Pinion nut leaking

**transamgirl89** · 08-03-2011, 03:05 PM

So I took my car to the shop last week for an exhaust leak and my mechanic noticed I was slinging grease from the rear gear housing. He said it was a pinion nut seal and to replace it you have to take apart the housing and replace the seal and crush sleeve reseal the housing. I called my trusted shop in Alabama and he said you can just replace the seal without going and taking the whole thing apart. The shop here in GA that found it want roughly $600 to fix it when the shop in bama wants 340. Does that sound right or are they just trying to pull some shit?

**pajeff02** · 08-03-2011, 04:31 PM

A weeping pinion seal is a factory installed option on our cars. Many members have replaced theirs only to have them start weeping again soon after. I would clean off the underside of the car and then keep an eye on it to see how much is actually leaking. Unless it is dripping on the garage floor, I really would not worry about it. Don't forget to check the level in the rear and top it off if necessary.

**transamgirl89** · 08-03-2011, 04:50 PM

I'll definately try that first before I fork over more money.

**pajeff02** · 08-03-2011, 04:55 PM

BTW: Your trusted shop is correct -- no need to rip the thing apart. You drop the driveshaft at the rear and then with the back end in the air check the preload on your pinion bearing with an inch pound torque wrench. You also mark the nut and housing to ensure you get everything back right where it was. Remove the nut and pinion flange and then replace the seal. Assemble it exactly back to where it was and then snug the nut past that point until you achieve the exact preload you measured before disassembly. Sounds like he knows the drill though.

**transamgirl89** · 08-03-2011, 05:02 PM

yeah he used to own a performance shop. I trust him. I'm just gonna do like you said and scrub the grease off and see how much it leaks over a period of time.

**wileyCoyote** · 08-03-2011, 08:19 PM

pajeff is right, it's factory installed, but unfortunately was not an "option"... just look at how many pinion leak threads there are in this subforum right now!

mine leaks, has always leaked, has leaked only a few months after a diff rebuild, has leaked 12 months of the year - countless pinion seal replacements, and the damn thing will just go back to it's stable state: leak.

i'd just have your tech check the level every other oil change or so, ...other than that, you'll be chasing your tail and depleting your wallet to try and stop it..

**transamgirl89** · 08-06-2011, 08:58 PM

This is all the grease under the car.

289085_10150257331423644_570553643_7766956_646249_o.jpg

**pajeff02** · 08-07-2011, 01:22 PM

Doesn't look any worse than my last Ford truck underneath.

Is it dripping on the garage floor at all?

**Vexzer** · 08-07-2011, 06:47 PM

If the pinion shaft is damaged on the seal surface there is a sleeve you can repair it with. I had to do my 12-bolt after finding metal erosion on the shaft. Mine had shims so it was a matter of returning it to the original torque spec [no crush sleeve]. If your uses a crush sleeve, it is unlikely you can do yours without messing up the ring gear clearance.

**Ortiz11b** · 08-18-2011, 10:48 PM

Mine was leaking kinda bad... and then i started to hear a dragging sound... my pinion bearing went out causing the seal to start leaking badly... im rebuilding it right now.. and from doing my research i found a few videos showing you how to just change the seal

its a blazer but same process... save your self the $$$$$ and get some upgrades if possible..
good luck..

**wileyCoyote** · 08-19-2011, 06:34 AM

dominic, great video, thanks!

**My00Z28** · 08-19-2011, 08:58 AM

ha i replaced my seal about 3 months ago and now its leaking more than it was when i decided to replace it... its now leaking on to the floor my other seal just got my housing alittle wet... when i get around to replacing it again im going to a GM dealer and getting a GM pinion seal... its really not that bad to do but like that video shows i would never use an impact gun to tighten it down what i did was marked everything he did but counted the turns of the nut till it came off(mine was 10 full rotations), replaced seal, re-installed yoke, and counted the turns on the nut(10 full rotations) and added an extra 1/8 of a turn extra to preload the bearings with the crush sleeve... All of it done with hand tools is highly recommended IMO!!!!

**Cutlass** · 08-22-2011, 06:18 PM

I replaced my pinion seal with a GM seal...and it still leaks.

**35th-ANV-SS** · 08-22-2011, 06:28 PM

Isn't there two different seals? One is larger than the other? I swear I read this somewhere recently and if you use the wrong GM one that is what causes it to continue to leak.

**Firebirdjones** · 08-22-2011, 06:53 PM

I have had issues with some of the new seals not sealing properly. I actually had an issue with seals from GM and went to seals from Timken that seemed to work better.

There is a big problem with that video. Not only is the impact for reinstalling a bad idea but he forgot a major step. I guarantee he will have another leak within a couple hundred miles.

He didn't apply sealant to the splines before he slid the yoke back on. You will get seepage through the splines even if the seal is doing it's job. If you see a leak out of the pinion, take a close look and make sure the nut is dry. If it's actually coming out behind the seal, then it's the seal. But if you see the front of the yoke wet around the nut, then you have seepage coming through the splines and seeping past the nut and washer.
On reassembly it's important to use sealant (GM did) on the splines. I use 3M non hardening.

To get the preload correct on a rearend that is assembled, the nut needs to be reinstalled in it's original location and then I add about another 1/8th of an inch to keep pressure on the crush sleeve and therefore preload on the pinion bearings. If the sleeve on the yoke is worn, you can try sanding with 220 grit and then polishing it with emory cloth. This usually gets rid of most of the ridge. If it's really bad, either a repair sleeve or a new yoke is in order.

Also, using the inch pound wrench for rotational resistance only works when the pinion is the only thing in the rearend housing. That is how the pinion preload spec is given, new bearings are around 25-30 inch lbs. and used bearings are around 15-20 inch lbs. with the pinion by itself.

**wileyCoyote** · 08-23-2011, 07:02 AM

here's the thing... i've gone through the pinion seal replace dance numerous times - all $$$ down the drain... over the years, it's been three different shops, had it replaced at all of them, some more than once... even had it replaced w/in the parts warranty period a couple times, ...to the point shops are hesitant to even work on it.. so i didn't think to ask if the techs at these places were using sealant on the splines, but you'd think that i'd at least get lucky...

so, i blame the car, the design/GM, etc...

**Firebirdjones** · 08-23-2011, 08:01 AM

It's not the car or the design. There are literally 10's of millions of rearends out there, and they all share the same pinion design. They all don't leak.

If the repair is done properly with a good quality seal, it won't leak. Both of my 4th gens are bone dry, as a matter of fact, all of my cars pinion seals are bone dry.

If the seal repair is done with a worn yoke, then chances are good it will leak again unless you do what I described above, sanding the seal surface smooth, or buy a new yoke. Can't expect a seal to do it's job if the surface is worn with a groove, and most of them will have a groove if it's approaching 100,000 miles. Tossing a seal in there simply won't do it. Have to cover all the bases.

The other monkey wrench that causes problems are worn pinion bearings.

The sealant on the splines is a major step that I see most shops skip, or they just don't know. All factory assembled rearends from the manufacture had sealant on the splines.