biscuit141

As I prepare to do my rear end fluid change, I was evaluating if any other work needs to be done. While I NEVER see any leaks from my rear end in the garage, the rear diff does look like it may have had a leak at one time. What do you think? Can this bushing be changed apart from the diff fluid? Could this be the result of a one-time clogged breather hose? Where is the breather hose located, so I can check it?

SkinNBones

Yes to all the above.

2003XLT

That "leak" is from beating the **** out of the truck

Hanging around turns and spinning your tires

That seal needs to be replaced $12 from ford

udderbrudder

Your pinion seal is leaking. Not too hard to change. It's very important to make sure the bearing preload is correct when you re-install the yoke and nut otherwise you may damage the pinion bearings and it'll whine.Also check the vent (the only hose coming from the diff) as this can cause pressure in the diff and it will leak. This is a good time to change the oil in it. If it's limited slip you'll need a bottle of friction modifier-add it to your new oil.

biscuit141

How do I make sure the bearing preload is correct? Any tips or hints you could give me about this repair? Thanks.

udderbrudder

You'll need an inch/pounds torquewrench and you should replace the collapsible spacer (sleeve) between the pinion bearings. The large nut should be tightened until the specified amount of torque is required to rotate the pinion. I think around 15 lbs/in is within spec.

biscuit141

I found the chilton guide for this procedure and it does not say anything about replacing the collapsable spacer. It did say to use a new yoke nut, which I am not sure is necessary. What should I ask the dealer for as far as the spacer? I already got the seal for $10.82. How hard is it to seat the seal at the right depth?

biscuit141

OK, so here is the Chilton instructions from the DIY sticky post at the top of this forum. It also says to replace the yoke nut, but I am not sure if this is truly necessary. Any advice? This is for a 99 F250 light duty w/ the 10.25 rear end.


Ford 10.25 Inch & 10.50 Inch Ring Gear
A torque wrench capable of at least 225 ft. lbs. (305 Nm) is required for pinion seal installation.
Raise and safely support the vehicle with jackstands under the frame rails. Allow the axle to drop to the rebound position for working clearance.
Remove the rear wheels and brake drums. No drag must be present on the axle.
Mark the companion flanges and U-joints for correct reinstallation position.
Remove the driveshaft.
Using an inch pound torque wrench and socket on the pinion yoke nut measure the amount of torque needed to maintain differential rotation through several clockwise revolutions. Record the measurement.
Use a suitable tool to hold the companion flange. Remove the pinion nut.
Place a drain pan under the differential, clean the area around the seal, and mark the yoke-to-pinion relation.
Use a 2-jawed puller to remove the pinion.
Remove the seal with a small prybar.
To install:
Thoroughly clean the oil seal bore.
If you are not absolutely certain of the proper seal installation depth, the proper seal driver must be used. If the seal is misaligned or damaged during installation, it must be removed and a new seal installed.
Drive the new seal into place with a seal driver such as T83T-4676-A. Coat the seal lip with clean, waterproof wheel bearing grease.
Coat the splines with a small amount of wheel bearing grease and install the yoke, aligning the matchmarks. Never hammer the yoke onto the pinion!
Install a NEW nut on the pinion.
Hold the yoke with a holding tool. Tighten the pinion nut to at least 160 ft. lbs. (217 Nm), taking frequent turning torque readings until the original preload reading is attained. If the original preload reading, that you noted before disassembly, is lower than the specified reading of 8-14 inch lbs. (0.9-1.6 Nm) for used bearings; 16-29 inch lbs. (1.8-3.3 Nm) for new bearings, keep tightening the pinion nut until the specified reading is reached. If the original preload reading is higher than the specified values, tighten the nut just until the original reading is reached.
WARNING
Under no circumstances should the nut be backed off to reduce the preload reading! If the preload is exceeded, the yoke and bearing must be removed and a new collapsible spacer must be installed. The entire process of preload adjustment must be repeated.

biscuit141

Well I changed out the seal today with the help of my dad who is a mechanic. We did not take out the bearings or change the collapsable spacer, it did not seem necessary. After removing the yoke, the pinion seal is right there. We pulled the seal out and put in the new one carefully, reinstalled the yoke after greasing the splines and put on a new nut and torqued it to 160 ft-lbs. We did not even see a collapsable spacer in there, unless you have to remover the bearings to get to it, in which case I'm not sure why that is necessary since the gasket is right in front. Blew air through the vent tube to ensure that it was clear, which it was.

Also changed out the differential fluid as well and installed an aluminum diff cover. Refilled with Vavoline 75w140 full synthetic fluid, which supposedly contains some sort of friction modifier for LS diffs, as well as a 4oz bottle of Motorcraft friction modifier. I have to say, there is a night and day difference in the reduction of my rear end chatter. Probably 80-90% better than it was before. Some turns it seems to be there very little and some turns it is non-existant. Time will tell for sure. I am wondering though if adding another bottle of friction modifier would help reduce any of the remaining chatter. Anyone have any other experiences with this?

mpbball2332

i changed mine about a month and a half ago and it started leaking again and whine was really bad. and im 99% positive that its because i set the preload and extra half turn