I have a 2001 Expedition, it has developed a small leak in the front of the rear diff. It seeps a very little amount of fluid around that front seal. I don't have alot of experience with rear ends, but have wrenched on alot of cars. I am wondering how hard it is to put a new seal in it? Any thing special you have to know or what?

 

 

Ya, its not hard at all. If you are doing this at home, make sure you have the park brake on nice and tight to keep the pinion from turning when you are removing the pinion nut and yoke. Good luck

 

WTF is that for? He said the leak is in the front of the rear diff. That would indicate a pinion seal has gone out. The seal you're talking about is the rear diff cover seal which would most likely not end up on the front of the diff.

If the seal you're talking about is the one by where the driveshaft bolts to the pinion then thats the pinion seal. If thats bad take it to a mechanic, as thats a pita to replace. That requires removing the flange from the pinion, then removing the seal, installing a new one, then resetting the preload on the pinion when you reinstall the flange. If you're not familiar with axles then don't mess with it. There are 4 areas that fluid can leak from a rear axle in a 01 Expedition. The breather tube (not typically a problem), the pinion seal, the axle tube seals (would leak by the wheel onto the brakes, and finally from around the diff cover. The diff cover is easy to do. The axle tube seals aren't quite as easy, but not complicates (as you need to remove the axle shafts to do it). The breather isn't too bad either, but the pinion seal is the major pita to change out.

 

Rear diff cover is only sealed by silacon...

 

Replacement of a pinion seal should only be done by a professional. All Ford OEM axles utilize a collapsible crush sleeve between the inner and outer pinion cones and cups (bearings). All crush sleeves are the same, except for 8" (used in Maverick, Granada,etc). Over torqueing will cause the pinion bearings to gall or seize up; this will damage the entire rear axle assembly and will require massive $$$$ and work. Under torqueing will allow the pinion bearings to have play, allowing the pinion seal to leak and allowing the pinion to bump against the ring gear carrier and mill it. Ring and pinion may fail from lube loss and again, massive $$$$ and work will result.

I overtorqued the pinion bearings on my 9" diff. in my 1979 F-150. A cold winter day of O degrees farenheit, I noticed that the yoke was loose; I crawled under my truck and torgued with an impact and hurried off to a Santa engagement. When I got in the truck and moved ten feet--I knew I had a problem which was indicated by a soft scraping noise. I totally disregarded the noise due to the fact I was planning on rebuilding the diff. the next summer. The next summer I removed the diff. and disassembled and found that the pinion bearing cups and cones were spalled. This was from over-preloaded (or over torqued) bearings. The entire axle assembly was full of small shiny steel particles from all of the bearings in the entire axle assembly. The differential side bearings had pitted out as a result of all of the contamination in the axle housing assembly.

Axle housing could not even be cleaned with brake parts cleaner. I had to use a power washer to blast all of the particles out. This goes to show even a professional can make a mistake. I have rebuilt over 3,000 differential assembly in my career; ranging from stock auto and light truck units to class 6, 7, and 8 truck differentials, racing and off-road units.

One thing I reccomend when rebuilding Ford differentials is a solid pinion bearing spacer. Can be obtained by Jegs for about $22.00 (U.S.). This helps to avoid overtorqueing (crush sleeve is eliminated).

 

its not hard to do in your driveway but you need a good selection of sockets cause i think the pinion nut is kinda big,don't remember.and a seal puller is nice to have,as is an impact to get the nut off.i'd check the kingpin for wear too cause i had to replace mine and the spider gear along with the seal,but id let it leak for a while and was runnin low of oil

 

Slapping on a new seal improperly risks complete rear end disassembly.

 

well,as long as you get it in its in there.just use common sense and you can do it.