Rear main seal replacement

Mattbo

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Hey guys I'll be doing the SMF and Clutch as soon as they come in and I had planned on doing the rear main seal as well. Ive been researching it and it seems straightforward, but is there anything I should be forewarned about or just remove the plate and install the seal and plate gasket? Or from what ive been reading the paper gasket is not necessary just using high quality RTV is just as good? Any tips or tricks would be appreciated.
 
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WrenchWhore

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Be aware these engines have been in service for a long time so they sometimes have wear sleeves installed over the crank where the seal rides on. If yours doesn't have one then proceed as usual assuming the crank doesn't have a groove worn in it. If it does and it's bad enough it may be time to install a speedy sleeve and seal. Some engines like mine from a U-haul truck had the Navistar sleeve (thick sleeve) and Navistar seal number M41434. If yours had this seal (O.E.M. seal) and you can't locate it Rockauto has a seal that worked with it (SKF 38649). It's larger in diameter to compensate for the thick sleeve. I'm sure another member will chime in but the I wouldn't doubt the speedy sleep seal has a specific seal number as well.
 

Mattbo

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Be aware these engines have been in service for a long time so they sometimes have wear sleeves installed over the crank where the seal rides on. If yours doesn't have one then proceed as usual assuming the crank doesn't have a groove worn in it. If it does and it's bad enough it may be time to install a speedy sleeve and seal. Some engines like mine from a U-haul truck had the Navistar sleeve (thick sleeve) and Navistar seal number M41434. If yours had this seal (O.E.M. seal) and you can't locate it Rockauto has a seal that worked with it (SKF 38649). It's larger in diameter to compensate for the thick sleeve. I'm sure another member will chime in but the I wouldn't doubt the speedy sleep seal has a specific seal number as well.
Thank you that’s what I was reading up on last night. I ordered just the rear main seal made by Timken, but I’m prepared to order the sleeve if need be.
 

Mattbo

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Be aware these engines have been in service for a long time so they sometimes have wear sleeves installed over the crank where the seal rides on. If yours doesn't have one then proceed as usual assuming the crank doesn't have a groove worn in it. If it does and it's bad enough it may be time to install a speedy sleeve and seal. Some engines like mine from a U-haul truck had the Navistar sleeve (thick sleeve) and Navistar seal number M41434. If yours had this seal (O.E.M. seal) and you can't locate it Rockauto has a seal that worked with it (SKF 38649). It's larger in diameter to compensate for the thick sleeve. I'm sure another member will chime in but the I wouldn't doubt the speedy sleep seal has a specific seal number as well.
I somewhat read up on the "Uhaul" seal kit in another thread. It seemed a lot easier and better built. Is there anything like it still in existence? or was that just a thing of the past?
 

WrenchWhore

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I somewhat read up on the "Uhaul" seal kit in another thread. It seemed a lot easier and better built. Is there anything like it still in existence? or was that just a thing of the past?
Seems like a thing of the past to me. Gotta use what's available in 2024 to get these old machines working again. Someone in a Rear main seal post said they found just the Navistar seal from a place in Mexico but it was out of the box and had paint maker on it so I couldn't trust that it had be taken care of. I'd do just what you're doing and order a standard replacement seal. If you have issues then just order the right one as soon as you know. It's a pain and the down time sucks but rear mains are something you must get right or life will suck. This thread had some insite. A little further down on page two I posted a picture of what the Navistar seal and sleeve looks like. I left the sleeve on the engine as it was in good shape and used the SKF seal from Rockauto.

 

Mattbo

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Ok
Seems like a thing of the past to me. Gotta use what's available in 2024 to get these old machines working again. Someone in a Rear main seal post said they found just the Navistar seal from a place in Mexico but it was out of the box and had paint maker on it so I couldn't trust that it had be taken care of. I'd do just what you're doing and order a standard replacement seal. If you have issues then just order the right one as soon as you know. It's a pain and the down time sucks but rear mains are something you must get right or life will suck. This thread had some insite. A little further down on page two I posted a picture of what the Navistar seal and sleeve looks like. I left the sleeve on the engine as it was in good shape and used the SKF seal from Rockauto.

I tore everything apart today, but did not get to inspect the seal or remove the flywheel/clutch simply ran out of time. I ordered the timken rear main as well as a timken throwout and pilot bearing for the perfection clutch kit. I’ll know more when I break the flywheel off and have a better look.
 

Mattbo

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I just finished taking the clutch and DMF out. It was definitely shot. Springs were still tight, but it had about an inch of play. Getting that engine cover off is a bit sketchy whoever sealed it last sealed it very well. There is a tiny groove it’s not that bad. You can see it, but cannot feel it even with your fingernail. It it pretty obvious if a sleeve was installed I’ve looked at a bunch of pictures, but I cannot tell if this is a sleeve or just the bare crank?
 
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Sparks-IDI

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So, if you cannot feel it with your fingernail drug across it, it is probably the shiny spot where the seal was riding. If that's the case clean it up with maybe a touch with a scotchbrite pad only going with the "grain" (direction of rotation). You can check if that is a sleeve on there by measuring with some calipers the hub diameter. I believe there were two diameters of crank hubs, only because on rock-auto a 3.750 and 3.875 diameter seal is listed. Those are the nominal factory hub base diameters I'm thinking. If either is say, .020 to .040 more than the base number, there is likely a sleeve on it.

If you click on Wrenchwhores post #5 above and click on the post he references then back up a page, you will see what I had to deal with a couple of months when I originally posted it. If its smooth like you say, just use it.
 

Mattbo

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I don’t think the seal was leaking so I’d like to get this right and keep it that way.
 

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Mattbo

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I hope so. I’ve never replaced this type of rear main seal before, but it does look like it is naked. I’ll order a sleeve today and get everything cleaned up then attempt putting it on.
 

Mattbo

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With that being said is the rock auto sleeve the better option? I'm looking at Napa to see if there's one locally I can grab. I'd like to get a better maybe easier option instead of what's available first. I already ordered the Timken seal, but understand that will probably not work with a sleeve so will have to return that and get a sleeve/seal that is for the diameter of the sleeve. I have other things i can get squared away if i need to order one (ie degreasing and cleaning up trans/ T-case)
 
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Mattbo

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Well disregard the SKF 99387 on Rock auto says it "requires no change in seal size" I'll order that one and keep my Timken
 

Old Goat

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Did you read through the link in post#5?

I must have done something right even though I was unsure if I was doing things right stumbling along getting the dang rear seal installed.
Put a few thousand miles on her and no leaks.

I put a link of the Rotunda Ford tool to press the seal into the plate using your Hyd Press. Sets the seal at the proper depth.
I see one is listed for $35 if you click on the link.



Goat
 

Mattbo

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Did you read through the link in post#5?

I must have done something right even though I was unsure if I was doing things right stumbling along getting the dang rear seal installed.
Put a few thousand miles on her and no leaks.

I put a link of the Rotunda Ford tool to press the seal into the plate using your Hyd Press. Sets the seal at the proper depth.
I see one is listed for $35 if you click on the link.



Goat
I did it was a good read. I don’t have a press and had planned on taking it to a shop to have it pressed in there. As far as the leaks I get that everything tends to end up at the rear of the engine and “everywhere”
 
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