[Cody J]

I have a 1986 trooper 4x4 gas engine, manual transmission. I took it on a 400 mile trip this weekend, and on the way home it started making some ugly noise that sounds like its coming from the rear of the vehicle. It has always had some whining noise, but has never been this loud. I don't get the sound until I shift into 4th gear and get to 45+mph. The faster I go the louder it gets. Also when I let off or barely press the gas at these speed it intensifies the sound for a brief moment. I drained the rear end oil and replaced it, it was very black and it did not seem to help the noise. I am still getting it above 45mph. I was recently laid off work so I am trying to do all the work myself through books and forums. Any help would certainly be appreciated. Thanks.

Also, should there be any play in the center support for the driveline?

 

[oldestisuzuist]

Pull the rear yoke loose from the front of the differential, see if the pinion nut has loosened up. If so try torquing it to about 100ft-lbs, then stake the nut to the threads to lock it in place.
If this doesn't stop it then you probably have a bearing going bad and it won't get better, only worse. Replace the back third member with a salvage yard find, '84 through early '87 Troopers will have the correct 10-bolt diffy with 4.56 gears.

 

[lowzone]

had a 10 bolt that got low on fluid (pinion seal leak) and it would HOWL over 40mph. filled the rear up with fluid, it went away but it ended up being a outer axle bearing SPUN the race. it ran low on oil and spun the race, when it was filled again, it stopped the howling. sold the truck (actually a 2wd 1st gen rodeo) to an exporter 2 years later. check the fluid first.