Humming/Growl noise in driveline?

[nsbs]

I will be a little long winded here but here is the problem with my 2001 Town Country AWD 3.8

Approx. 2 weeks ago noticed a humming/growling noise what appears to be coming from the driveline, it only makes the noise from 60km/h-70km/h then pretty much subsides. Took vehicle to garage and they put on hoist and the only noise they believe they here is from the rear differential. I was able to get one from a auto wrecker(the only one available in North America) and installed myself. Before installing I flushed both parts of diff and replaced fluid. Took vehicle for a road test and am still hearing the same noise.

I completely removed the driveshafts from PTU Unit to Rear Diff) and then took vehicle for another ride and there is no noise coming from driveline.

So I am beginning to think I have a bad diff, however it doesn't give you the tell tale signs of making noise when under load. Noise will be there whether vehicle is under load or not.

I have rules out whell bearings as there is no change in noise when manouvering from left to right at any speeds.

I have checked the fluid in the PTU and it is clean and was at the right level.

I see there is no hangar bearing available for this vehicle, instead they want you to apend $1100.00 for a complete driveshaft, but I dont see the hangar bearing being the problem.

I have even shut the vehicle off at the speed at which the noise begins just to eliminate anything else and the noise still persists.

Anyone have any ideas as to what is actually causing this noise?
Also if I drive vehicle as a FWD only(rear driveshaft removed) am I going to cause any damage to the PTU?

Looking forward to what anyone has to say.

Thanks

[jamesslcx]

Nsbs, how bad is the noise volume wise? A lot of vehicles make a humming noise, I guess if not too bad I would live with it, but as obsessive as I am it would probably annoy me.

[nsbs]

Originally Posted by jamesslcx

Nsbs, how bad is the noise volume wise? A lot of vehicles make a humming noise, I guess if not too bad I would live with it, but as obsessive as I am it would probably annoy me.

The noise was very irritating. Meanwhile I have removed the driveshaft and just finished a road trip for a total of 1300km. No noiseand no no issues running vehicle in fwd only.