Differential Pinion Seal Leak - Options?

S_Mazza

Registered User
Hello all. While replacing my fuel pump, I realized that I have differential fluid leaking from the pinion area. It is getting slung up onto the floorpan. I assume that this means I have a leaky pinion seal.

I am not sure how easy it is to replace a pinion seal. Is it possible to do this with the differential in the car (remove the driveshaft?) What tools would I need? And are there any other parts required besides the pinion seal itself?

If I do that, should I replace U-joints at the same time?

If it is not possible to do this in the car, then should I rebuild the Trac-Lok at the same time? I mean, I don't want to pull this thing again in a year. Or maybe it's easier to buy a new Trac-Lok unit?

Than you for any advice you may have ...
 
I am not sure. I will try to check this weekend, and refill if it is low. I haven't noticed a lot of gear noise, but there is a little noticeable at low speeds.
 
You can also check for slack between the pinion & ring gear by hand, which is a cheap way of gathering more info short of tearing things down. Be sure to push/pull up/down on the flange to check the input bearing as well.
 
I assume that I would put the transmission in Neutral, then try to rotate the pinion flange and driveshaft by hand and check for play?
 
I assume that I would put the transmission in Neutral, then try to rotate the pinion flange and driveshaft by hand and check for play?

Actually, in gear with the parking brake on, first, to check lash & input bearing side/side~up/down, then neutral & no brake (wheel/s spinning forward) to check for binding. Don't misinterpret any locking diff involvement.

This can be a case where if you don't think you've uncovered something, there are perhaps no conclusions to be made. Only if something chronic, such as excessive lash/bearing play, binding, grinding, bumping, jumping, moaning, burping...well, you get the idea - only if something grabs your attention will you know you need to go further. This doesn't mean if you don't find anything at this point that all is well.

These are simply easy enough to do that you've got little to lose and maybe some info to gain. Some people would go straight to a tear down - each his own style, of course.
 
Well, I checked the differential out last night after the pavement dried out.

I tried pushing the pinion/companion flange up/down, side/side. It seemed to be tight, with no play at all. So I guess the pinion bearing is still good.

With both rear wheels in the air and the emergency brake off, the wheels spin together in the same direction. (I didn't go to the extent of putting one wheel down and measuring the torque before slippage occurs.) So I think the traction locking is still good.

Now, back under the car, I tried to rotate the driveshaft. I didn't detect any play at the differential or the u-joints. (I'm actually a little surprised, because I think the U-joints are original.) It seemed like everything would rotate smoothly for a little bit, then came up against something in the transmission and stopped. There was a clanking noise that seemed to come from inside the transmission. Is that normal?

Also, I popped the drain plug and tried to swap the gear fluid. I now know that gear lube does not siphon easily at 38 degrees Farenheit. It's like molasses. Anyway, since that wasn't happening, I just checked the level and took a small sample of the fluid. The fluid was a light tan or brown color. It looked clear and didn't smell especially bad. That seems like a good sign, right? It only took a little bit of fluid to get the level back up to the bottom of the fill hole.

So, all in all, what do you think? Does the diff sound like it's in good shape?
 
>So, all in all, what do you think? Does the diff sound like it's in good shape?

Except for throwing oil out the pinion, yes.
 
Except for throwing oil out the pinion, yes.

Well, yes. There is that. :rolleyes:

Seriously, though - Thanks for the feedback. I am not a differential guru, and the info is helpful.

I think I am going to just check the level occasionally for now. I can't get into it too much over the winter. I may build up an aluminum pumpkin and keep it in reserve until the rear suspension gets a going-over (think Spring).
 
Good luck with it - if you get around to topping it off, don't forget to use proper fluid for your locking diff.
 
Good luck with it - if you get around to topping it off, don't forget to use proper fluid for your locking diff.

What is the proper fluid for the dif?? I need some desperately after i replace the seal and i don't know if the shop i take it to for that is putting the correct stuff in it...seems like the viscosity was just too thin for how long it stayed in, either that or the seal is VERY gone lol any help would be awesome, thanks!!
 
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