Rear Pinion Seal

[dpm6836]

I'm planning to change my diff. oil to Mobil 1. I noticed I have a slight leak (more of a seeping) from my pinion seal. I also have the same type of seeping from the diff. cover. I have a new gasket for the diff. cover.
How much am I looking at to have the pinion seal replaced? Is is possible my breather tube is clogged?

[tblazed]

My '02 had a seep at the pinion input shaft seal from day one, enough to cause oil residue to be on the sway bar beneath it. I changed the original GM "grape juice" oil to Royal Purple Max Gear 75W-90 a year ago, and the seepage stopped. Dry as a bone now. I would recommend you just try changing your oil first. 2002-'03 has a drain plug on the bottom of the dif housing, except you say the cover gasket is leaking too. BTW the GM factory oil that I took out had lots of finely powdered metallic particles suspended in it at only 12,000 miles.

[dpm6836]

Thanks.
I'll try that. If it keeps leaking I won't lose that much new oil. Then I'll have the pinion seal replaced.

[tblazed]

That's what I did... I changed the oil before taking it in to have them tear into the rear axle ass'y just to replace the seal. No guarantee the new seal would be any better. I gave myself plenty of time before the warranty ran out to make sure the seepage was stopped. Fortunately mine did stop seeping with just the oil change. Good Luck with it!

[MITZA]

Same as my situation, It looked as if the Diff gasket(cover) was leaking but was seepage from the pinion. I used the Mobil 1 hope that helps I'm out of warranty trucks at 27K miles. Damn shame should of stuck with my montero

[ScarabEpic22]

OK, on my 02 TB, the drain plug is underneath the diff in the center. The fill plug is on the passengers side . Use a 3/8" ratchet or similar and pull the fill first. Then pull the drain and drain old fluid. Install drain plug. Replace fluid with 2-3 qts. Amsoil (or Mobil 1) 75W-90 gear lube. Install fill plug. Drive truck and check for leaks, etc. Took me about 30-45min, and didnt bother to replace the seal, as I didnt even open it.

After I did this, my TB seems to have a lot less of the downshift clunk. Kinda weird, as I thought it was something to do with the tranny or the transfer case. :undecided

BTW, I have heard that not all GMT-360/370 trucks have the drain plug. Need to use a suction pump or something to get the fluid out, unless you want to pull the diff cover off.

EDIT: MITZA just edited their post, so this is kinda irrelevant now, but I will leave it here anyway.

[MITZA]

OK, on my 02 TB, the drain plug is underneath the diff in the center. The fill plug is on the passengers side . Use a 3/8" ratchet or similar and pull the fill first. Then pull the drain and drain old fluid. Install drain plug. Replace fluid with 2-3 qts. Amsoil (or Mobil 1) 75W-90 gear lube. Install fill plug. Drive truck and check for leaks, etc. Took me about 30-45min, and didnt bother to replace the seal, as I didnt even open it.

After I did this, my TB seems to have a lot less of the downshift clunk. Kinda weird, as I thought it was something to do with the tranny or the transfer case. :undecided

BTW, I have heard that not all GMT-360/370 trucks have the drain plug. Need to use a suction pump or something to get the fluid out, unless you want to pull the diff cover off.

EDIT: MITZA just edited their post, so this is kinda irrelevant now, but I will leave it here anyway.


I just performed the service tonight went like a charm I had the drain plug so I didn't have to remove the cover and used a modified gear oil pump to put the new stuff back in DAMN it looked nasty at 27K miles. Mobil 1 is not cheap like $9 per quart :) I hope this helps the seepage problem I never had any klunks.

[dpm6836]

I immediately ran into problems with this. Whoever had the TB before me damaged the square fill plug :mad: . I can't get enough force to loosen it. Luckily, I didn't drain it before I found this out. Got a new plug from a dealer and will have to drill the old one out and use an extractor kit. Fun, I hate it when simple things go down the crapper.

[tblazed]

A good tip I read elsewhere from someone that had a similar problem... always loosen the fill plug FIRST before draining or removing the diff cover, to make sure it's not damaged or seized. Very difficult to say the least putting oil back in if the fill plug is damaged or cross-threaded so bad that it won't come out!

[tblazed]

Here's a couple of pictures I took of my unofficial, unscientific test to see what would settle out of the OEM factory fill gear oil with less than 12,000 miles...

I put a sample of the oil in a plastic bottle. Then I laid ot over on a ring magnet overnight (first picture) , and you can see the results in the second picture.

http://users3.ev1.net/~epadget/tbgearoil3s.jpg


http://users3.ev1.net/~epadget/tbgearoil2.jpg

[MITZA]

Nasty mine was about that looking bad at 33K. You'd think they would use better gear oil from the start and not put such long intervals in the owners manual to change stuff. By the time most people reach em the gears and bearing are shot or have tons of slop in them.


BTW anyone know what we can use in the T-case instead of the GM stuff? what weight and quantity ?

-Just did the front diff today 9-25-05 man that was easy :)))

[ScarabEpic22]

Mine were pretty bad at 50k too. I changed the front and rear diffs with Amsoil Severe Gear (for towing) 75W-90. Much smoother now. Also, as of now, there is no replacement fluid for the AutoTrak II fluid for the transfer case. I spoke to Amsoil, and they said they are working on a replacement, but didnt have any more info. So, if you change the transfer case, put the gm fluid back in because nothing else will work properly.

[tblazed]

Did u change the front Diff also? 2WD here.

It's not the quality of the original GM gear oil, it's the particles of metal that wear off during the first few thousand miles break-in that you see. The oil is doing its job keeping all that powdered metal in suspension. If you look closely at the picture you will see a silver gray metallic sheen in the ring of "stuff" that settled out. That's why I changed it at 12k miles - to get the break in wear particles out of the dif. Lucky for me the oil change to Royal Purple 75W-90 completely stopped the seep at the seal too.

[MITZA]

Mine were pretty bad at 50k too. I changed the front and rear diffs with Amsoil Severe Gear (for towing) 75W-90. Much smoother now. Also, as of now, there is no replacement fluid for the AutoTrak II fluid for the transfer case. I spoke to Amsoil, and they said they are working on a replacement, but didnt have any more info. So, if you change the transfer case, put the gm fluid back in because nothing else will work properly.


Any idea on how many Quarts of the AutoTrak is required ?

[ScarabEpic22]

It says 2 qts, I actually put in about 2qts, but they come in 1L bottles, so you will have a little left over.

[MITZA]

It says 2 qts, I actually put in about 2qts, but they come in 1L bottles, so you will have a little left over.


Thanks, I appreciate the info. :)