Joining the rear diff club

[jdoodle]

If you scroll up the thread you will see photos I posted.

Oh yeah, I remember them.

 

[remmy]

thread from the dead...

Happened to me too. Thank you all for the heads up. I changed my oil and while on the lift I inspected the rear diff. Sure enough, a gear oil sheen was all over the housing above the diff. Took it in to the dealer for warranty work for a new tail light and mentioned the pinion seal leaking. They put one on order.

 

[jdoodle]

thread from the dead...

Happened to me too. Thank you all for the heads up. I changed my oil and while on the lift I inspected the rear diff. Sure enough, a gear oil sheen was all over the housing above the diff. Took it in to the dealer for warranty work for a new tail light and mentioned the pinion seal leaking. They put one on order.

Remmy, if they are just going to replace the seal, keep an eye on it. They replaced mine and it took about a month for it to start leaking again. Then they replaced the entire rear diff.

 

[Crispy]

Our pinion seal was replaced last November at 18k. I just checked it and good at 4 months and 2k miles. Not a big mile-stone I admit but so far, so good.

 

[toolmanAR]

As the owner of multiple antique and classic cars, I am very confused by fretting over a damp pinion seal.

 

[Crispy]

As the owner of multiple antique and classic cars, I am very confused by fretting over a damp pinion seal.

These aren’t antique/classic cars. The more I learn about the GKN Twinster dual clutch diff, the more I don’t want mine to fail. Our underbody was coated with gear oil. I’m sure the other fails are similar. Doesn’t seem trivial to me and I’m happy people are helpful enough to share their stories so I know where I stand. Not trying to start a peeing match, just not sure about the comparison. C.

 

[ChibiBlackSheep]

As the owner of multiple antique and classic cars, I am very confused by fretting over a damp pinion seal.

Because parts aren't cheap and these newer cars are typically a DD for people. Add in a slow leak can lead to full failure later on in the car's life... right after the warranty for some.

I also have multiple fun cars, but if they go down for any reason... I can still get to work, get the kids to daycare, etc.

 

[Rhetoric]

Because parts aren't cheap and these newer cars are typically a DD for people. Add in a slow leak can lead to full failure later on in the car's life... right after the warranty for some.

I also have multiple fun cars, but if they go down for any reason... I can still get to work, get the kids to daycare, etc.

^^^^^^^^^^^ Yep.

 

[jdoodle]

As the owner of multiple antique and classic cars, I am very confused by fretting over a damp pinion seal.

If mine would have just stayed "damp" it wouldn't have been a problem. Unfortunately, damp turned into a dripping leak and I didn't feel like crawling under the car and topping up the rear diff. as part of my regular maintenance, as well as having in the back of my mind complete seal failure every time I drove the car.

 

[Jack GS]

That's a good point. GM has a service information document, Bulletin #15-00-89-004C, aimed specifically at differentiating between leakage and seepage (their terminology, not mine lol). They claim seepage, or dampness, is considered a normal condition.

When fluid droplets exist, it is considered leakage and not normal.

 

[remmy]

Remmy, if they are just going to replace the seal, keep an eye on it. They replaced mine and it took about a month for it to start leaking again. Then they replaced the entire rear diff.

Thank you sir, already planned on it as from what I gather, a complete replacement seems to be the answer in many situations. Our diffs must get all been built on a Friday...

 

[94cruiser]

I don’t think that it’s normal and that the bulletin is there to buy time.

Droplets within 15 minutes is a bad leak IMHO.

that would be a substantial amount in a 24 period.

also consider what is leaking - a power steering fluid from a small reservoir will loose more % of fluid than a transmission would.

 

[HotwheelHTH]

Here to say that the GS is susceptible to the same issue. I just returned home from a road trip(900 miles) and noticed my car left a puddle of fluid on the ground and smells hot. Also it's making a loud humming noise when moving. It will be going in next week for repairs, although it may hurt as it has 88,000 miles and is only covered by an extended warranty. Will post updates once they have diagnosed the problem.

 

[RegalMN]

Are you saying that the Chevy Dealer is ordering the part and doing the repair under warranty?

I once spoke with my local Chevy dealer who told me that they could NOT do warranty work on the Buick. They could service, but not warranty work.

Who is right?

I have had a Buick dealer do warranty and recall work on a Chevy.

 

[PrincipalDan]

Whether or not I will buy say a CPO Cadillac will be very much dependant if the Chevy or the Buick/GMC dealer will do warranty work.

Nearest Cadillac dealer is 130 miles away.

 

[Wlepse]

Just did an oil change and checked mine, not easy to see in this picture but there is some cast off on the housing. So I will have to plan a visit to the dealer to have them look at it.

 

[Jack GS]

Just did an oil change and checked mine, not easy to see in this picture but there is some cast off on the housing. So I will have to plan a visit to the dealer to have them look at it.

Just keep in mind, seeping fluid that only wets the casting is considered OK. Unless there's a consistent 'drip' they may not take any action.

 

[Crispy]

Just did an oil change and checked mine, not easy to see in this picture but there is some cast off on the housing. So I will have to plan a visit to the dealer to have them look at it.

Yeah, what JGS said. Ours was pretty noticeable above the diff. If you don’t have a way to get the car up, even drive up on a curb or across a low spot so you can get under the car and see the painted underbody above the diff. If it’s leaking enough to wet the slinger, you will see it above the diff. Good luck.

 

[ZB Commodore Owner]

In post 147 I mentioned the dealer had noticed my rear diff was leaking. They fixed a blocked breather. I got the distinct impression this was a known issue. As the diff heats up the air inside the diff expands and since the breather is blocked oil is forced past the seals.

Recently I took it back for them to check and the leak has stopped.

It might be worth mentioning to your dealer to check the breather.

 

[HotwheelHTH]

Here to say that the GS is susceptible to the same issue. I just returned home from a road trip(900 miles) and noticed my car left a puddle of fluid on the ground and smells hot. Also it's making a loud humming noise when moving. It will be going in next week for repairs, although it may hurt as it has 88,000 miles and is only covered by an extended warranty. Will post updates once they have diagnosed the problem.

UPDATE: left rear axle seal gave, lost about half of the fluid, remaining fluid is black and has metal pieces. Have to replace entire differential. Repair is ~$3,000, waiting for extended warranty to cover the cost.