Leaking Rear Diff

[Se77vN]

Ok, so I changed my rear diff lube like 2 months ago with amsoil, and a new gasket. Everything went fine, no leaks then about a week ago I notice a spot appeared on my driveway and soon enough several more appeared.

 

I got under my truck tonight expecting to have to tighten either the fill bolt or the bolts holding the cover on. What I saw was fluid that appeared to be leaking from where the drive shaft meets the diff...

 

Anyone ever seen this before? What does this mean? Can it be fixed?

 

Your help/input is greatly appreciated.

 

 

 

[the hammer]

Holy crap! That just started to happen on my truck today too! What the hell, you know? I need to know what to do also.

[remington351]

It's called a rear pinion seal. Others here will chime in on the replacement procedure, but it does involve things like crush sleeves and in/lb torque setting to get the pinion/ring gear contact surface correct. I'd advise heading to a shop to get it replaced. Good luck.

[the hammer]

I am gona check my overflow/air tube in the morning and see if it clogged. If not then i guess the pinion seal needs replaced.

[pm26]

I am gona check my overflow/air tube in the morning and see if it clogged. If not then i guess the pinion seal needs replaced.

 

How many miles on your truck? Now I have to check mine. Hopefully no leaks. Did GM start using cheap seals or what? These seals normally do not leak for many years. I had a lot of rear drive American cars in the past and never had a leak coming from the differential pinion seal.

[jblakeney]

This is not an armature repair. You need special tools to do this job. Mess it up and you will have to have the rear end rebuilt!!! It is the pinion seal as stated above.......

 

Jbo

[pm26]

I just checked mine - no indication of any leak.

[the hammer]

i have 78k on mine. i just had new ring and pinion installed 6 weeks ago and no leak. all of a sudden it started leaking this week.

[the hammer]

Yep. Seen Amsoil do that to a few seals.

 

is it because it is fully synthetic or what? I need to know, cause the shop i had work done put in Royal Purple gear oil. Is that the cause?

 

I used Amsoil before and no leaks, so I don't really know what to think about this situation.

[Se77vN]

Yep. Seen Amsoil do that to a few seals.

 

OH NOOOOOO.... wow... that's all I can say. I thought this stuff was supposed to be the best??

 

Anyways, thanks for all your quick replies. A couple of questions now:

 

1.) Can I just top it off for now until I can have it repaired? I may not be able to have the funds for this for like another month or so.

 

2.) what should I expect to pay for this?

 

**Edit... I have 169K miles on the truck

 

THX!

[the hammer]

dude, i think the first thing to do is check the fluid level, then the air tube. I just read about pinions leaking if overfilled, and mine didn't leak until this week. coincidentally, i added as much fluid as I could to the maximum amount allowed per GM recommendations. I am gonna let some out tomorrow and check my tube.

 

You may have overfilled it. Seems like your leak and mine are on about the same timeline in regard to synthetic fluid, fill, and weeks.

[pm26]

This is not an armature repair. You need special tools to do this job. Mess it up and you will have to have the rear end rebuilt!!! It is the pinion seal as stated above.......

 

Jbo

 

Armature repair?

 

Try amateur.

[Se77vN]

dude, i think the first thing to do is check the fluid level, then the air tube. I just read about pinions leaking if overfilled, and mine didn't leak until this week. coincidentally, i added as much fluid as I could to the maximum amount allowed per GM recommendations. I am gonna let some out tomorrow and check my tube.

 

You may have overfilled it. Seems like your leak and mine are on about the same timeline in regard to synthetic fluid, fill, and weeks.

 

How do you check the level? I don't have a fill hole in my cover, it's towards the back of the diff. And yeah I filled mine up to what GM called for, I think it was something like 3 or 3.5 qts??

[the hammer]

holy crap dude, i don't think it takes 3-3.5 quarts! that is A LOT. Usually 2 quarts puts you at the right level, not too high and not low.

 

You check the fluid level using allen wrenches in the fill hole (the fill plug you put a 3/8" drive in - the actual square part-, seen in your first pic above).

 

i think the highest level you want to see should touch the bent part of an allen wrench that is 5/8" down into the hole. The lowest is like 1 3/8" or more. I may be off on the exact number, but I do know if your fluid level is at 1" below that fill plug hole you are money on the fluid level.

 

someone here has to know the max and min level heights.

 

BTW, I added an aftermarket diff cover and it holds an extra 3/4 quart of fluid and I still did not get up to 3 quarts, so if you put that much in you got to let some out.

[Se77vN]

holy crap dude, i don't think it takes 3-3.5 quarts! that is A LOT. Usually 2 quarts puts you at the right level, not too high and not low.

 

You check the fluid level using allen wrenches in the fill hole (the fill plug you put a 3/8" drive in - the actual square part-, seen in your first pic above).

 

i think the highest level you want to see should touch the bent part of an allen wrench that is 5/8" down into the hole. The lowest is like 1 3/8" or more. I may be off on the exact number, but I do know if your fluid level is at 1" below that fill plug hole you are money on the fluid level.

 

someone here has to know the max and min level heights.

 

BTW, I added an aftermarket diff cover and it holds an extra 3/4 quart of fluid and I still did not get up to 3 quarts, so if you put that much in you got to let some out.

 

OK sorry I ordered 3 qts, and must have put them all or close too it. Maybe I overfilled it.