered here.
 

65-440

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I've had all the items to do mine since September of 2021. Multiple styles of seals, etc., etc. I've read all the how to's, watched videos, and noted the cases of repeated failures. I just don't want to go to the trouble to do it and have still it leak, lol. Not sure I really want to do this myself or farm it out to someone who has done a bunch of them, successfully.
Man if you were close to me we could put it on a lift and knock it out quick!
 

MarkLevi

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If the slant in my pick up stops leaking, I know the oil's all gone! Fortunately, slant don't really need oil or water all that much...
 

Vinny

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My leaky oil pressure sending unit on my A12 Bee had me fooled for a rear main leak. I got under the car and watched as my daughter started the car. I was so relieved that the fix was a simple one.
 

blk/wht 69 RR

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Right next to those holes is a bigger problem. There is a gap and the only solid surface to seal to is the end of the blue side seal for the cap.

Fill that gap with a good sealer like “the right stuff” and have a small amount above the surface and put the pan on, don’t wait for it to set up.

View attachment 1253094
Here is my oil pan leak that I can't figure out. I've done all of what has been talked about above, still leaks.
20191031_091837.jpg
20191104_095627.jpg
 

Butch Harley

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this engine does leak but when sitting all the oil in the bell house makes its way to the floor not much but enough to piss you off
 

themechanic

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Its VERY easy to replace the rear main seal in your 440--I do alot of them--to bad your in cali--just clean it up and leak check it--most of the time its the oil sending unit or valve cover gaskts--but the rear main in a 66 is possibly the source--look before you leap--
It's simple, but not easy.
 
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