Front axle 4x4 pinion seal replacement

[Mitch]

Pretty simple DIY. It took less than a hour in labor with the right parts.

Parts you will need:
New seal, about 8 bucks from Napa
T40 Torx bit
1 1/4 socket
2 arm pully puller-I got a cheap one from Checker for 6 bucks, worked just fine
Seal puller (Optional-you can also use a screw driver)
Pinion press (Optional)

I forgot to take a lot of the pictures, as I was trying to get it done to beat the weather that never came.

Start by removing the 4 bolts holding the front driveshaft onto the yoke. Be careful not to strip them out. It found it easier to get them out using air tools, as they are in at an awkward angle. You might need to turn the driveshaft to get to some of the bolts. I just moved the truck forward to rotate.

After you got all the bolts out, you can pull back on the driveshaft and move it out of the way to get to the 1 1/4 inch nut holding the yoke on.
Once the nut is off, install the pulley puller on the yoke, and torque it off.

After that is out of the way, you are gonna see the seal.

Pull out the old seal. It is in there pretty good, so don't be shy with it. I used a seal puller, so it was pretty easy, but it is doable with a flathead screwdriver.

Here is a comparison picture of the old vs new.

Old seal


My seal failed due to mud getting in there, and the dirt drying out the seal.
Here is the back of the yoke filled with junk I picked up over the past 39,000 miles.

A view of the inside of the axle housing, looking at the pinion shaft


To replace the seal, you should use a seal press, but I just used the back of the yoke. If fit on the seal perfectly, and I used a rawhide mallet to hit the yoke to seat the seal.
Here is the new seal installed.


Once thats on there FLUSH, reinstall the yoke,) then the nut. I am sure there is a torque to the nut, but I just made her good n' tight with the air gun.
Reinstall the driveshaft, (it will only go on one way, the teeth line up,) and install the 4 T40 bolts. Again, I am sure there is a tq spec, but I just made em tight.


I was parked nose downhill slightly, so I didn't lose any fluid. I am not sure if you will lose fluid on level ground or not. Thats it, your done.

[Motorbrreath]

that nut applies a preload on the pinion shim for turning torque, id make sure is torqued to the right spec and the turning torque on the pinion is correct.

[Mitch]

that nut applies a preload on the pinion shim for turning torque, id make sure is torqued to the right spec and the turning torque on the pinion is correct.

I had made a mark before I removed it, and tightened it slightly past the mark.

[Cumminalong]

Mitch,

That mark isn't necessarilly what you can go by.

That nut applies the pinion pre-load and needs to be tightened so that, with a used set of bearings, it take approx 20 in/lbs of force using a dial type torque wrench to rotate the differential....that's with everything else out of the axle.

Pinion pre-load, pinion depth, and back lash must be set correctly or you're asking for trouble.

That's why I've said in the past that replacing a leaking pinion seal isn't as easy as just popping the seal and putting the new on in.

[Motorbrreath]

we see alot of diffs come in that have to have new chunks because the preload was too high, causing premature failure. You DEFINATELY dont want that bill....

[NickBeek]

My first front seal was replaced at 70K miles. Today while doing an oil change and lube job I noticed the front was leaking again at 154582 miles. I'm gonna ante up for the OEM seal again for $20 seeing as how it lasted 70K or better both times.