Pinion seal is leaking static @ about one drop every 7 seconds. It just happened yesterday. And already under coated the chassis, spare tire, and rear suspension. Removed plug, and 1 1/2" low after 130 miles. Took next two days off to fix it. If I drive and fluid gets low enough, might burn up the sure-grip unit. Wasn't leaking before. Have changed fluid at intervals, so I know it was full. Found a small chunk of rubber (seal piece) and what looks like thick plastic coming from between seal lip and yoke.

Looking for words of wisdom on replacing the pinion seal. Main question is what to use to to hold the pinion yoke from spinning while removing and then reinstalling the yoke nut. It's torques to 440 ft/lbs minimum, pending pinion rotation torque. Manual calls for a yoke holder wrench PN 6719. Any ides?

1. Will it hurt the ring and pinion assembly by breaking the yoke nut loose while the weight of the truck is still on the ground? i.e., not on jack stands. Besides worried about causing damage to the rear end, I still have to have it on jack stands to check the pinion bearing pre-load before removing, and after reinstalling the yoke nut. The wheels and brake drums have to be removed.

2. I was thinking of a large ford wrench with a cheater bar leveraged to the ground? Had thought about using a large pipe wrench, but don't want the jaws leaving deep marks due to stress crack points.

3. Where would I get the wrench 6719? Maybe dealer has it in stock. Isn't going to be Auto Zone or Checker.

4. Does the yoke nut have to be replaced? I read that is common practice.

I thought about taking it to a shop, but normally preform my own maintenance and have trouble trusting someone I don't know to work on my vehicles.

Any ideas, folks? Your help would be appreciated. Thank you in advance, Tony.

 

You have to take the carrier out of the housing to replace it. (I think you already know that)

I did mine about a month ago...

Well, I didn't - a shop did.

If you feel slightly uneasy about doing it, just let someone else do it, and usually they will let you stay in the shop and watch...

 

First off, the carrier does NOT have to be removed. Just take the pinion nut off, remove the yoke ( sometimes a hammer is necessary) pry the seal out, and reinstall new seal, yoke, then nut. The rotating force measurement is nice if you have the stuff to do it, but not 100% necessary. I have done many without it. The wrench 6719 is just a big piece of steel that bolts to the pinion. You can either make one youself, or use a large pipe wrench. Very easy fix. If you can change your own oil, you can do this!



PINION SEAL
REMOVAL
Raise and support the vehicle.
Scribe a mark on the universal joint, pinion yoke, and pinion shaft for reference.
Disconnect the propeller shaft from the pinion yoke. Secure the propeller shaft in an upright position to prevent damage to the rear universal joint.
Remove the wheel and tire assemblies.
Remove the brake drums to prevent any drag. The drag may cause a false bearing preload torque measurement.
Rotate the pinion yoke three or four times.
Measure the amount of torque necessary to rotate the pinion gear with a (in. lbs.) dial-type torque wrench. Record the torque reading for installation reference.
Hold the yoke with Wrench 6719. Remove the pinion shaft nut and washer.
Remove the yoke with Remover C-452 Yoke Removal
Remove the pinion shaft seal with suitable pry tool or slide-hammer mounted screw.
INSTALLATION
Clean the seal contact surface in the housing bore.
Examine the splines on the pinion shaft for burrs or wear. Remove any burrs and clean the shaft.
Inspect pinion yoke for cracks, worn splines and worn seal contact surface. Replace yoke if necessary
NOTE: The outer perimeter of the seal is pre-coated with a special sealant. An additional application of sealant is not required.

Apply a light coating of gear lubricant on the lip of pinion seal.
Install the new pinion shaft seal with Installer C-3860-A and Handle C-4171
NOTE: The seal is correctly installed when the seal flange contacts the face of the differential housing flange.

Position the pinion yoke on the end of the shaft with the reference marks aligned.
Seat yoke on pinion shaft with Installer C-3718 and Wrench 6719.
Remove the tools and install the pinion yoke washer. The convex side of the washer must face outward
CAUTION: Do not exceed the minimum tightening torque when installing the pinion yoke retaining nut at this point. Damage to collapsible spacer or bearings may result.

Hold pinion yoke with Yoke Holder 6719 and tighten shaft nut to 285 N·m (210 ft. lbs.) Tightening Pinion Shaft Nut Rotate pinion shaft several revolutions to ensure the bearing rollers are seated
Rotate the pinion shaft using an (in. lbs.) torque wrench. Rotating torque should be equal to the reading recorded during removal, plus an additional 0.56 N·m (5 in. lbs.) Check Pinion Rotation Torque
CAUTION: Never loosen pinion gear nut to decrease pinion gear bearing rotating torque and never exceed specified preload torque. If rotating torque is exceeded a new collapsible spacer must be installed. The torque sequence will then have to be repeated.

If the rotating torque is low, use Yoke Holder 6719 to hold the pinion yoke Tightening Pinion Shaft Nut and tighten the pinion shaft nut in 6.8 N·m (5 ft. lbs.) increments until proper rotating torque is achieved
NOTE: The bearing rotating torque should be constant during a complete revolution of the pinion. If the rotating torque varies, this indicates a binding condition.

The seal replacement is unacceptable if the final pinion nut torque is less than 285 N·m (210 ft. lbs.)
Install the propeller shaft with the installation reference marks aligned.
Tighten the universal joint yoke clamp screws to 19 N·m (14 ft. lbs.)
Install the brake drums.
Install wheel and tire assemblies and lower the vehicle.
Check the differential housing lubricant level.

 

if youve eaten a pinion seal theres a chance the bearing is bad allowing the shaft to beat up the seal. Try checking it for play. If youre taking the guts out of the axle Id just buy a rebuild kit and do all the bearings and stuff in one shot.

 

My fault, I meant the bearing...

 

ruhroh.. yeah thats gonna need taking apart.
in that case you really may as well do the whole deal.

 

I think it failed due to thermal differences. Only have 51K + miles on the truck. Been driving it around Las Vegas with 110 degrees in the summer and got down below freezing this winter. I was up North in the mountains or just getting back when the seal blew. I was driving through snow up there.

The other possibility is a compatibility issue with the OEM seal and the synthetic diff fluid used. I put in Mobil 1 synthetic with a Sta Lube brand limited slip additive.

There isn't any play in pinion bearing. Both in-and-out and side-to-side, no play when I grabbed the yoke and tried to move it. Drive shaft was disconnected.

The torque wrench was going to cost ~ $450.00 and had already paid $100.00 for a 3/4" drive socket and breaker bar. Called two rental places for a large torque wrench, too. Didn't have one. After spending a full day looking for a torque wrench that would go th 440 ft/bls, getting a socket for the yoke nut, and looking for a puller, I gave up and made an appointment with the local drive-line shop. I don't trust the dealer.

I just want to make sure they do the before and after seal replacement pinion bearing pre-load rotating torque check. If the pre-load isn't properly set, the bearing will prematurely wear out.

Thanks for the help guys and will let you know how it turns out at the shop. I plan on staying there and watch them change the seal.

Tony