M1123 differential rebuild in North Texas?

[tjonesdfw]

Drove our new ‘98 M1123 home over the weekend and what had appeared to be a clean/dry rear diff, turned into an oozing mess between the passenger rotor and the diff housing by the time I made the 45 min trip home. Does anyone have a resource for someone that rebuilds or at least reseals diffs in the North Texas area? Assuming it means new bearings, seals, etc. if all the guts are still good. The fluid is tinted green and smells burned which has me concerned too. I hear it’s a hell of a job to get the rear diff out and fixed for one person… I’ve done most everything on my own but never any differential work. While its out, is there anything else y’all recommend doing or modifying?

 

[Slate]

Probably just replace the seal and you should be good. Make sure the diff can breath as well that the vent is not clogged. I was afraid of mine at first but it was easy and straight forward. Just getting it out is the PITA. The seals from what I've read just fail at times. New seal, star washer and some black silicone should be good. 90 weight oil has an odd smell to it. Plenty of videos and threads about it.

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[Mogman]

It is a PITA BUT much easier to just replace the seal than to pull the diff and have it repaired outside the vehicle.
The burnt smell could be because some of the oil got onto the brakes, this goes without saying or SHOULD. You did replace or have all the fluids replaced as soon as you got the HMMWV, yes?

 

[tjonesdfw]

It is a PITA BUT much easier to just replace the seal than to pull the diff and have it repaired outside the vehicle.
The burnt smell could be because some of the oil got onto the brakes, this goes without saying or SHOULD. You did replace or have all the fluids replaced as soon as you got the HMMWV, yes?

I finally found a video of someone doing it while the diff was still in the truck today, with a homemade 2” PVC pipe contraption. We’ve only had the truck home for 48 hours but a full fluid change is on the menu very soon. The transfer pump is leaking too, so concern #1 is whether the internal rubber piece has failed and is letting any fuel migrate into the crankcase… followed immediately by an oil change and a baseline oil analysis. All the cooling lines are caked with the undercoating these marine trucks received, so new hoses and lines are in order too.

 

[Slate]

I finally found a video of someone doing it while the diff was still in the truck today, with a homemade 2” PVC pipe contraption. We’ve only had the truck home for 48 hours but a full fluid change is on the menu very soon. The transfer pump is leaking too, so concern #1 is whether the internal rubber piece has failed and is letting any fuel migrate into the crankcase… followed immediately by an oil change and a baseline oil analysis. All the cooling lines are caked with the undercoating these marine trucks received, so new hoses and lines are in order too.

Just FYI some of the older brackets don't leave room to get the seal in without dropping the diff a bit and if you go that far you might as well take it out. I took mine out and cut out the brackets a little bigger so next time I can just do it in the truck.

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[Retiredwarhorses]

Just FYI some of the older brackets don't leave room to get the seal in without dropping the diff a bit and if you go that far you might as well take it out. I took mine out and cut out the brackets a little bigger so next time I can just do it in the truck.

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all A2 trucks have the newer diff hangar brackets that allow seal removal, even the older version that didn’t, it was still possible to remove without dropping the diff, do it all the time.
It just appears your outp seal is leakin, absolutely no reason to remove let alone rebuild the diff based on pics.

 

[tjonesdfw]

It is a PITA BUT much easier to just replace the seal than to pull the diff and have it repaired outside the vehicle.
The burnt smell could be because some of the oil got onto the brakes, this goes without saying or SHOULD. You did replace or have all the fluids replaced as soon as you got the HMMWV, yes?

One question on fluids... some are saying leave the transmission alone, and others are saying to change the fluid and filter. In my hot rod days, unless a transmission was low or the fluid was dark, you left them alone because fluid changes would sometimes cause issues. What's the general consensus around here?

 

[tjonesdfw]

all A2 trucks have the newer diff hangar brackets that allow seal removal, even the older version that didn’t, it was still possible to remove without dropping the diff, do it all the time.
It just appears your outp seal is leakin, absolutely no reason to remove let alone rebuild the diff based on pics.

Thanks, that'g great news! I had heard from an A1 owner that he had to remove his to reseal and that he put new bearings in when he did his. I wasn't aware of the difference in brackets that allowed it to be done in truck on an A2.

 

[Retiredwarhorses]

One question on fluids... some are saying leave the transmission alone, and others are saying to change the fluid and filter. In my hot rod days, unless a transmission was low or the fluid was dark, you left them alone because fluid changes would sometimes cause issues. What's the general consensus around here?

refer to the lube order…fluids are changed in the military on Time, hours or miles.

 

[Mogman]

refer to the lube order…fluids are changed in the military on Time, hours or miles.

But nobody has any info on when the last service was, so by default they should all be changed.

 

[Retiredwarhorses]

But nobody has any info on when the last service was, so by default they should all be changed.

trucks been sitting in the desert for 10yrs, so that’s pretty much anyone needs to know…but yes, when in doubt, change it.