Pinion Seal

[c3po]

I recently had a Mechanic who works out of his garage at his house replace the Pinion Seal on my Differential. I have the GM 7.5 Differential and it has 381,000 miles on it.

It started leaking again, so I checked the Vent Plug, and it had a little bit of junk so I popped it off and cleaned it out, but I am still having leaks.

My Mechanic told me the Driveshaft yoke was fine, I got the Pinion Seal from CarQuest and I spent about $12.00 for it. The Mechanic now wants me to get a GM Seal from the Dealer which goes for about $26.00

He thinks the CarQuest Pinion Seal could be a " Made In China " knockoff.

The U-Joints are only 2 years old and I do keep them greased, so they are fine.

I think I have ruled out the Pinion Bearing since the Rearend is not making any noises, meaning like any kind of groaning noises.

One member who I Pmed on here thought it might be good to go back to a Dino Gear Oil, I currently have Amsoil Severe Gear 75W-90 in the Differential. He thought a synthetic gear oil would leak more.

The mechanic who worked on my car has about 30 years of experience.

I would hate to spend $26.00 on a new seal plus his labor charge of $50.00 and still have a leak.

I priced a driveshaft yoke from Denny's Driveshaft for about $75.00

Any info or comments would be appreciated.

The leak is coming from the bottom of the Pinion Seal.

 

[Kestas]

I took a class on seal design and forensic analysis, and just spent the past two days looking at a couple seals for defects. There are a multitude of reasons why a fresh replacement seal can leak. Let me think of a few.

- seal was damaged during installation
- seal is defective, i.e., molding defect, tear, nick, missing garter spring, etc.
- seal was installed crooked
- LH seal inadvertently installed for RH application
- seal installed backwards
- wrong seal (wrong application)
- nick in shaft
- excessive wear groove on shaft
- lead-in grind angle on shaft is wrong

Much of this will require close examination of the seal to determine what went wrong.

 

[Trav]

Question: Is the leak at the rubber part of the seal or coming out of where the metal part of the seal is pressed into the housing.

If its coming out of the metal part the mechanic is 100% at fault,he probably used no sealer around the metal before putting it in.
I usually use a little indian head gasket shellac on these parts.

If its leaking at the rubber,the yoke make be worn or he may have nicked it.In either case i don't believe car quest seals are any worse than OEM they are only relabeled brand names.

IMO he should redo the job on his dime minus the part.
A good mechanic knows a worn yoke and should have informed you if this was the case,he should have been looking for the reason the seal failed in the first place.He messed up.

 

[c3po]

Originally Posted By: Trav
Question: Is the leak at the rubber part of the seal or coming out of where the metal part of the seal is pressed into the housing.


It is coming out of the Rubber Part, and he did use some sealer, I was watching him.

Quote:
If it is leaking at the rubber, the yoke may be worn or he may have nicked it.


He did say that the Yoke was not bad, but maybe slightly worn, 381,000 miles, come on its got to be worn.

Quote:
In either case I don't believe carquest seals are any worse than OEM they are only relabled brand names.


I just got off the phone with my dad's friend from childhood who has been messing with cars since 1955 and he was a UPS mechanic for over 35 years, he said the same thing, the CarQuest part will be the same as the ZOEM part, just a different package.

He thinks I need to get a Yoke Kit that has some kind of sleeve, he said the sleeve slides on the Rear pinion and I could have a slight groove worn in the Diff Yoke.

The only other option if I cannot get a Sleeve Kit is to get a new Yoke, if that's the case, where do I get a Driveshaft Yoke.

 

[demarpaint]

Originally Posted By: c3po


The only other option if I cannot get a Sleeve Kit is to get a new Yoke, if that's the case, where do I get a Driveshaft Yoke.


Google DTS Drive Train Specialists IIRC, they might have it. If not your local friendly Chevy dealer will probably have to order it for you. At this point with 380+K miles I'd think it has some wear and I would just bite the bullet and get the parts and be done with it. Not worth the risk of doing the job a third time. JMO

 

[Herz]

Have it measured and toss a Speedi Sleeve on it if it is worn. May have to take it to a machine shop to get lathed to the right diameter. I use the cheap Kragen oil seals and they work fine.

 

[Trav]

last time i got a pinion yoke sleeve it was from NAPA,they also use them for front crankshaft seals.Approx $40 and they use the stock seal.Yes at 300+k it is worn for sure.

Installation tip: put the new sleeve on top of a 75-100w incandescent bulb for 30 min before grabbing it with pliers to drop it on.Work quickly and it will fall on with very little use of the mallet,when it cools it will be tight as a drum.

http://www.vsm.skf.com/en-US/HeavyDuty/KitsAndTools/SpeediSleeve.aspx

 

[c3po]

I just talked with my Service Advisor Buddy over at Chevrolet after I got a ridiculous price on a driveshaft yoke from there service department.

He has a 1998 Pontiac Firebird and he has the same problem, he has tried different Pinion Seals and he even replaced the Driveshaft yoke and still had a leak, he even took the differential apart and could not find anything that would be causing the leak, meaning the diff parts showed no wear.

He thinks this is a manufacturing defect or that GM just cut some corners, he also thinks that my problem could be some wear in the actual differential itself, he thinks I will be wasting money trying to do anything, he said since the Diff is not making any noise that I should just keep an eye on the Diff Level and just live with it.

He told me that my mechanic would have been able to tell if there was a groove in my driveshaft yoke, guess I will keep open minded and see what other members have to say.

I can also call my mechanic and ask him about putting in that sleeve kit, maybe there is wear that he cannot see with his eyes.

 

[demarpaint]

I doubt it is a defect if the rear made it to 380+K miles and just started leaking. I'd say wear, it could also be time to look for another mechanic for this job.

 

[40Deluxe]

Agree w/your dad's friend.The old seal has probably cut a groove where it ran,the new seal will not seal in that groove.The part you need is called a readi- sleeve and installs easily on the yoke and gives the seal a new surface to run on.I have installed many of these and they work very well.I will always put one on the crankshaft seal surface if it is even remotely worn.

 

[Steve S]

Originally Posted By: 40Deluxe
Agree w/your dad's friend.The old seal has probably cut a groove where it ran,the new seal will not seal in that groove.The part you need is called a readi- sleeve and installs easily on the yoke and gives the seal a new surface to run on.I have installed many of these and they work very well.I will always put one on the crankshaft seal surface if it is even remotely worn.
+1 on the redi sleeve ,well worth the cost, and check the runout on the pinion shaft to see it there is a worn bearing.

 

[mechtech2]

A Speedi-Sleeve or similar product should fix this.
It is a thin sleeve that goes over the old yoke wear area, and a new seal with it. You can't use the factory seal.
These take care to install right. They have to be straight and perfect. Easy to screw up.

And note how your mechanic tightens your pinion nut . This is the crush washer setting. You can't just tighten it. I usually make a mark on the nut and shaft, and tighten it back to there - only!
A loose bearing preload can cause leakage with otherwise good sealing parts.
Who knows where you are at now, though.

A guy who has decades of experience may have wrong ideas - kinda like a guy who has a bad golf swing for years - you perpetuate the bad ideas! Years in maintenance of singular vehicles is not a proof to me of skills. I have known lame mechanics who worked for years at such jobs.

 

[onion]

There are several possibilities here. One thing I'd be interested to know is this: Does that car have a manual transmission? Yes, I know we're talking about the yoke on the rear diff., not the transmission,

 

[c3po]

Originally Posted By: onion
There are several possibilities here. One thing I'd be interested to know is this: Does that car have a manual transmission? Yes, I know we're talking about the yoke on the rear diff., not the transmission,


This car has an Automatic Transmission.

I am going to pickup the Sleeve Kit tommorow and my mechanic is going to put it in for free since the problem really was not the Pinion Seal.

 

[onion]

Well that shoots down one idea- I have seen where the splines become loose on high mileage vehicles with manual transmissions, due to the jerking around and such- compared with an automatic.

My guess is that he either damaged the seal on installation, or didn't properly tighten the pinion nut. To do this job properly, you technically need a new crush sleeve and you need to remove the axles and differential to properly set the rolling torque of the pinion bearings. Mechtech's method will generally work, but like he said- nobody knows what the crush/preload is at this point, now that the thing has been apart and is leaking.

I think the Speedi Sleeve is a good idea, just in case. And once it's back together... with that many miles, I wouldn't mess with it again unless the leak is really a problem. Or unless you're willing to pay to have the job done right, which will require a new crush sleeve, pulling the axles and diff, and properly setting the bearing preload.

 

[mechtech2]

At least mention about the preload to the mechanic, so he knows you are aware of it.
Ask him specifically how he maintained the old setting.

 

[c3po]

Well, the speedi sleeve is on there and so far I do not see any leaking.

mechtech2, I will see my mechanic at a party he is having tommorow, so I will ask him.

Thanks for all of the responses and suggestions, it is much appreciated.

 

[cousincletus]

Originally Posted By: Steve S
Originally Posted By: 40Deluxe
Agree w/your dad's friend.The old seal has probably cut a groove where it ran,the new seal will not seal in that groove.The part you need is called a readi- sleeve and installs easily on the yoke and gives the seal a new surface to run on.I have installed many of these and they work very well.I will always put one on the crankshaft seal surface if it is even remotely worn.
+1 on the redi sleeve ,well worth the cost, and check the runout on the pinion shaft to see it there is a worn bearing.


Agree. Worn bearings will cause seals to leak.

 

[Kestas]

If bearings wear to the point that they develop play, then something is seriously defective with the bearings. If they have simply taken a better seat, then clearance should be readjusted.

 

[onion]

And they could be loose because the bearing preload wasn't properly set. We already know that it wasn't done 'properly'. The question is whether or not he got it 'close enough'.