2002 Overland Grinding Noise
I have searched and read for hours before i decided to post but i am hoping maybe a couple people will be up for discussion. So I bought a 2002 GC Overland 4.7 HO with quadra drive and tow package last week. I notice there is a grinding noise come from the rearend which at first sounded like rusty brakes after a car sat for a while but the noise didnt go away. The noise is constant after 5-10 mph. And the scrapping/ grinding pattern increase as the speed of the vehicle increases. Foot on gas or not
After a while i thought the axle bearings were bad but the sound is too metal on metal, not a low pitch hum like the axle bearing plus I called the previous owner who said all 4 axle/wheel bearings were replaced less than 1 year ago. Then I thought it was ebrake because it was making a grinding noise when i manually rotated the wheels. Pulled rotor, cleaned and adjusted, didnt help. Checked rear diff fluid and there are metallic flakes in the oil. Maybe from a bad axle bearing that had been replaced (I noticed dry bearing grease on the inside of the rim) or worn diff. I also get the commom grinding noise while turning when no FM is used. Can bad diff oil or lack of FM create this much grinding noise? Could it be u-joints? Hayes manual states for troubleshooting that a constant grinding coming from the drivetrain would be a u-joint. I have moved the driveshaft and see no play but the u-joints look rusty.
Tomorrow i plan to change the diff fluid and see if that helps. Not 100% sold on the u-joints just because i know nothing about them and what to look for. Also i noticed a little end play on the rear axles earlier. Not up/down or left/right but in/out. I am convinced almost to a fault that this noise is coming from the rearend. So i havent even looked at the transfer case or front end.
Any help or direction would be appreciated, i would hate to take it to someone not having an idea of what is going on.