Hello all....I'm having a problem with a grinding type of a noise at highway speeds. It sounds like a bearing has gone out...it's not a high pitch squeal, more of a deep growl. It's only when I'm cruising...if I step on it to pass somebody, it goes away....I haven't noticed it at lower speeds, say 60MPH and lower.

It's on my 96 S-10, Ext Cab, 2.2L, Automatic trans, with a 3/4 drop. I've replaced the U-Joints, Center support bearing, and at the new year, the trans was rebuilt. This did nothing for this noise....So I want to think it might be something in the rearend. Any ideas? Any ideas for something I could test? I know nothing about rearends....

Thanks for the help!:)

I forgot to add that it's an open differential, and the fluid level is fine.

Rebuild the CV joint at the rear of the drive shaft. This is very common in the extended cab S trucks.

Freddie,

My truck doesn't have any CV Joints, as it's 2wd. I replaced all of the U-Joints last week, along with the center support bearing....both did nothing. Any other ideas??? :)

All of the extended cab 2 wheel drive S10 trucks that I have been under had a CV joint in the drive shaft at the rear end. The CV joint has 2 u joints and a ball joint in the center of it. The ball is what wears out and needs to be replaced. GM sells a rebuild kit for it.

Freddie, I know exactly what you're talking about as our Jeep has the same thing. On my truck, in this order from the trans to rear end goes: Trans, U Joint, Front Shaft, Center Support, U Joint, Drive Shaft, U Joint, Rearend....there isn't one of those double u-joint ball things in there. :(

I chased this problem before..Do you have rear discs ? If you do the e brake could be rubbing in the rotor where the e brake is. Mine was went you went around a turn the axle pulls out of the carrier a little and rubs on the inside of the hat of the rotor. Let me know.

Tony,

I replied to your PM, but I'll just go ahead and post here too...

My truck has drums in the rear, and I don't notice any grinding when going around turns....but I don't ever take turns at freeway speeds either. It's only ever making the sound when I'm going down the freeway.....

Are you sure it's not coming from the front like a wheel bearing? Lift it up and grab the front wheels and see if they are loose.

Gilbert,

yeah I'm positive...its definitely coming from the rear end. I'm thinking its a bearing in the rearend...I'm going to experiment a bit more this Friday and see what I can find out....

If it's a pinion bearing, the noise should change when you let off of the gas. If a rear axle bearing is bad enough to make that noticable of a noise, then I would suspect that one of the axle seals would be leaking. Have you removed the differential cover to inspect for abnormal wear and tear on the ring gear and pinion, and inspect for abnormal metal shavings? One other thing that comes to mind is the transmission. Does the noise sound like a droaning noise? I know that the 2.2's don't have alot of power, and I see that you have had the transmission rebuilt, and from what I understand, it was doing this before the trans was rebuilt. Had it been rebuilt before this? The reason i'm asking is, because most transmission shops convert the lock-up torque convertor system from a pulse width modulated system to a on/off lockup. The factory pulse width modulated system allows the torque convertor clutch to slip a little, and the reason they did this is so that the customer couldn't "feel" the torque convertor lock in. Well on the 2.2, it uses a 10" high stall torque convertor, which produces excessive heat anyway, and with the clutch slipping, it creates even more heat. I had a customer complain about a droaning/grinding noise after we had rebuilt his transmission, and it was because we had converted the lockup sytem to an on/off, and it was causing the engine to lug, and the customer was feeling it. The easiest way for you to determine it this has been done is to drive the vehicle and get it up to temperature and at cruising speed, and let off of the gas, this should unlock the torque convertor, now slowly re-accelerate. If the engine rpm's instantly drop about 300,then it has been converted, if it slowly drops, then it is still factory. Another way is with a scanner, and watch the TCC slip pid, when the torque convertor locks up, with the converted system, it will actually show negative slip, where on the factory setup, it will show as much as 50 rpms of slip. This may not be your problem at all, but I thought that I would run this by you.

Jim,

The noise goes away if I let off the gas and the truck is coasting....or if I hammer the throttle to pass somebody or going up a hill it will go away. The noise mainly comes on mostly flat freeway cruising speeds.

The transmission had been rebuilt before the last rebuild....about 3 years ago. This noise started well after it was rebuilt the first time. I don't think they replaced the torque converter this first time, but they did this last time. I think it's the aftermarket model you're referring to because I notice when it locks up...not a clanking or anything like that, but you can feel the truck lose a few hundred RPMS. Unfortunately, my truck doesn't have a tachometer either. I'm headed to school right now, so I'll pay extra close attention to how the torque converter locks up on the freeway and I'll let you know tonight. Thanks a million for the help-
:)