Rear differential leaking gear oil?

Tiny
JESUS7B
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 180,000 MILES
Oil coming out of differential. I was told need to repair rear differential at a cost of $1,200.00.

Is this appropriate and worth it?
Monday, September 16th, 2019 AT 2:42 PM

15 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good evening.

If it is leaking from the axle seal this video will show you how to change it out.

https://youtu.be/ytqXLSjHNm0

Roy
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Monday, September 16th, 2019 AT 3:24 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
I attached the steps for removing and replacing the differential housing below for you.

https://www.youtube.com/watch?v=kLBxcXzyKYg

I also posted the steps below for the replacement.

Most repairs do not need to replace the housing as the interior of the differential can be rebuilt for less money than replacing the housing itself.

https://www.2carpros.com/articles/how-a-differential-works

Roy

Rear Axle Housing Replacement

Removal Procedure
1. Raise the vehicle. Refer to Vehicle Lifting.
2. Drain the axle lubricant.
3. Remove the rear axle assembly.
4. Remove the brake caliper brackets.
5. For the 8.6 inch and 9.5 inch axles, remove the brake rotors.
6. For the 10.5 inch and 11.5 inch axles, remove the hub and rotor assembly.
7. Remove the rear axle cover housing and gasket.
8. Remove the axle shafts.
9. Remove the brake backing plates.
10. For the 8.6 inch and 9.5 inch axles, remove the rear axle shaft oil seal and the bearing.
11. Remove the differential assembly.
12. Remove the drive pinion shaft yoke and the oil seal.
13. Remove the drive pinion and the inner pinion bearing.
14. Remove the pinion bearing cups.

Installation Procedure
1. Install the pinion bearing cups.
2. Install the outer pinion bearing into the axle housing.
3. Install the drive pinion oil seal.
4. Determine the selective shim thickness for the drive pinion.
5. Install the selective shim onto the drive pinion.
6. Install the inner pinion bearing onto the drive pinion.
7. Install the drive pinion.
8. Install the pinion yoke.
9. Install the differential assembly.
10. Adjust the differential side bearing preload.
11. Adjust the drive pinion to ring gear backlash.
12. Perform a gear tooth contact pattern check.
13. Install the brake backing plates.
14. For the 10.5 inch and 11.5 inch axles, install the hub/rotor assembly.
15. For the 8.6 inch and 9.5 inch axles, install the rear axle shaft bearing and the oil seal.
16. Install the axle shafts.
17. Install the rear axle housing cover and gasket.
18. For the 8.6 inch and 9.5 inch axles, install the brake rotors.
19. Install the brake caliper brackets.
20. Install the rear axle assembly.
21. Fill the axle with lubricant. Use the proper fluid.
22. Lower the vehicle.
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Monday, October 12th, 2020 AT 6:16 AM
Tiny
BARTZKENNY
  • MEMBER
  • 1 POST
  • 2002 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 80,000 MILES
Front differential is leaking on the drivers side shaft. Going to replace the seal but need to know what the torque specs are for the spline and center bolt.
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Wednesday, October 14th, 2020 AT 2:42 PM (Merged)
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
By spline and center bolt, what are you referring to? The only thing that needs to be removed are the 6 stub shaft to CV axle shaft bolts, and then the stub shaft SHOULD come out with some persuasion.
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+2
Wednesday, October 14th, 2020 AT 2:42 PM (Merged)
Tiny
SNAKE75
  • MEMBER
  • 5 POSTS
  • 2001 CHEVROLET SILVERADO
  • 5.1L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 344,000 MILES
The gasket from the transmission to the differential is wearing in one spot causing a ATF leak. I replaced the transmission and the gasket twice? What is causing that? Also the transmission and differential adapter is cracked like the old one also leaking ATF. I have not been doing any mudding or rough driving other then long distance for work. Found out I have a steel drive line and it is suppose to be aluminum. Could that cause the crack in the adapter and the gasket being worn?
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Wednesday, October 14th, 2020 AT 2:42 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,883 POSTS
Hello,

I have a quick question, do you mean the transfer case not the differential? If so there are shaft seals meant to hold the fluid in the gasket is not meant to. I think there is even a relief that allows the fluid to leak out when these seal leak. Can you upload a picture of the location of the leak so I can send instruction on how to fix?

Cheers, Ken
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
SNAKE75
  • MEMBER
  • 5 POSTS
It is leaking where the gasket is/was and the adapter has a crack in it. And yes the transfer case is what I mean. I can take a picture at the moment. I have a 68 1/4 inch drive shaft on it. The adapter is cracked on the transfer case side and the bottom is loose.
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
SNAKE75
  • MEMBER
  • 5 POSTS
I cannot take a picture at the moment. Sorry
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
DANNY L
  • MECHANIC
  • 5,648 POSTS
Hello, I am Danny.
I know a lot about Silverado's. The transfer case and transmission are sealed with an o-ring. Hope this helps and thanks for using 2CarPros.
Danny-
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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If something is cracked that is not good. If you can get a picture for us we can get you the repair procedure. I just need to see what you are talking about, but if it is what I think it is here are the diagrams to help you get it fixed.

Check out the diagrams (below). Please let us know what you find.

Cheers, Ken
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
SNAKE75
  • MEMBER
  • 5 POSTS
I know how to replace the adapter. But I need to figure out what is causing it.
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
SNAKE75
  • MEMBER
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I will try to get a picture today if I can.
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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Yes, please get an image so we can get the correct information.
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+1
Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
DAWNLAMPHAR
  • MEMBER
  • 1 POST
  • 1992 CHEVROLET SILVERADO
  • 16,300 MILES
Differential leaking. What does the differential do? How to repair and cost.
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)
Tiny
CARADIODOC
  • MECHANIC
  • 33,741 POSTS
The fix and the cost depends on what's leaking. Cover gasket takes less than an hour to remove it, clean it up, apply new sealant from a tube or install a new fiber gasket, install the cover, and refill it with new lubricant. Expect around $100.00 to maybe $150.00.

Axle seals are much more involved and the cost will be for mostly labor. A seal only costs a few dollars but the cover mentioned above has to be removed, then the differential must be partially disassembled so the axle shaft can be slid out to allow removal of the seal. At that point sliding the other shaft out to replace the seal on the other side only takes a few extra minutes so most mechanics will replace both of them at the same time. The logic is if one is leaking, the other one is just as old and is likely to start leaking soon too. The last step of the job is to reinstall that cover and refill with new lubricant. I could see this job taking two or three hours on the rear axle, considerably more on the front axle if you have a four-wheel-drive truck. The second seal will take an extra ten to fifteen minutes.

A pinion seal could also be leaking. That requires removal of the drive shaft, a very large tight nut, and the "yoke" the drive shaft attaches to, to get to the seal. It takes less time than doing the axle seals and the rear cover doesn't have to come off, but they will need to add new lubricant. Tightening that nut when it's reinstalled is a very precise procedure requiring special tools to prevent a droning gear noise. This job should take around two to three hours.

The differential is a set of four gears inside the axle housing that connects the left and right axle shafts together. Their teeth are beveled at 45 degrees so they mesh and form a square similar to a picture frame. Because of those gears, when you raise the vehicle off the ground and turn one wheel forward, the other one will turn backward. Now, that entire assembly has a big gear around it and is free to rotate on a pair of really beefy bearings. To make room for that big gear, called the ring gear, is why you see the big "pumpkin" in the middle of the axle housing. That ring gear is turned by the "pinion" gear which is turned by the engine / transmission / drive shaft. When the tires are on the ground and have traction, turning that entire assembly makes both tires try to move the truck forward. When anything makes one tire want to turn faster than the other one, those four smaller gears allow that to happen. That is necessary when turning a corner, and it is what allows one tire to spin on ice or in a mud puddle while the other one won't turn. Most race cars use a different system that forces both wheels to turn all the time at the same speed. The drivers put up with that since the tires are always almost sliding across the track, but for you and me, that would be extremely irritating to drive on the road. There are additional special parts that can be built into the differential to make both wheels try to turn at the same speed. That will tend to overcome just one wheel spinning when you're stuck. GM calls that "posi-traction". Chrysler calls theirs "sure-grip". There's a few different ways of designing those systems but they all try to accomplish the same thing. Except in very rare cases you will never find those types of differentials on the front of front-wheel-drive trucks and never on front-wheel-drive cars. Trying to hold the two front wheels to the same speed would make it very hard to turn the steering wheel and hold it there.

Every car or truck will have at least one differential on the front or rear, whichever has the drive wheels. Four-wheel-drive trucks, and all-wheel-drive cars and minivans, (technically not the same thing), will have a differential on the front and on the back axles.
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Wednesday, October 14th, 2020 AT 2:43 PM (Merged)

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