Axle seals leaking

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
Ever since I’ve got this truck my pinion seal has leaked a tiny bit. Never enough to worry me but still a leak. Also, when stopping and going you can feel the rear end jump. It’s not bone jarring, but noticeable.
Fast forward till a month or so ago and I notice a strong gear oil smell and a layer of oil on both my wheels. Took the vent off and blew it out and replaced. Issue seemed to go away. Now, it’s doing it again but worse. To the point I have oil slinging onto my tail pipe. Do y’all think I could get away with just seals? I see you have to be extremely careful with the pinion for preload. Never messed with axles before. So kinda scary.

So to sum things up, should I replace both axles seals and pinion myself? Do I need axle shaft gaskets as well? And what about the jumping?
 

WVRigrat05

Wound for sound
Jan 1, 2011
3,081
4
38
36
French Creek, West Virginia
Axles are easy, pull brakes, axles and spindles, clean up everything, put new two piece seal in, torque bearing nut to 50 ft lb and back off til keyway goes in and put it back together, make sure you squirt some oil in the spindle or get on a hill so you know the hubs are full of oil. Mark pinion nut and change seal.
 

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
Axles are easy, pull brakes, axles and spindles, clean up everything, put new two piece seal in, torque bearing nut to 50 ft lb and back off til keyway goes in and put it back together, make sure you squirt some oil in the spindle or get on a hill so you know the hubs are full of oil. Mark pinion nut and change seal.

Thanks Reger. Will I need the axle shaft gasket too?
These: https://lincolndieselspecialties.com/i-23846903-gm-oem-rear-axle-shaft-gasket-11-5-2001-2016.html
 

Benny315

Benny
Feb 11, 2019
86
3
8
Backwoods, Savannah, NY
On mine and all the big trucks I have worked on we only used good gasket maker on the axle to hub. I would lift a rear tire and grab the drive shaft near the pinion try pushing it up and down see if there is any slop check u-joints and carrier while down there, if not just simply swap the seal, hardest part is that big nut holding the yoke. Just be careful not to hurt the new seals sliding the hub back on and I spin the hub to feel it's seated and the nut is snug(not tight). Think it was 5 quarts to fill from empty since I did my pumpkin seal as well.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,681
5,831
113
Phoenix Az
Reger pretty much nailed it.

Just make sure you get the old seal part off the spindle before putting the new seal in the hub and putting it all back on.

You can buy new ones of those or see if the old ones on there don’t tear or even just rtv it. Any of those three work well. Just don’t put a torn gasket back on.

Pinion seal, I would first make sure you have 0 play in and out or side to side at the yoke. If you do, stop because your gunna need a rear end rebuild ASAP. If good, continue. Mark the nut to the pinion, make note of how far down the pinion it is and impact gun it off. Might have to make a tool to hold the pinion yoke from rotating if she’s stubborn. Use a puller to pull the yoke and then pry that old seal out and tap in a new one. Tap the yoke back on (don’t go hammering away here) and won’t hurt to use the pinion nut to suck it all the way down. Once you get the nut down and it’s tightening up to the mark, go just a touch past the line. Make sure the nut is down where it should be lengthwise on the pinion. Sometimes you get a false reading on “tight”. You don’t want to go too tight or you compress the crush sleeve too much and mess up bearing preload. The tick past has worked great for me for many years.

Building pressure in the diff is a little concerning though. Is the diff over full? Might not be a bad idea to pull the diff cover and inspect it as well.
 

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
Thanks for the info guys. I need to check if there’s any slop. When you come to a full stop you can feel it sort of “disengaging” of you will. Then as you start going there’s a slight but noticeable jerk. I’ve been running it for a year and a half like this. No info on what has been done to the truck before I got it.

As far as over full, I’ve honestly just been a sorry mechanic and not checked it. Starting to worry that it’s low because of how much and how long I’ve noticed a leak. But not sure where the sudden pressure has come from. I drive the truck a LOT for work and trips. Currently worried I’m about to need a rear end and headgaskets at the same time :(
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,681
5,831
113
Phoenix Az
Clunk is most likely the t-case or slip yoke.

If it needs a rear end, just find one off cl or offerup or junkyard. Cheapest/quickest option and you can swap that rear end in a couple hours
 

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
Clunk is most likely the t-case or slip yoke.

If it needs a rear end, just find one off cl or offerup or junkyard. Cheapest/quickest option and you can swap that rear end in a couple hours

Good advice. Not sure if pump runs has ever been done. That’s on the list too along with checking u joints.
 

MAXX IT OUT

<<<IT WORKS
Mar 1, 2013
1,780
37
48
Des Moines, Iowa
Axles are easy, pull brakes, axles and spindles, clean up everything, put new two piece seal in, torque bearing nut to 50 ft lb and back off til keyway goes in and put it back together, make sure you squirt some oil in the spindle or get on a hill so you know the hubs are full of oil. Mark pinion nut and change seal.


Hum, I think I need to check mine. I just did mine and I believe I did what someone claiming to be a GM teck said was to, which was to torqued it to 52FT LB, then backed it lose and give 1/4 to 1/2 a turn of preload. Might explain why my rotors are dragging on the dust shields when I turn corners.:(
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
21,681
5,831
113
Phoenix Az
Good advice. Not sure if pump runs has ever been done. That’s on the list too along with checking u joints.



The clunk usually isn’t pump rub. It’s the groove cir clip that holds the output bearing in has wallowed and the shift fork and collar have worn out allowing movement inside.

When it gets bad enough, it will cause you to limp because the speed sensor looses signal from the reluctor wheel when you hit a bump under acceleration
 

zakkb787

<that’s not me...
Sep 29, 2014
2,340
52
48
Granite Falls NC
The clunk usually isn’t pump rub. It’s the groove cir clip that holds the output bearing in has wallowed and the shift fork and collar have worn out allowing movement inside.

When it gets bad enough, it will cause you to limp because the speed sensor looses signal from the reluctor wheel when you hit a bump under acceleration

Could explain my shift range inhibited I get occasionally when I put it in reverse and don’t move right away. As well as the limp mode where I’m stuck in first or second when I get off the interstate after a long trip that I thought I had bandaided by a clip to ground the TCM. I’m gonna stop thinking before I find something else wrong with it lol
 

JoshH

Daggum farm truck
Staff member
Vendor/Sponsor
Feb 14, 2007
13,714
776
113
Texas!!!
Axles are easy, pull brakes, axles and spindles, clean up everything, put new two piece seal in, torque bearing nut to 50 ft lb and back off til keyway goes in and put it back together, make sure you squirt some oil in the spindle or get on a hill so you know the hubs are full of oil. Mark pinion nut and change seal.
After torquing, you back the nut off one full turn then no more than hand tight to align the keyway.