Noisy rear axle

[waxer]

My Legnum has started making a "hollow" droning noise from the rear axle, which gets worse on journeys over 10-15 miles. The wheel bearings seem fine, and changing all the AYC fluids has made no difference. At times it sounds as if the diff is about to explode. I've searched the forum, and can't find anything similar, and I don't know how else to diagnose it (except wait till it breaks). The AYC is still functioning properly and the car drives fine but it's very worrying. Can anyone advise please?

[bradc]

Are you sure it isn't the transfer case? Does it tend to get louder the faster you go?

[Nick Mann]

My question was going to be the same as Brads.

Are your tyres the same all round? When was the last time you dropped the fluid in the t/f case?

[waxer]

I haven't done that one since last April, cos I was fixated on the back axle; and yes, it does get louder at higher speed. All the tyres are the same.
I will change it ASAP and report back.

[wintertidenz]

I have the same symptom on my car - drone that gets worse as you accelerate. Apparently if the sound changes when you swerve from side to side it's the wheel bearing...
Will find out where my sound is coming from exactly so you can check if yours is the same :)

Also - is the sound on only one side?

[waxer]

I changed the oil in the transfer case today- the stuff that came out was almost like new, and it didn't affect the noise at all. Then I dropped the oil in the rear diff, and it was like bile. I put in some cheap gearbox oil, having put the last of my Amsoil into the transfer case, and a quick road test revealed the noise to be lessened, but still there. So it's obviously a problem with the diff, something that has wrecked the oil after a short amount of use. I think I'll drop the mineral oil I've put in, replace it with something better, then see what happens next.

[bradc]

Err what oil did you put into the transfer case and diff?

[waxer]

Amsoil SVG (Severe Gear Synthetic Extreme Pressure Lubricant 75W-90)

[bradc]

Ahh ok cool. It just wasn't apparent from the way you worded the above post whether you had put in gear oil (SVG) or gearbox oil (ATF or MTG)

I'd put some more into the diff again and see how it runs after that.