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2006 chevy trailblazer_ls
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Discussion Starter #1
Hey everybody. I'm generally a lurker on the forums since I usually find what I'm looking for has been answered/discussed 10 times over before I get to the party, but this time its not the case.

Here is the skinny:

-06 TB LS - i6 4x4 with GU6 3.42 Non-locking Rear End 189,000 miles

-Whining/whistling/groaning (not grinding) noise from rear end. Almost sounds like blowing air over a half empty beer bottle mixed with an electric motor. Pitch is higher at higher speeds.

-Rear end noise becoming more pronounced. Used to only be heard at "highway speeds" (50-75 mph) now can be heard at a lower pitch around 35-40 mph. Used to be able to drown the sound out with the radio but that isn't the case anymore.

-Only present when on the accelerator. Noise disappears when coasting and braking. Reoccurs as gas is reapplied.

-Same going straight or turning, coasting flat or down hill.

So digesting the info above I'm leaning towards a bad pinion bearing but I have ZERO slop from the shaft to the rear diff so I'm not 100%. Last fluid change did not resolve or even improve this. It is now time to change the fluids again though. The fact that it only happens when on the accelerator really eliminates a lot of issues. I'm hoping there is someone else out there that has seen this and can point me in the right direction. Thanks for your time!

*Moved from OEM issues after no hits*
 

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Sir did you ever figure out what this was? I believe I have the same noise going on and I cannot figure it out.
 

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Sounds like the gear contact pattern has shifted --- this isn't good.

It might be a bad carrier bearing - which I suspect first.
It might be a bad pinion bearing - which I suspect second.

Either way - drop the rear cover and look for metal paste or sparkles in the lube oil.

It may be too late to just replace the bearings - because you develop bad tooth contact wear patterns if the dimensions vary at all.

The ring and pinion do not like being in the wrong position even intermittently and they will destroy each other if you ignore the sound in the differential - which you appear to have done by turning up the volume of your music.

Unless you are totally familiar with rebuilding a differential - don't start. Leave it to an expert.


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