Uh Oh - A leak!

[01Y87]

Yesterday I was down on the ground using clay to get some crap off the bottom part of the rear bumper cover when i happened to notice under the car that my differential housing/axle was COVERED with thick gooey axle grease!!! Ugghh All over the bottom of it and some on the rear cover lower part also. I tried to spray it with degreaser and hose it off and it didn't even all come off.

I need to drive it up the ramps so i can get further under it but I'm thinking its the front oil seal since the airflow would push it back over the case. Is that a labor-intensive job? How expensive would that be? Has anyone else ever had this type of leak, is it common on the f-body? It has been about 50k mi since the case was last opened to change the fluid.

[M3EATER - GG '00 WS6 T/A]

Bruce,

Yes, it does sound like your pinion seal (input seal) is leaking. This is fairly common, especially if the car is road raced or driven in a way that really heats up the differential.

To replace the seal, you have to:

1) Disconnect the driveshaft rear u-joint from the pinion yoke.

2) Remove the pinion nut.
NOTE: it is technically not permissible to remove the pinion nut and re-install it without replacing the crush sleeve on the pinion gear, which requires complete dissassembly of the differential. However, it is generally acceptable to remove and replace the nut if you first mark the position of the nut to the threaded end of the pinion. More on this later...

3) Pull the pinion yoke off of the pinion gear splines.

4) Pry out the old seal.

5) Clean-up/polish the pollished surface of the yoke, where the seal runs... with some 600 grit emery paper.
NOTE: If there's a fairy heavy groove in the yoke, where the seal runs.... you may not be able to polish it. The yoke may have to be replaced. The groove will just cause the new seal to fail.

6) Lubricate the lip of the seal with some grease or oil ... add a bit to the polish surface on the yoke.

7) Install the yoke over the pinion splines.

8) Apply some lock-tite to the threads of the pinion nut and install it.

9) Tighten the nut until the marks that you made line up.

10) Install the drive shaft u-joint to the yoke.

Have fun!

Gordon

[01Y87]

So if I took it into a GM dealer they would probably want to take apart the whole thing??? Geez.....that's a lot of labor!!!!

[M3EATER - GG '00 WS6 T/A]

Some dealers will do it the quicky way... you'd have to check.

Why don't you find a reliable independant shop anyway? Dealer would be my last choice.

Gordon

[01Y87]

Yeah, I may do that.

[Joe 1320]

There is an important step often overlooked which makes a differance in the life of the rest of the componants. Use a torque wrench on the large pinion nut and record the effort required to turn the pinion. Marking the pinion sometimes is not quite close enough. When reassembling, gradually tighten the pinion nut and check the rotating resistance. Keep tightening until the resistance is equal to the torque reading before disassembly. Overtightening of the pinion nut and collapse of the crush sleeve is the major source of repeated problems after changing a pinion seal. Hopefully, the torque reading will be dead on when your marks are realigned. If not, I would go with the torque reading rather than the mark. BTW, A solid spacer is often substituted in place of the crush sleeve to help alleviate crush sleeve woes.

To clean up the existing mess, put the car up on ramps or stands. Wear eye protection, spray everything down with simple green and start brushing with a stiff brush. It will take several applications and rinse cycles, but eventually it will be clean.

[M3EATER - GG '00 WS6 T/A]

Thanks Joe....

I forgot about the initial torque reading.

[01Y87]

Does regular engine degreaser not work on this type of grease? Just curious why Simple Green.

[Joe 1320]

Simple green is non toxic and biodegradeable.

[fastTa]

Does regular engine degreaser not work on this type of grease? Just curious why Simple Green.

If you want a good strong engine degreaser, try the Zep degreaser. Or you can always use good ole B-12 Chemtool carbureter cleaner. Works everytime on tough thick grease.

Also, when I did the 4.56 gears in my Tahoe, I bought a new bearing kit from Auto Zone. It replaces all the bearings in the differential such as front/rear pinion bearing, carrier bearing. And it was only $79.95 for my factory 12-bolt. I would imagine it might be a little cheaper for your 10-bolt.

Just a though while your there.

[Kevin - Blown 95 TA]

There is an important step often overlooked which makes a differance in the life of the rest of the componants. Use a torque wrench on the large pinion nut and record the effort required to turn the pinion. Marking the pinion sometimes is not quite close enough. When reassembling, gradually tighten the pinion nut and check the rotating resistance. Keep tightening until the resistance is equal to the torque reading before disassembly. Overtightening of the pinion nut and collapse of the crush sleeve is the major source of repeated problems after changing a pinion seal. Hopefully, the torque reading will be dead on when your marks are realigned. If not, I would go with the torque reading rather than the mark. BTW, A solid spacer is often substituted in place of the crush sleeve to help alleviate crush sleeve woes.

To clean up the existing mess, put the car up on ramps or stands. Wear eye protection, spray everything down with simple green and start brushing with a stiff brush. It will take several applications and rinse cycles, but eventually it will be clean.

If you do this, you might have to pull off the brakes to get a good reading, otherwise there's going to be a lot of uneven drag. I don't think you're even supposed to have the axles in, but it's been quite a while since I've done it, and if you're just trying to match torque before disassembly, then you might be OK with the axles in there - you might just be heavier than the 15-20 lb/in than they give you for broken-in bearings. You also have to have a recording torque wrench in the inch-pound range which costs about $75.

[M3EATER - GG '00 WS6 T/A]

if you're just trying to match torque before disassembly, then you might be OK with the axles in there - .

Yes, Kevin, when doing this you're just getting a reletive reading to go back to when you re tighten the nut.

[Kevin - Blown 95 TA]

Yes, Kevin, when doing this you're just getting a reletive reading to go back to when you re tighten the nut.

The point of what I was trying to say is that I don't think I would do it with the wheels & brakes on. That 15 lb in would get lost in the overall torque (which would be a lot more) and you wouldn't know where you were on the pinion bearing measurement, especially if the pads are scraping on the rotors. a lot of guys, including mechanics & dealers, have trouble getting this right and end up lunching the bearings & gears. Some just luck out and nail it without any fancy torque wrench at all. They ought to just make the seal better so noone has to go through this for a 6 dollar part. BTW, I'm a believer in the solid spacer. That is harder to set up initially, but you don't have to worry about re-crushing it and having it collapse under a hard load.