5 different mechanics, $4,000 in parts, still no answer..

[Carey251]

Good Morning Everyone,

First time posting here. I have come out of desperation for a mechanical issue that no mechanic seems to be able to identify.

I drive a 2008 Tahoe LTZ 2WD, with about 100k miles. Over the last year, the vehicle has been making a whirring noise that has progressively gotten worse. The whirring noise only happens when driving up over 50-55 MPH, and when on the gas. The whirring noise goes away almost instantly when I let off and then comes back on again when I tap the accelerator. The noise seems to be the worse when I am driving on the free, up slight inclines, and when I let off the accelerator, and then tap the accelerator again.

To date, I have been to 5 different mechanics, all seem to think it is coming from the transmission or differential, but at this point, I have replaced nearly every part in both.

This far I have replaced:
-rear wheel bearings
-all new bearings in the rear differential, including the pinion bearing (a few mechanics were certain it was the pinion bearing).
-had the transmission rebuilt
-had a new pinion and ring installed (pinion was worn down a bit and wasn't in great shape)

After seeing the pinion, I was certain I finally had it fixed and it didn't make the noise while driving the next day after replacement. However, the second day after it was replaced, the noise was back and almost just as bad.

Everyone thinks it is drive train related but it sounds like it is coming more from the front portion of the car. It really sounds like a bad front wheel bearing, but it wouldn't make sense, as it only happens at high speed, when on the gas, and goes away almost as soon as I let off the accelerator.

Has anyone heard of a problem similar to this? My Tahoe is in immaculate shape, I would hate to trade it in, but at this rate, I am close to giving up.

Any input is greatly appreciated!

Thanks!

 

[randeez]

Was the torque converter replaced with transmission?

 

[Carey251]

Yes, the torque converter was replaced.

I don't know if it is worth mentioning, but the first day after the pinion and ring were replaced, I thought the problem was solved. There was almost zero noise coming from the vehicle and on this day it was about 70 degrees. This morning, there was a freeze and it was about 28 degrees. This morning, while driving in to work in the cold, the noise was just as loud as it has ever been. I don't know if this has something to do with it, or if it is just a strange occurrence.

 

[swathdiver]

Welcome aboard Quinn! Sorry to read about your frustrations with this truck. Let's zero in on when the noise went away. This happened when a ring and pinion were installed but if not done right they'll whirl away so as the old adage goes, even new things break or in this case, if it wasn't installed right, it's not fixed.

Where do you live? Maybe there's folks on here that could drop by and help and we'll certainly do our best from these keyboards.

 

[Carey251]

Swathdiver, the pinion and ring were replaced by a shop that specializes in differential work, but that doesn't mean they don't make mistakes- I really hope this isn't the case.

The sound from the driver seat really sounds as if it were coming from the front driver side area of the car, but as we all know, sometimes it is hard to determine the location of a problem based on where we think the noise is coming from while driving.

I am located in the DFW metroplex, Dallas to be exact.

 

[BobDobalina]

Id swear it would be pinion gear. HAving owned several POS Grand Cherokees, I am VERY familiar with it.

 

[swathdiver]

I reckon by your posts the truck isn't 4WD. Hub bearing noise can come and go as the loads shift. However, since you said it was gone for a day and then came back after that specific work was done that is where I'd zero in if I were you. I'd go so far as to drop the rear cover and see how the ring and pinion gears are meshing, there are photos of what's good and what's bad for our trucks.

 

[Carey251]

Thanks for your response. I am thinking about purchasing the front wheel bearings and having them installed, since this is relatively cheap to do, and with the mileage on the vehicle, it likely needs to be done anyway.

If the noise persists, I am going to find another differential shop to make sure the gears mesh properly.

 

[Scottydoggs]

dont these shops stand behind their work? id go back to the shop that did the rear and have them re check it.

no ones strapped a cam under the truck yet? best way to pin point odd crap. move it around till the sound is its loudest.

 

[jerryjoe28]

I would hate to guess what it could be, are there no shops in you area that can do a true noise test and find out where the noise is coming from? preferably a multi mic and camera test. they would attach multiple mics to the under side of your truck and drive it. then the machine would tell them what area the noise was coming from. after the know the area they can attach the mics to different places in that area and put a camera on it so they can see what is going on. this is by far the best way to go about it as u wont be wasting any money on parts you don't need!