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STG · May 19, 2011, 05:46 AM

I have a 2006 Jeep Grand Cherokee (Automatic, 2WD, V6). I'm hearing a buzzing sound in at the rear of the vehicle, coming from the drivers side. I diagnosed that location by driving down the road and leaning back between the driver and passenger seats. The buzzing sounds a bit like when you drive over the rumble strips on the freeway shoulder, only much quieter.

I've checked the following so far:

- Checked the differential fluid; filled to the right level, no metal shavings
- Checked the pinion seal and differential; no fluid leaks
- Checked the tire; found no evidence of a nail or the like

I'd like to get this resolved before I attempt my 240 mile commute back to San Antonio on Friday (I live there, but work in DFW). Thanks in advance for any words of wisdom!

TxGreaseMonkey · May 19, 2011, 06:32 AM

. Check the rear brake pads--the wear indicator may be signaling it's time to replace the pads. Rear pads are smaller and usually wear out first. This is my bet.

. Check the ABS tone ring and sensor.

. Check the tire for a bad belt or unusual wear.

If the problem persists, which is unlikely, I would suspect the LR axle bearing. It's somewhat involved to pull the axle and replace the bearing on Cherokees. A cut-off wheel and cold chisel is often used to remove the old pressed on axle bearing and collar, whereas a press is usually used for installation.

STG · May 19, 2011, 07:05 AM

Thanks, TXGreaseMonkey.

The tire appears to be good. I'm going to take it to a shop. If it's the wheel bearing, that's a few levels above my competence.

STG · May 22, 2011, 06:52 PM

Upon inspection, there was wear in the inside of the tires. My rear brakes were also shot. I had the rear tires replaced... and also found at that point that there was one other bad tire. As this vehicle has drained my wallet over the last few weeks, I just subbed my spare (it had never been used) for the one remaining bad tire. Now I have one used and two new Goodyear Assurance Fuelmax tires on the truck and one Goodyear Wrangler HP tire (the former spare). The wheel (or maybe the tire) that the Wrangler HP tire is on is still making noise.

Could this be a CV boot... or is the wheel bearing the most likely culprit? I took a video of it when I was driving today.

STG · May 22, 2011, 06:53 PM

Here's the video link... as it's not showing up in my post.

http://youtu.be/G2mAqQ9NpVM

TxGreaseMonkey · May 22, 2011, 07:26 PM

It's hard to tell for sure where the sound is coming from. I'm inclined to say tire tread whine. I would totally rule out the tires, however, before tackling the axle bearing. If you end up replacing the LR axle bearing, refill with the proper weight Mobil 1 Synthetic Gear Oil--bearings run cooler, quieter, last much longer, and you get better gas mileage. Ensure they don't overfill the differential.

STG · May 22, 2011, 07:31 PM

I'm going to check the bearing - as the tire that's noisy has all of 250 miles on it.

Any suggestions for going about that? It would be much appreciated!

TxGreaseMonkey · May 22, 2011, 07:39 PM

I recommend that you take it to Jeep for evaluation and repair. Find out if the differential is supposed to have a friction modifier added to the gear oil.

STG · Sep 13, 2011, 02:40 AM

Just as a follow-up...

The noise turned out to be bad pinion and side bearings in the rear differential. I took it to a shop in San Antonio for repair - they were unable to fix it despite having it for a total of 11 full days over multiple visits. A visit to a Chrysler/Jeep/Dodge dealer had it fixed in a matter of a few hours (and $1200).

Now I'm getting a similar noise from the front passenger side (the vehicle is a two wheel drive). I'm guessing it has to be the tire, as the noise is intermittent and isn't always audible.