rear main seal (1 Viewer)

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while i am getting ready to install a sm 465 in my stock 2-f 73 fj-40 i read this would be a good time to replace the rear main seal , looking at the book there is not alot of detail. since i have never done this i could use some help as far as after pulling the pan what am i looking at as far as replacing the seal i checked the technical links but didnt find anything thanks for the help ! and yes its leaking not much but enough since i am in this far why not thanks again
 

John Smith

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You don't pull the oil pan to replace the rear main seal. You pull the tranny/transfer, remove the clutch and flywheel and the rear main seal is found there on the back of the crank.

It can be a PITA to install a new one without messing it up so take your time as the seal is not cheap.

And since a picture is worth... This is what a leaky one looks like.
crawl 071.jpg
 
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thanks john, so whats the trick installing the new seal ? and do i have to do anything special before putting it in . i just want to make sure i dont screw it up thanks !!!!
 

John Smith

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Grease up the inner surface that rides on the crank and RTV the outside of the seal surface that mates to the block. Either drive it home with the mother of all seal drivers or a huge socket or do what I had to do and gently tap opposite sides of the seal while holding the opposing side so it will not pop out. Eventually you will drive it home.

If you bugger up the seal bite the bullet and buy another or you will just have to pull the tranny all over again to fix the leak.
 

Trollhole

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Buy two seals you can always keep one for the next time if you don't screw one up. That being said I don't have an extra one.:doh:
 
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Trollhole said:
Buy two seals you can always keep one for the next time if you don't screw one up. That being said I don't have an extra one.:doh:



Ok, so I got my two seals...



Now what the hell am I supposed to do with 'em?


seal.jpg
 

spotcruiser

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I've screwed up a bunch of seals trying to just tap them in evenly. Found that I could use the flywheel to seat them. Get the seal started so that it stays in place. Put the flywheel on (line it up with the dowel properly) and tighten the flywheel bolts slowly in a criss-cross pattern until the seal is mostly seated, then pull the flywheel off and gently bottom out the seal with a soft-faced hammer.

Agree with the previous advice to buy two seals before you start.
 
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It's a good Idea to run it before you put the tranny on as well to see if it is still leaking.
 

Poser

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so...

install the flywheel and starter...run the truck...then remove flywheel to check?
 
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Poser said:
so...

install the flywheel and starter...run the truck...then remove flywheel to check?


Naw, you just see if it drips after you shut it off. A leaky seal will always drip.


:beer:
 

Poser

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treerootCO said:
I use the optput cone/cover of the t-case. SST that is always with the truck :)



As a seal driver?
 
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Landcrusher,

There's a freezeplug into the oil gallery to the left and upward from the crank (10: o'clock or so) that makes a mess much the same as a rear main does. It's good to change that plug while you're there.
 
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landcrusher909 said:
thanks john, so whats the trick installing the new seal ? and do i have to do anything special before putting it in . i just want to make sure i dont screw it up thanks !!!!

I did this about a month ago. As others have said, put a light coating on the seal. Then SLOWLY try to push it in my hand as much as you can. It won't get too far in but you will know if it is evenly seated this way. From there LIGHTLY tap it in a circular motion insuring that it evenly goes in (I used a rubber mallet). Mine went in pretty easily this way and I am no pro mechanic to say the least.;)
 
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honk said:
Landcrusher,

There's a freezeplug into the oil gallery to the left and upward from the crank (10: o'clock or so) that makes a mess much the same as a rear main does. It's good to change that plug while you're there.

There is also a cam plug at 2 o'clock that tends to leak. I have seen more of these leaking than main seals. leaky main seals tend to sling oil off the back of the flywheel, so you can tell right away if the main is leaking. The freeze plug and cam plug tend to just leak down the back side of the engine.
 
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Pin_Head said:
There is also a cam plug at 2 o'clock that tends to leak. I have seen more of these leaking than main seals. leaky main seals tend to sling oil off the back of the flywheel, so you can tell right away if the main is leaking. The freeze plug and cam plug tend to just leak down the back side of the engine.

Do you recommend using a sealer on the plugs?

If so, what kind? A hard drying anaerobic thread locker type, or an RTV type?

.
 
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I'm not sure if this is the right way......I usually prep it like mentioned above and try putting on with my hand, tap it a little and once it feels like it's in, I then use a small piece of 2x2 and lay it on top of the seal and tap on the 2x2 until the seal is in. I have not messed up one yet.


And to remove a bad seal I usually try prying it off with a seal puller or if that does not work I usually drill a hole or two and install screws and remove the seal with a hammer as you were pulling out nails. Got this tip from Pinhead a while back and it works wells. :)
 

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