m1078 pinion seal fail pinion nut torque specs

[jimjames]

I have a 95 m1078 with 20000 miles on it I replaced the pinion seal on both axles due to leaks after about 40 miles the rear end seal blew out I believe it is because of improper preload on the pinion nut does anyone know what the torque specs are on the pinion nut thanks

 

[coachgeo]

according to TM's 920-1130 lb-ft (1248-1532 n-m) (links can be found in first forum of this bulletin board)

direct page showing above: http://trucks25tonv1-2.tpub.com/TM-9-2320-365-34-2/css/TM-9-2320-365-34-2_505.htm

check your vents.... it may be clogged thus heat expansion forcing leaks out the seal

 

[jimjames]

thank you coachgeo I checked the vents on both axles before replacing the seals the front axle vent tube was clogged had to straighten a coat hanger out and run it into the tube with a drill to unclog it. the rear wasn't plugged up.

 

[NDT]

Or CTIS seals leaking at the hubs which can apply air pressure inside the axle housing.

 

[tennmogger]

Your predicament sounds familiar. Check out this thread:

https://www.steelsoldiers.com/showt...t-Diff-Pinion-Seal/page2&highlight=120501092E

There's some chaff at the beginning so be sure to read to the end.

Summarizing: My blown seal (on the front pinion) was precipitated by a plugged vent hose and probable leaking CTIS seals inside the axle. Further failures were due to a changed design on the seal itself.

Torque on the pinion nut, if reasonably tight, will not have any effect on the seal.

PS: your total lack of punctuation made interpreting your post more difficult.

 

[jimjames]

I checked both vent hoses on each axle before replacing the seals. The front axle vent hose was clogged, I ended up straightening a coat hanger out and ran it into the hose with a drill. The vent cap was also clogged.
I read the previous thread about the front pinion seal being blown out. I'm sorry about the punctuation I'm so used to texting I hardly ever do any more.
If the ctis is leaking in the axle how hard is that to replace and how do I know if that's the issue.
Not to go too far off subject but my ctis controller works well just none of the lights light up, but if you change modes you can hear it functioning inside the cab. Any idea why the lights wouldn't come on. If I disconnect the plug and plug it back in they light up for a second then go back out.

 

[NDT]

After you replace the pinion seal, I would bubble test for air leaks on the rear axle by opening the oil fill port and checking for bubbles there with the CTIS on. The CTIS can't affect the front axle pinion seal as leaking CTIS air in the hub has no path to the center section through the open knuckle.

 

[jimjames]

so replace the seal. refill the differential. then pull the fill plug out of the end of the hub. let the ctis cycle while looking in the fill plug hole with a flash light to see if the are any bubbles coming out of the oil.

 

[tennmogger]

On my 1994 M1078 the vent for the outer ends of the steering axles have hoses that bridge over to the axle housing, inboard of the Ctis pressurized spaces. Then a single vent hose comes off the right end of the axle housing and is routed to the vent up behind the cab. So a leaking Ctis seal, either an inner or an outer, does pressurize the front axle.

 

[NDT]

so replace the seal. refill the differential. then pull the fill plug out of the end of the hub. let the ctis cycle while looking in the fill plug hole with a flash light to see if the are any bubbles coming out of the oil.

Sorry I should have been clearer. Bubble test means put a wet rag soaked in dishwashing soap or Mr Bubble from your kids bathtub over the hole and see if bubbles are blown. There won't be bubbles in the oil.

 

[jimjames]

what size is the pinion nut I believe it is 2 and 3/16 but cant remember.

 

[scottmandu]

On my 1994 M1078 the vent for the outer ends of the steering axles have hoses that bridge over to the axle housing, inboard of the Ctis pressurized spaces. Then a single vent hose comes off the right end of the axle housing and is routed to the vent up behind the cab. So a leaking Ctis seal, either an inner or an outer, does pressurize the front axle.

Only the hubs will be pressurized on the front axle in the event of CTIS seal failure. The axle tube doesn't share the same reservoir as the axle hubs, unlike the rear.

 

[tennmogger]

Beg to differ, or I am totally misunderstanding your comment. The non-pressurized hub void space on the front axle (where the gear reduction is) has a hose that loops across the pressurized section to the unpressurized axle. Thats how that hub non-pressurized void space is vented. Then the axle has another hose to vent itself plus the linked hub. A failed CTIS seal will pressurize the hub, then the axle housing through the interconnecting hose. Thats why there are two hoses side by side into the axle housing just inboard of the springs on the top of the right end of the front axle.

[edit] I was half asleep when I realized that Scottmandu is referring to the FLUID content of the 'reservoirs', which are isolated from each other, mostly. If there is air moving then small quantities of lube can move. That's why a front hub gear reservoir can mysteriously lose fluid. We can find the FMTV front gear reservoirs are low on lube and wonder where it went. The lube can follow the vented air movement, a drop at a time. This is the same issue found on U1300 (and other) Unimogs that lose hub lubricant by transfer to the axle housing, through the venting system.

 

[tennmogger]

..........Not to go too far off subject but my ctis controller works well just none of the lights light up, but if you change modes you can hear it functioning inside the cab. Any idea why the lights wouldn't come on. If I disconnect the plug and plug it back in they light up for a second then go back out.

Yes, an idea: Check relay 52 on the PDP power distribution panel. It should be a 12 volt 5 pin relay. If a 4 pin relay is present then the CTIS will work but the lights won't light.

Bob

 

[jimjames]

thank you where would I get the correct relay. any auto parts store or is it a specialty part.