94 GC 4x2 rear-end

Hey, I am new to the Jeep forums... I work for a used car lot, and we have this 94 Jeep Grand Cherokee Laredo 4x2. It has an extremely loud whine in the rear end... I haven't heard the whine, but the owner of the lot was asking me a/b it... He's given it to a friend of his that does work for him, but he wanted to know what might be causing it...

I don't know too much a/b the problem, or Jeeps period, so I figured I'd ask the helpful folks here at AF... please tell me some possible things it might be, b/c I suggested wheel bearings, and the other guy shot that idea down...

Whining is usually the ring & pinion, if they are worn there will also be some slack in the gears. You can (with the tires blocked and trans in neutral) manually turn the drive line back some, sometimes (like one I had years ago) almost a half turn. Low fluid can cause excessive wear like this, so can extreme abuse (such as in my case). This is one of those hmmm.. I wonder if the previous owner was a numskull and didn't maintain the vehicle or a leak developed that wasn't noticed or the owner run the stuffing out of the vehicle and this was the first thing to break.
If it is a wheel bearing problem, you will hear crunching and grinding and in some cases, the wheel bearing is what holds the axle in place so the axle will come out and the tire will fall off when it breaks.
Some of the GC's came with the Dana 35c axle. In such case, the axle is too light duty for this vehicle and if you do any heavy towing, the axle will wear quickly. I think the max towing for the 35c axle is 2000lbs.

Whining is usually the ring & pinion, if they are worn there will also be some slack in the gears. You can (with the tires blocked and trans in neutral) manually turn the drive line back some, sometimes (like one I had years ago) almost a half turn. Low fluid can cause excessive wear like this, so can extreme abuse (such as in my case). This is one of those hmmm.. I wonder if the previous owner was a numskull and didn't maintain the vehicle or a leak developed that wasn't noticed or the owner run the stuffing out of the vehicle and this was the first thing to break.
If it is a wheel bearing problem, you will hear crunching and grinding and in some cases, the wheel bearing is what holds the axle in place so the axle will come out and the tire will fall off when it breaks.
Some of the GC's came with the Dana 35c axle. In such case, the axle is too light duty for this vehicle and if you do any heavy towing, the axle will wear quickly. I think the max towing for the 35c axle is 2000lbs.

ok, are these GC's FWD or RWD... b/c I was thinking rear axle, but I thought maybe they were FWD... thx for the help

They are rear wheel drivers. Front drive units won't handle towing heavy loads.

The whine could be the rear wheel bearings or Differential Bearings or Pinion Bearing. Most likely pinion bearings.

Find out when the whinning occurs, while applying the gas or costing or all the time.

If you hear noise with the bearings under load (while applying the gas pedal) then the rear pinion bearing is the problem, if it happen at a coast the the front Pinion Bearing is the cause.

It is possible, but not likely, the ring and pinion when they start to whine it is ussually because of lack of fluid. - Check the fluid if it is at the proper level then I would look at the bearings as the cause.

ok, the RWD thing makes sense... didn't really think a/b it though

ok, I haven't heard the whine, but it's coming from the rear, and is all the time (I'm told...) but I'll talk to the dealer and tell him what you've told me and see what he thinks