'98 Humming noise from rear end

[jb1966]

My 98 Rodeo has been making a humming sound from the rear end, over the past 2 years now that's getting gradually louder every month. I've had a rear differential sieze on me before (the day after I bought a used car a few years ago) and this sounds exactly like the sound that came from that rear end just before it siezed.

I've had my truck to the dealer many times, replacing all 4 tires, then all 4 wheel bearings, then draining and refilling the rear diff, all with no effect on the noise. They're telling me that the only thing left is to rebuild the rear differential and it will cost a small fortune. Well...I've already paid a small fortune to have this stiff done so far. Help! Here's is some info about the problem:

-mileage = 108,000Mi/180,000KM
-noise coming from center of rear end
-not linked to engine rpm
-gets louder and higher pitched at higher speed
-noise is loud when under "load" (pressing accelerator)
-noise stops when coasting (foot is removed from accelerator)
-noise doesn't change when turning left or right

[Ramblin Fever]

4x2 had a lose center carrier bearing, flaw from the plant, as truck only had 12K miles on it when that problem came up.

I don't remember a noise, however, but truck vibrated badly, wouldn't stay in alignment, and tires were excessively balanced. Dealership kept telling me nothing was wrong, I paid $65 bucks to have a driveline shop look at it, and write in detail what the problem was.

Dealer finally fixed it under warranty, after complaining for a year.

Obviously, you're out of warranty, but can you tell for sure if it's the rear axle or the driveshaft?

When did the noise start?

My truck now has 122K, and I've never had another driveshaft or axle issue since; and my first rear axle drain/fill came at 80K miles.

[jb1966]

Thanks for your message! I'll get my new mechanic to have a look. I've pretty much given up on the dealer - especially in light of the fact that they've dropped the Rodeo line in Canada much to my disappointment.
This has been a great vehicle all long and I've owned it since new.

To answer your question, it's a 4x4 and the noticable humming started two years ago at about the 60,000Mi/100,000KM mark. I say noticable because it has increased so gradually over such a long time but might have started before that. I was beginning to think that maybe the differential gears had worn a bit and therefore were spaced incorrectly and that this was causing a meshing "whine". But your suggestion sounds more likely because it sounds SO much like a bad bearing to me.

Is the center carrier bearing the one on the front end of the differential case where the driveshaft connects?

[johnsm]

check your recalls


http://www.alldata.com/TSB/29/98292337.html

I don't know if this applies to your problem.


SB00-06-S002 MAR 00 Recall - 00V058 Rear Axle Lower Trailing Link


I have a 2000 4wd and have a recall about loose hardware on the rear suspension.


John