Trans? Diff? Wheel Bearings?

[coors]

Going into the dealer soon for tires and an alignment and I want them to look at something for me. Before I go in I wanted to consult the brain trust. I am experiencing a humming/groaning sound at 40MPH when cruising at 1500 RPM's. It's an '06 Supercharged with 52k miles. I cannot tell where the humming/groaning is coming from. If I had to pick a location I would say the sound is coming from underneath the front seats to somewhere under the rear seats. Sounds like a bearing is going bad. The drivetrain is tight and there is no clunking during shifts. Any ideas?

The sound is very apparent when cruising at 40mph with the engine speeds at 1500rpm. Someone, mentioned that the tires on these trucks tend to "cup" and will cause a lot of road noise when near the ends of their life. But I find it hard to believe it to be tires. I think I can differentiate between unbalanced "cup" tires and a mechanical failure. Honestly, it sounds like it is coming from the trans.

I hear it in every gear. At least, 1st - 4th. It really sounds like its coming from the trans. As soon as I back off the throttle the sound goes away. Step back on the throttle the sound returns. That's how I know its not the tires. Starting to get worried. I just bought this thing approx. 6 weeks ago.

 

[coors]

UPDATE:
I had 4 New Conti's Cross Contact installed yesterday and the noise has subsided, but not completely. The truck is ALOT smoother and quieter. The worn tires were major contributor to the noise I was hearing, but I knew I heard something else. I asked the dealer to investigate.

First, the dealer (name's will be withheld) called me to say they traced the noise to the trans, and that it was normal, I flipped out! I just bought the truck from a dealer no more than a month or so ago and that's not what I wanted to hear. I said, NO it's not normal! I asked him, OK where in the trans is the noise coming from and what is making the noise? Something has failed internally, what?

A couple hours later I get a call, now they say it's not the trans, but the differential. They had several techs lift the truck on the lift,put the truck in drive and got it up to 40 mph (the sweet spot), and investigate underneath the truck. The techs all agreed the noise was coming from the differential. I assume the front diff. I didn't ask, there was a lot of other stuff going on and I didn't have time to go back and forth with them.

I am just being very observant? Does your Rover make a slight groaning noise when traveling down the road a 40 mph (1,500 RPM's)? Does the earlier front differential problem affect my '06 model?

 

[coors]

**UPDATE

Just returned from the LR dealer. They had the Rover up on the lift with one tech inside the cab and myself and another tech underneath the truck. We got the truck up to cruising speed, then heard the noise. There is no doubt it is coming from the rear differential. It sounds like grinding metal on metal. The noise is coming from dead center of the rear differential case. Yikes! As soon as we shift the trans into neutral the sound goes away. I guess the load is being relieved, i.e. less stress on the differential gears.

$100k vehicle and the rear differential fails after 50k miles of pampered driving. Really?!

I'm going to try to tackle the replacement myself. Any help in the form of diagrams and/or Rover specific literature is greatly appreciated. In return, I will document the procedure and share with the forum the process I take to replace it.
Thanks,

E

 

[rockcity]

I just swapped the rear diff in my P38 a few weeks back. about 3 of the teeth in the ring were completey chewed up. Seems like a common problem in the Range. I'm sure it's pretty much the same process on your 06', take off the wheels and remove the axles, disconnect the rear driveshaft from the pumpkin and tie it off, drain the diff, swap, then reverse directions. Total time: 2 hours. I'd say seal up the diff with RTV black. Apply liberally around the bolt holes.