Clunk Clunk Clunk (Pinion Bearing?)

[Evan Snyder]

So my Sierra has developed a clunk. At first I thought it was the tranny slipping but then I realized it didn't do it all the time. Now its getting progressively worse. I'm decently mechanically inclined but what in the world is a Pinion bearing where is it at and how do I make that awful noise go away?

 

Thanks!

Evan

[silveradosid]

the pinion is the shaft that connects your driveshaft to the rear diff, it has bearings

[Nanotech Environmental]

The clunk could be a lot of things. Could you describe when exactly it is happening? ie on take off? decel? steady driving?

[sdeeter19555]

Pinion bearings would typically cause a high speed whine...

 

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[NEFisher11]

I had my pinion bearing go on my truck. It doesn't clunk but whine very loud on the highway.

[bndawgs]

Intermediate steering shaft perhaps?

[anumber1]

I have never found a failing pinion bearing that clunked. Generally they howl.

 

I have replaced a lot of rear U-joints in GMT800s that clunked, squeaked or created a vibration.

[Evan Snyder]

Thanks for the replies! The clunking comes on when shifting from 2 to 3 normally after deceleration. It sometimes does going from 3 to 4 but not very often that's why I thought it could be the transmission. It hesitates very rarely. It would do it worse when the throttle body was acting up but after replacing that it's stopped a tad. I'm at a loss at the moment.

[Evan Snyder]

I took it to a local reputable shop and the service manage took a look at it. he said the shaft and u joint looked fine and that the noise I was talking about was very common in 07-13 body style GMs.

 

I've read other posts that say this noise is more of a symptom than an actual issue and others have said just grease it to make it go away. I've got an extended power powertrain warranty from the dealer I bought it from and they won't touch it unless it's dead in the water so that's kinda where I'm at. Any suggestions? Just lube her up and let her roll??

I took it to a local reputable shop and the service manage took a look at it. he said the shaft and u joint looked fine and that the noise I was talking about was very common in 07-13 body style GMs.

 

I've read other posts that say this noise is more of a symptom than an actual issue and others have said just grease it to make it go away. I've got an extended power powertrain warranty from the dealer I bought it from and they won't touch it unless it's dead in the water so that's kinda where I'm at. Any suggestions? Just lube her up and let her roll??

[Evan Snyder]

The steering shaft was another thought but it felt more like it was behind me rather than in the front...so aggravating.

[arcasey]

Sounds like the slip yoke on the the drive shaft to me. A lot of people have problems with those "clunking" as the vehicle gets older. You can put some grease on it and see if that eliminates your clunking....

[brucelimerick]

Sounds like one of your universal joints. The key symptom is when you take your foot off the gas and you get clunking. This will get progressively worse over time. If you don't fix it it the shaking will start to deteriorate your spline and your pinion. Sounds like the service manger didn't want to get his hands dirty. As for the dealer and warranty it should be covered.

I would get a pry bar and put some pressure on the u-joints to check for movement. You probably can't grease them as mine were sealed. That can be a quick check, clunk could go away for a short period but it will return shortly.

[Evan Snyder]

I'd have to look at the fine print in my warranty to see if the u joints are covered. for some reason I think they limited it to drive shaft tyranny and internal engine components only.

 

I've heard the slip yokes were a problem and very common on the 07-13s...I will keep you posted.

 

thanks for the replies

[brucelimerick]

They aren't expensive. They can do a lot of damage if left too long. It is not costly to eliminate this possible source. $40 an a couple of hours at most. Do both. They are a high wear item and take a lot of abuse especially if you are bouncing around off road. The other items mentioned should last the life of a vehicle.

[Evan Snyder]

UPDATE

 

 

Took my truck back to the dealership I bought from for a separate issue and they finally admitted to it being the slip yoke offered to grease of 60 bucks or replace it for almost 200 I laughed.

 

The truck has been using oil ever since I bought it and I've finally had enough. 1.5-2 qts every 3000 miles no way that's normal...and yes it's an AFM model. I've replaced the throttle body and come to find out that quite a few others have had the same exact issue as mine. Now the aftermarket warranty is having me do an oil consumption test, with my luck everything will come back normal at 1000 miles