Rear end pinion seal

**Fastcar** · 01-20-2008, 09:49 AM

My T/A just turned 100K and the pinion seal is leaking again! I had it replaced at 54K by the Pontiac dealer, stock rear, A4. Should the seal last longer than 46K or is this GM's way of ensuring that you'll have to replace the rear when it locks up due to lack of lubrication? I've learned the hard way that quick lube places that say they check all the fluids - DON'T! Yeah, I know this is a problem that comes with GM products - look at the recent Caddy and Pontiac recalls for leaking pinion seals. I guess GM still hasn't figured out how to seal the rear end properly after all these years. I never had this problem with any other vehicle I've owned. What gives (besides the rear)?

**sunsetorangess** · 01-21-2008, 06:28 PM

Its a simple seal to replace, Could be a iffy seal but since it lasted so long it could be that something got caught up in there and just tore up the seal. I had an old truck, when i went though the corn fields back home, the brush would tear it up everytime.
J

**Ten5TireRacer** · 01-22-2008, 07:00 PM

How is GM making money from it when the seal lasted well past your warranty?
The differentials in the little gokarts they are recalling is a completely different design than what is under a conventional rear drive vehicle, so you can't really compare them together.

**Fastcar** · 01-23-2008, 06:55 AM

Originally Posted by Ten5TireRacer

How is GM making money from it when the seal lasted well past your warranty?
The differentials in the little gokarts they are recalling is a completely different design than what is under a conventional rear drive vehicle, so you can't really compare them together.

No. I bought my car used, 3 years old with no warrantee that I knew about. One of the first things that I had to do was have the pinion seal replaced with the mileage @ 54K. Now at 100K the seal needs to be replaced AGAIN. Do the pinion seals last only some 40K miles?

**Ten5TireRacer** · 01-23-2008, 03:04 PM

Some times they do, sometimes they don't. There could be any number of things that caused/is causing it to leak. It's the same as brakes wearing out. I couldn't make it more than 25,000 miles with my Z28, but have exceeded 50,000 miles with my dually that spends most of it's time pulling a trailer. Unfortunately there is really no explenation for any of it?

**2001NBMZ28** · 01-23-2008, 03:51 PM

Mine leaks a little, no drops in the driveway yet so I don't worry about it.

**Wesman** · 01-23-2008, 04:02 PM

Originally Posted by Fastcar

No. I bought my car used, 3 years old with no warrantee that I knew about. One of the first things that I had to do was have the pinion seal replaced with the mileage @ 54K. Now at 100K the seal needs to be replaced AGAIN. Do the pinion seals last only some 40K miles?

Sounds like something else is causing the issue. Did you check the pinion bearings themselves?? If they are starting to go bad, and there is even the slightest amount of play, it will cause the pinion seal to leak. Also, the transmission mount and rear suspension bushings have a lot to do with the pinion seal leaking. If the trans mount is bad or very worn out, it will change the pinion angle everytime you hit the throttle, which will ruin the seal rather quickly. Same goes for the rear suspension bushings on the trailing arms and panhard rod, if they are worn out the rear will constantly be shifting position, which will ruin the seal as well.

**01ws6er** · 01-23-2008, 05:45 PM

Originally Posted by Wesman

Sounds like something else is causing the issue. Did you check the pinion bearings themselves?? If they are starting to go bad, and there is even the slightest amount of play, it will cause the pinion seal to leak. Also, the transmission mount and rear suspension bushings have a lot to do with the pinion seal leaking. If the trans mount is bad or very worn out, it will change the pinion angle everytime you hit the throttle, which will ruin the seal rather quickly. Same goes for the rear suspension bushings on the trailing arms and panhard rod, if they are worn out the rear will constantly be shifting position, which will ruin the seal as well.

My rear suspension has just started squeeking like hell as well, and I can't quite pinpoint an exact part, but I think it is my drivers side (rear) control arm that is making the noise. I can actualy move it side to side, so maybe its time to replace. And with the tranny mount thing, does the same apply whether m6 or a4?

I almost forgot, my pinion bearing is starting to whine!! Anyone know how much that shit costs to replace??? I'm not leaking any fluid, but I want to get it fixed soon! Thanks.

**Ten5TireRacer** · 01-23-2008, 08:08 PM

Originally Posted by Wesman

Sounds like something else is causing the issue. Did you check the pinion bearings themselves?? If they are starting to go bad, and there is even the slightest amount of play, it will cause the pinion seal to leak. Also, the transmission mount and rear suspension bushings have a lot to do with the pinion seal leaking. If the trans mount is bad or very worn out, it will change the pinion angle everytime you hit the throttle, which will ruin the seal rather quickly. Same goes for the rear suspension bushings on the trailing arms and panhard rod, if they are worn out the rear will constantly be shifting position, which will ruin the seal as well.

The trans mount has nothing to do with the pinion seal leaking. If the trans moves up and down, or even side to side it's not going to effect the pinion in any way shape, or form. It will effect the u-joints, but that's their job to creat different angles, and the slip joint makes the shaft longer or shorted depending on suspension travel.

**Wesman** · 01-23-2008, 08:53 PM

Originally Posted by Ten5TireRacer

The trans mount has nothing to do with the pinion seal leaking. If the trans moves up and down, or even side to side it's not going to effect the pinion in any way shape, or form. It will effect the u-joints, but that's their job to creat different angles, and the slip joint makes the shaft longer or shorted depending on suspension travel.

My transmission mount was broken in half when I bought my car. As the trans jumps up and down/side to side, it puts stress on the pinions yoke, regardless of the u-joints flexing. Pinion seal went bad shorty thereafter.

A bad trans mount can definitely cause a bad pinion seal.

**Ten5TireRacer** · 01-24-2008, 04:21 PM

You can believe what you want, but you even said shortly after it leaked. Why didn't it immediately leak? You are contradicting yourself with that statement. It had nothing to do with a trans mount. If you can get the yoke to move the pinion gear in any direction you've got bigger problems than just a seal leak!

**Firebirdjones** · 01-24-2008, 05:15 PM

Originally Posted by Fastcar

My T/A just turned 100K and the pinion seal is leaking again! I had it replaced at 54K by the Pontiac dealer, stock rear, A4. Should the seal last longer than 46K or is this GM's way of ensuring that you'll have to replace the rear when it locks up due to lack of lubrication? I've learned the hard way that quick lube places that say they check all the fluids - DON'T! Yeah, I know this is a problem that comes with GM products - look at the recent Caddy and Pontiac recalls for leaking pinion seals. I guess GM still hasn't figured out how to seal the rear end properly after all these years. I never had this problem with any other vehicle I've owned. What gives (besides the rear)?

When checking the rear pinion also,,,also look closely at the pinion nut. When replacing the seal,,,it's important to clean the threads of the nut and the pinion gear as well,,,and sealant needs to be applied here.

The seal can do it's job but it's also possible for gear oil to seep through the threads and come out around the nut.

If it's wet around and behind the dust cover (seal protector) Then it's probably the seal. If it's wet in front of the dust cover and around the nut,,,then it's probably seeping through the threads.

Sometimes flat rate mechanics ( like GM) may not take the time to clean the threads and apply sealant, they simply install new seal and reassemble.

Before you take anything apart,,,,grab the yoke and see if you can move it at all,,,up and down or side to side.....if it's loose at all the seal cannot do it's job,,,which means either GM didn't tighten the nut enough,,,,or the pinion bearing is on it's way out. It's criticle when doing a pinion seal to make sure you have proper preload on the pinion bearing on reassembly.

**Fastcar** · 01-25-2008, 10:50 PM

Thanks to all of you for your help! I guess this time I'll have to go to a better mechanic that will take the time to do the job right. I'll give him a printout of all the replies so that he can check out all of the possible causes.