I have a 2004 X Type 3.0 automatic.
There is a whining noise that I can not figure out nor cam my mechanic.

It makes the noise when moving and it changes pitch with the speed.
The noise is there if I shut the engine off going down hill.

It is hard to tell where it is coming from but I think it is coming from somewhere towards the back, I can not tell what side.

When it 1st started I thought it sounded like a wheel bearing that was going bad, but it does not go away when turning one way or the other.

I changed brake pads all around and could not find any play in the wheels.

I took it to my mechanic who checked the wheel bearings again, the transfer case and rear differential and could not find anything wrong.

When on a rack running and in gear there is no noticeable noise when standing under it.

It had 2 tires that were wore a bit on the inside so I put 2 new ones on it and nothing changed. The other 2 were good so I had them balanced and checked.

My mechanic told me he was stumped and admitted he was not familiar with Jaguars or AWD cars in general. He mainly works on motor homes.

Before I pay a Jaguar specialist I wanted to get some advice from people that have the same type car and see if anyone else has had this issue.

I should note that the ABS light and Brake warning light are both on.
The only code that came up when checking the computer was a O2 sensor.

Anyone have an ideas? The noise is not bad just annoying. I can live with it if it is nothing bad because the radio drowns it out even at low volume.

The noise is more of a whine than a grind, it remindes me of a 4WD truck with large knobby tires

 

The probable cause is the driveshaft carrier bearing is dried out. Use a needle attachment on the end of a grease gun and insert it beneath the rubber seal and apply grease at 90 degree intervals and see if it doesn't quiet down.

 

I would think if it was the carrier bearing that would be pretty apparent if you were standing under the car. Could it be wind noise? Is it a high pitched sound? Does it change at all with speed? Does it happen at just certain speed ranges?

 

I do not think it is wind noise, it seems to be coming from under the car.
It sounds like a wheel bearing that has not gotten bad yet but it does not change when turning and the bearings were checked.
It seems to get a bit worse when there are more people in the car. Like the more weight the worse it is.

I am thinking about attaching 4 or 5 small microphones under it and listen to different ones when driving to see if I can get an idea where it is coming from.

 

How many miles on this car? Has transfer case ever been serviced? I'd start with that, then move on to the driveshaft center support bearing, then the differential. As far as brake warning light being on, when's last time the brake fluid was flushed? As for ABS light, if there were a fault I would think there would be a code stored, and the CEL illuminated. I recommend you attend to the mechanical stuff first, then work the electronics. Cars are machinery; they need to be kept serviced with adequate fluids.

 

the car has 120,000 miles on it.
I have no idea about the transfer case being serviced.I bought it this past September.

I am pretty sure the brake light and ABS is because of the rear sensors.

The mechanic said that he could not hear any noise from the transfer case at all. In fact I thought it was the transfer case when I took it to him. I had already tracked down a used one with a 12 month warranty. He was going to remove it but told me he thought it would be a waste of money but would do it if I wanted him to. Again he is not familiar with these cars. My options now are to pay a Jag Specialist in this area or drive it till the noise gets bad enough to be very noticeable.
The mechanic is not a shade tree guy, he is a friend that works on my cars only because he is a friend. He normally works on motor homes and always has work.
He did all the work on my Vette that had over 350,000 miles on the original engine when I sold it. I bought the Jag because I had back surgery and my other cars were not easy to get in and out of.
a 98 corvette and 86 Fiero GT. I am a big guy at 6ft3in 300 pounds.
I sold the Vette but kept the Fiero.

 

Please let us know how it turns out.

 

Typically... a wheel bearing will change pitch or intensity if you "load" it. That is..... obviously in a place where you can do this safely... get it rolling about 40 mph and then swerve back and forth kinda hard or make a sweeping turn...

Our X-Type had the dreaded carrier bearing whine. Always between about 35 and 50mph and then it disappeared above 55. 18 gauge grease needle and some good grease cured it.

If the rear differential is the issue, it can transmit the vibration (noise) into the driveshaft. Look at the how-to for changing rear differential fluid. It's a bit fiddly but not terrible.

These are inexpensive ways to start narrowing things down by going after what seems to be common issues. So before you start going down the Doom and Gloom road.... I'd check these out. It's stuff you probably should do anyways with your mileage and unknown service history.

 

I suspect these are the rear tires. If they are canted in at the top, you need new control arms. This situation puts extra torque on the rear bearings that causes noise and would not be evident on a lift with no load on the tires. If you replace these be aware of the locktite on the bolts. Heating them will make removal much easier. Here is a link at a very good price for the arms.

Jaguar X-Type Rear Lower Control Arm Pair. C2S50863 | eBay

 

Actually the 2 right side tires were worn the worst, the right front was almost to the metal bands on the inside and the right rear was also worn in the inside but not as bad.
I had the 2 new tires put on front and the old ones are on the rear.
I am getting 2 for the rear next week. They only had 2 in stock when I got them so I ordered 2 more identical ones. I am also having it aligned when I get the tires.
It is possible that the prior owner had rotated the tires before I got it.
Your theroy sounds plausible since the sound is not evident on a life and the more weight the more the sound is evident.

 

With that kind of abnormal tire wear I'd say you've got some worn-out front suspension pieces, like ball joints or tie rods. A decent alignment shop will let you know what they see.

 

I would lean towards the driveshaft carrier bearing, particularly because of your mention of it getting worse with passengers in the car. Mine started doing the same thing, but ONLY when I had passengers in the car. With a couple big fellows in there, it would do it all the time. Yet it would temporarily go away if I stepped on the brake. When the guys would get out, it would totally go away. I did the needle on the grease gun thing and problem solved.