Transmission Tail Shaft Seal

Scoutr2 · June 16, 2011

Hello all. I'm new to this website and did a search on this topic, but couldn't find anything that hit on it. My problem has been with a slight dripping of transmission oil from a leaky tranny tail shaft seal. I bought my 2007 Classic 2500HD Crew Cab new, in December, 2006, so I still have some warranty left (39K miles). I have had this tail shaft seal replaced twice since I've owned the truck (at 18K and 37K miles). Last time, I asked that the tech check the shaft and the bore in the tranny case to see if a defect there might be causing the seal to fail prematurely (I hope they are designed to last more than 16K-17K miles!!!) The answer I got was that there did not appear to be any problems with those mating parts.

I have had this same problem with tail shaft seals in previous GM vehicles I've owned, as well - specifically with my 2003 1500 Suburban and my 1999 1500 Suburban.

I tow a 30' travel trailer (about 8000 lbs) with this truck, but only towed popup campers with the Suburbans.

Has anyone else had problems along these lines? If so, did you discover any underlying cause for the seal failures? Or is this just an example of putting in the cheapest seal they can buy? (I know that all manufacturers are always looking for the lowest cost supplier, but those parts should meet or exceed GM's minimum specs.)

This seems to be a problem that GM doesn't think is too important to fix - like the intermediate steering shaft problems that they have had in ALL GM vehicles for over a decade. I cannot believe that fixing things repeatedly, by the thousands, is cheaper than spending an extra buck or two per vehicle, to avoid the problem to begin with!

Mike

az'03Silverado · June 16, 2011

Welcome to the forum. Just a couple of thoughts. Do you park on a steep driveway? Is the fluid level in the trans correct? I've only had my trans seal leak once and that was when my truck was put up on a roll-off tow truck and the steep angle caused fluid to migrate back toward the seal and leak, but the leak went away.

Scoutr2 · June 17, 2011

Welcome to the forum. Just a couple of thoughts. Do you park on a steep driveway? Is the fluid level in the trans correct? I've only had my trans seal leak once and that was when my truck was put up on a roll-off tow truck and the steep angle caused fluid to migrate back toward the seal and leak, but the leak went away.

I park in my garage at night and my driveway only falls 2" over 42'. The parking lots at work are all level. I am a Service Training instructor for a major heavy equip manufacturer, so I am always checking fluid levels, etc. I have 4WD, but only use it in snow, or when pulling in and out of grassy/soft campsites. (Too easy to spin, when moving 4 tons of travel trailer.) Rear end axle ratio is 4:10 and I have the HD 4-speed auto transmission, with large capacity cooler. Never overheated the transmission or the cooling system.

So I'm puzzled as to why I've been having these problems. Perhaps it's just coincidence, but seems unlikely I'd get 3 in a row!

Mike

nickvrebel · June 17, 2011

just a few thoughts, not trying to insult you, but throwing this out there:

*you are referring to a 4wd, the seal on the tailshaft is off of the transfer case, not the transmission. Have you looked at the transfer case fluid level? while on a level surface you can remove the driveshaft without leaking fluid, therefore the seal should not leak while the vehicle is parked, residual from while driving of course would be different. Refer to the owner's manual for proper methods for checking fluid levels. The transmission must be warm, engine running, etc.

*I'm surprised that you had multiple trucks do this. The transmissions and transfer cases for the 1500 series and HD series is different - including the yoke on the driveshaft. I've never seen one leak (I've been under several trucks with high miles) except for a specific reason. Sounds like you have some bad luck.

Personally considering it's still under warranty I would take it to another dealer to have the output shaft and housing/ seal mating surface/ driveshaft yoke inspected for burs or being out of round. Having the driveshaft checked for balance is another thing that would be prudent (at higher speeds if out of balance it would cause a wobble). If it happens again I would contact GM Customer Service and advise them of the ongoing problem and request assistance. They seem to be responsive enough to get an expert (and/or engineer) to come out and take a look at it.

Another route, which I would save for a last resort: On my girlfriend's Audi the dealer could not correct a popping sound the vehicle made when in reverse with the wheel turned (backing from a driveway). After several failed repair attempts at the dealer she brought the car to an independent shop. The shop diagnosed it as lose bolts on the subframe and an improperly installed motor mount (the dealer service center changed all motor mounts a few months prior and both CV shafts a few months prior to the motor mounts). The shop corrected the issue for under $75 and my girlfriend presented the service ticket to the service manager at the dealer who apologized and reimbursed the cost. She is satisfied with the repair but her beloved A6 will not be replaced with another Audi due to poor mechanic performance.

Good luck

Scoutr2 · June 17, 2011

just a few thoughts, not trying to insult you, but throwing this out there:

*you are referring to a 4wd, the seal on the tailshaft is off of the transfer case, not the transmission. Have you looked at the transfer case fluid level? while on a level surface you can remove the driveshaft without leaking fluid, therefore the seal should not leak while the vehicle is parked, residual from while driving of course would be different. Refer to the owner's manual for proper methods for checking fluid levels. The transmission must be warm, engine running, etc.

*I'm surprised that you had multiple trucks do this. The transmissions and transfer cases for the 1500 series and HD series is different - including the yoke on the driveshaft. I've never seen one leak (I've been under several trucks with high miles) except for a specific reason. Sounds like you have some bad luck.

Personally considering it's still under warranty I would take it to another dealer to have the output shaft and housing/ seal mating surface/ driveshaft yoke inspected for burs or being out of round. Having the driveshaft checked for balance is another thing that would be prudent (at higher speeds if out of balance it would cause a wobble). If it happens again I would contact GM Customer Service and advise them of the ongoing problem and request assistance. They seem to be responsive enough to get an expert (and/or engineer) to come out and take a look at it.

Another route, which I would save for a last resort: On my girlfriend's Audi the dealer could not correct a popping sound the vehicle made when in reverse with the wheel turned (backing from a driveway). After several failed repair attempts at the dealer she brought the car to an independent shop. The shop diagnosed it as lose bolts on the subframe and an improperly installed motor mount (the dealer service center changed all motor mounts a few months prior and both CV shafts a few months prior to the motor mounts). The shop corrected the issue for under $75 and my girlfriend presented the service ticket to the service manager at the dealer who apologized and reimbursed the cost. She is satisfied with the repair but her beloved A6 will not be replaced with another Audi due to poor mechanic performance.

Good luck

Some good points here. I may take a look at the transfer case fluid level. But I think it will probably check OK, because the dealership just replaced the (2nd) tail shaft seal about 1500 miles ago. I asked them to take a look at roundness, nicks or burrs on the shaft and the seal counterbore in the case. They said it all checked out OK. I asked about the drive shaft being bent or out of balance, but they told me that if it was out of balance or bent enough to cause 2 seals to fail, I'd surely be able to detect vibration during certain speeds - depending on how bad it was. Sounds sensible, but it could be slightly out of balance or bent and I have no way to check it myself.

GM has always been good about fixing things past the warranty, if there is a paper trail that shows attempts to correct the problem prior to the warranty expiring. At the very least, I can just keep taking it back until they get it corrected.

But it is still puzzling why I've had this issue with three vehicles. Other than this one problem, I've had no complaints about the truck. It has been trouble free since the day I bought it!

Mike

Typicalid10t · February 8, 2012

I myself have a 2003 z71 Sierra and I just noticed a bit of residual transfercase fluid around the yoke. I inspected the it a little closer and the seal on the transfercase is brittle and cracked. Is this serious? The residual fluids were def splattered while driving, not enough to stain the driveway though. Im def gonna check fluids tomorrow just to be safe.