rear main seal - how to replace

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1,653
Location
San Antonio, Texas
My rear main seal is leaking a bunch on my 70 MK III w/stock 460 and trans. I'll be pulling the tranny soon to replace the flexplate so I was thinking I'd whip out the rear main seal while I was at it. Some questions... 1. Am I making things worse or better by wanting to do the rear main seal at the same time as the flexplate? 2. Fel pro makes two kits, both are two piece, one is rubber the other is "vitron" - which is better? 3. Do I have to drop the oil pan? 4. If I have to drop the oil pan, is there anything I should do with the oil pickup assembly? (seems to be oiling fine) 5. If needed, will dropping the oil pan be harder with the tranny removed? 6. I know I'll need two new exhaust donuts and a oil pan gasket, anything else you can think of?
 
Messages
476
Location
Virginia
The rear main seal and flexplate replacements can be done at different times, as the rear main seal is accessed by removing the oil pan. Removing the oil pan will be easier with the transmission out of the way. Be SURE you can actually pull the pan off with your crossmember clearance. Remember the pan has to move down quite a ways to clear the crankshaft before pulling it back and out. Viton is a highly chemically resistant flouroelastomer, and highly temperature resistant. I don't think you need it in your 460. However, if you can look at both seals, I would purchase the softer feeling material, as it is more likely to seal perfectly if the groove is very deep on the sealing surface of the crank. But, probably either would work fine. The total pain will be the R&R of the oil pan and making sure it is sealed well so you dont have any new leaks.
 
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3,775
Location
Houston, Tex
In theory, removing the transmission and flexplate would give you more angle to get at the seal. But in practice, unless you have the rear of the engine suspended from above, once you remove the transmission and the oil pan you will have no support for the rear of the engine. And be sure you don't just assume that the rear seal is the cause of the leak. Upper engine leaks can easily make it down to the ground.
 
Messages
22,648
Location
Apple Valley, California
The rear main seal is held in place by the rear main cap.I have found it easiest to remove the rear main cap then to loosen the other main caps.This will let the crankshaft drop down enough to get the upper part of the seal out. Since you need to replace the flexplate anyway I would pull the engine out and do both of these things on the stand.
 
Messages
5,091
Location
USA
The rear main will be the old rope style,you will need the KD kit that has a threaded end and a chinese finger arrangment to fish the top part of the rope out.
 
Messages
476
Location
Virginia
I agree with Chris idea of pulling the engine and doing it on the stand. If the main seal is leaking you probably need all new gaskets and a good cleaning.
 

sasilverbullet

Thread starter
Messages
1,653
Location
San Antonio, Texas
Originally Posted By: Jeff_in_VABch
I agree with Chris idea of pulling the engine and doing it on the stand. If the main seal is leaking you probably need all new gaskets and a good cleaning.
This is the way I'd prefer to do it. Someone over on a Lincoln specific forum said that it may not be the rear main seal leaking. He said "...one of the galley plugs on the rear end of the one transmission bolt going trough the china wall (back of engine)..." I'm thinking the best way to go is to just pull the tranny and replace the flex plate, checking the bolts mentioned above for leaking and seal them up. Then bolt the tranny back up. Then pressure wash the engine while up on the lift and then check for where the leaks are coming from and the amount of leakage and then figure if they warrant pulling the engine and doing a re-seal. The timing chain is fairly new, but as with any old engine, lot's of things are a little leaky!
 
Messages
8,576
Location
Ohio
You might be able to pull the engine and trans as an assembly then work on it out of the car and reinstall it as an assembly. That might be the easiest way to fix both issues especially if you don't have a lift and a tranny jack.
 
Messages
404
Location
Tampa, Florida
I performed a rear seal replacement on a 1963 Ford Galaxie FE by jacking up the engine with the engine mount nuts off and putting pieces of 2 by 4 between the engine and mounts. Then I could remove the pan. I stuck an aluminum nail in the oil hole in the crank journal so it protruded about a quarter inch or so. I turned the crank with a breaker bar on the front pulley nut. The protruding part of the nail pushed out the top half of the seal and I slid in a new one. It was a lot of work but easier than pulling an engine.
 
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