I was under the truck yesterday trying to replace the rear parking brake cable when I noticed oil originating from between the rear drive shaft and differential. After checking some sources, I think I have it narrowed down to the pinion oil seal. Does this seem right, or could it be something else? Also and if it is the pinion oil seal, how difficult is it to replace. The Haynes manual makes it sound pretty easy, but personal experiences would be nice.

The truck is a 1981 SR5 Shortbed 4x4. The odometer quit working at 248k mi.



Here are a couple of other shots - before, during, and after the paint job.

 

mine is doing the same thing, your right in saying the pinion seal, but in my case I am not so sure the seal is bad, since I believe my diff breather valve is stuck shut not allowing pressure in there to bleed off properly causing it to push fluid past the pinion seal.

I don't know if this can be a cause as I do not know how well those seals are actually supposed to seal.

In my case once I get around to it, I am gonna get rid of the breather valve and extend it putting a filter on the other end and see if my leak goes away. IMO this would be the cheapest easiest way to see if you really need a new pinion seal or not.

If it doesn't stop the leak your mod isn't for nothing though as it's done alot just to help prevent water and such from being sucked into the diff during water crossings etc etc.

 

Pinion seal is a good bet, but like xxxtreme22r mentioned, make sure your breather valve isn't clogged. Just take off the cap, unthread it, and blow through it. If it's clogged, try soaking it in brake cleaner or something. That's all it took to unclog mine. Like he mentioned, a lot of times the pinion seal leaks because those valves are clogged, and the pressure forces fluid out through the pinion seal.

 

Thanks for the input. The PO did put a differential breather that extends up to between the bed and cab. I will take it off and try and clean it to see if it works.

Any ideas on how difficult a pinion seal is to replace?

 

There super easy to replace. Search on 4crawler's site, he has a very good write up with pictures. I would get it for you but I am on my phone inbewteen meetings.

 

Yep, so easy even I can do it. 4crawler's site is the place to go. Just remember: unless somebody messed with it before you bought it, we don't have crush sleeves, we have a solid spacer. You'll know what I'm talking about when you check out his site.

 

I checked out 4Crawler site (been there before but didn't think about the pinion seal write-up) and it looks pretty easy. Also thanks for the crush sleeve input. I had begun to look for the crush sleeve on the exploded differential views available at toyotapartszone and could not find the part number.

After looking further into the leaks, I also noticed oil leaking from the front and rear pinion seals and the front and rear output seals on the transfer case. I guess after > 250k mi things start to wear out. I haven't yet diagnosed for breather clogs, but I figured it would be a good maintenance/learning experience.

Ordered up all the seals and new nuts, and now have to find some time to pull everything apart. I'll probably be back with some more questions.

 

Yeah, all the pinion seals are pretty basic. I think the t-case ones might be slightly more involved (?) but I don't remember right now. Not much more involved, though, if at all.

Yes, those are all things that were leaking on my truck, too. By the way, nice truck and nice job on the paint! I'd love to get after my paint job, but just can't bring myself to spend that much time & money on something cosmetic just yet. Someday down the road...

 

The paint job wasn't that expensive although I did cheap out. I think I spent more on sand paper, abrasive pads, tape, etc. than on the paint. Instead of primering the truck after the sanding, I bought a direct to metal paint used in industrial applications (fork lifts, utility vehicles, etc). I got it from the local auto paint shop for ~ $110 per gallon (including paint, thinner, and hardener). Only used about 2/3 of the gallon with 3 coats. A buddy sprayed it in his garage. It has good gloss, but we'll see how long it holds up to the sun and tree branches. The paint was made by Limco - I can get the specifics if you're interested.

With all of this said, I still I am not as willing to run the truck down a tight trail as before I painted it even though that is why I bought it.