Got another 7.3!
Logistics Pro
Joined: Oct 2011
Posts: 3,953
Likes: 120
From: Mcdonough, GA
FTE Leadership Emeritus
Joined: May 2014
Posts: 27,355
Likes: 5,950
From: Lake Hartwell, GA
@jstihl I also had a pinion seal leak a couple/few years ago. I did not have the knowledge to replace it myself, so I took it to a local and trusted mechanic shop. They had it done in an afternoon and their rates are very reasonable. So much so that it is almost silly of me to fight with it myself.
Paul is right about the vent lines. About 4 years ago I completely removed the OEM lines and installed new fiber reinforced lines on the vent ports and routed the lines to where they were previously. I usually give a visual inspection to them when I am changing the oil since it only takes a few seconds and is easy to accomplish. If the vent tubes are blocked, the pressure must go somewhere and it will usually be out the pinion seal or the axle hub seals.
Sometimes when the vent tubes are blocked and the seal is leaking, when the blockage is removed the seal will stop leaking since the positive pressure has been removed. Sometimes, not always...
Paul is right about the vent lines. About 4 years ago I completely removed the OEM lines and installed new fiber reinforced lines on the vent ports and routed the lines to where they were previously. I usually give a visual inspection to them when I am changing the oil since it only takes a few seconds and is easy to accomplish. If the vent tubes are blocked, the pressure must go somewhere and it will usually be out the pinion seal or the axle hub seals.
Sometimes when the vent tubes are blocked and the seal is leaking, when the blockage is removed the seal will stop leaking since the positive pressure has been removed. Sometimes, not always...
Its Comin Right for us!
Joined: Feb 2005
Posts: 12,206
Likes: 2,663
From: GA
Thanks for the heads up on diff fluids sous, got under the truck today and what I thought was just the rear diff cover leaking, I then realized it's the pinion seal. Just my luck. Is this pretty difficult to replace ? I read a write up on fte earlier and it seems like a pita but it was the posters first time doing the pinion seal so not sure if he was making sound harder than it is...
Remove pinion nut, i can let you in on a trick with a break bar, pipe and 4x4 if your impact wont break it loose
use a seal puller, or prybar, screwdriver etc to remove old seal. carefully install new seal. I dont have special tools, i just use series of brass drift, punches etc and work new seal in.
When you pull the yoke look at the sealing surface, if there is a groove that will stop a fingernail you might want to consider a speedi sleeve and seal.
your supposed to use a new pinion nut, but i never do unless im installing a new set of gears.
Key here is this rear uses a crush sleeve to set pinion bearing preload, it takes a ton of torque to actually "crush" the sleeve and change the torque, but a good 1/2" impact will do it. so just tighten it back"good n tight" and dont hold the yoke completely stationary when re-tightening and you should be fine.
This isnt the "correct" way to do it, but it how it gets done in the real world 95% of the time. Correct by the book says use new nut and crush sleeve, which means pulling the chunk so you can accurately check pinion bearing preload, and all the stuff that goes with that
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Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
Well I'm pretty sure I found the vent tube, is a rubber tube just on the left side (driver side)of rear diff going into the axle? Tube kinda plugs onto a fitting which goes into the axle. I disconnected the tube at the fitting and blew into it up towards the truck bed and it seemed to blow through relatively freely being that there is a fitting on the top end of tube( maybe a check valve to keep it from getting plugged up). I was really hoping that tube was plugged hahaha! I cleaned off the rear diff and will keep a eye on it to make sure it's the pinion seal. Thanks for the tip on that guys.
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Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
Pinion seal isnt hard, remove ujoint straps set driveshaft on ground being careful not to loose ujoint caps(unless you have flange style).
Remove pinion nut, i can let you in on a trick with a break bar, pipe and 4x4 if your impact wont break it loose
use a seal puller, or prybar, screwdriver etc to remove old seal. carefully install new seal. I dont have special tools, i just use series of brass drift, punches etc and work new seal in.
When you pull the yoke look at the sealing surface, if there is a groove that will stop a fingernail you might want to consider a speedi sleeve and seal.
your supposed to use a new pinion nut, but i never do unless im installing a new set of gears.
Key here is this rear uses a crush sleeve to set pinion bearing preload, it takes a ton of torque to actually "crush" the sleeve and change the torque, but a good 1/2" impact will do it. so just tighten it back"good n tight" and dont hold the yoke completely stationary when re-tightening and you should be fine.
This isnt the "correct" way to do it, but it how it gets done in the real world 95% of the time. Correct by the book says use new nut and crush sleeve, which means pulling the chunk so you can accurately check pinion bearing preload, and all the stuff that goes with that
Remove pinion nut, i can let you in on a trick with a break bar, pipe and 4x4 if your impact wont break it loose
use a seal puller, or prybar, screwdriver etc to remove old seal. carefully install new seal. I dont have special tools, i just use series of brass drift, punches etc and work new seal in.
When you pull the yoke look at the sealing surface, if there is a groove that will stop a fingernail you might want to consider a speedi sleeve and seal.
your supposed to use a new pinion nut, but i never do unless im installing a new set of gears.
Key here is this rear uses a crush sleeve to set pinion bearing preload, it takes a ton of torque to actually "crush" the sleeve and change the torque, but a good 1/2" impact will do it. so just tighten it back"good n tight" and dont hold the yoke completely stationary when re-tightening and you should be fine.
This isnt the "correct" way to do it, but it how it gets done in the real world 95% of the time. Correct by the book says use new nut and crush sleeve, which means pulling the chunk so you can accurately check pinion bearing preload, and all the stuff that goes with that
Its Comin Right for us!
Joined: Feb 2005
Posts: 12,206
Likes: 2,663
From: GA
no problem, i can go into more detail if you decide to. Ive probably done 15 or 20 over the years on sterlings, dana, ford and aam axles
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Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
on a positive note after I blew through the vent tube and cleaned off the rear diff oh, I haven't seen the pinion seal leak in the oil yet
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Cargo Master
Joined: Sep 2015
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thanks Kubota, I flew out the vent tube and cleaned off the rear diff and haven't seen it leaked yet so maybe I will get lucky. Can you take a look at the pic I posted of the rear diff plug. If the rear diff has never been opened up in 170,000 miles would that amount of metal flakes be okay or am I in trouble?
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Cargo Master
Joined: Sep 2015
Posts: 2,860
Likes: 365
I'm not sure, I looked at the axle code on the door sticker and it is blank where the axle code is supposed to be..... another quick question is I realized my truck has a second alternator, is there a reason for that? I thought The second alternator was only on vehicles like ambulances and such
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