This is a long shot but need ideas what to look for. 2500, 4x4, 6spd manual, quad cab, 92k miles. Pulling 12k bumper trailer for about 2 hours. I came to a stop. Turned left and took off. Very minor tire slip in the sand/gravel.

Heard a noise start. Sounded like a very loud electric trailer brake noise. Or maybe bearing going dry ready to lock up. Got louder as I sped up. Maybe 20 mph. Came to a complete stop, no noise. Started again and had noise. Did not change with pressure on or off brakes. No performance issue on truck. Nothing hot. No leaks. Unplugged trailer still noise. A friend stopped and walked by my truck and could hear it. But could only say it wasn't coming from the trailer. She got me took off and it quit. I Took off again and heard it. Then I decided to try to get home and it just went away. Continued 6 miles home max speed 30 mph. Stopped in driveway. Slipped in gravel a little I I thought I heard it again. Unloaded truck and test drove. No sound.

A buddy thought maybe it was my antilock brakes. Maybe bypassing or something because it slipped. I was afraid it was bearing or read end. But everything looks perfect.
The best I can say was it sounded like electric brakes on a trailer when the magnet kicks end. But it was very loud and it only did it while I moved. And started with just barely moving

Any thoughts?

 

If it's a high pitched whine while you are moving, and increases in pitch as your speed increases, the first place I would look is the center support bearing on the rear driveshaft.

You can diagnose it by safely raising all your wheels off the ground on jack stands, then listen to the bearing with a stethoscope while a helper accelerates in gear to the speed where the noise was apparent. Also you can remove the rear shaft and spin the bearing manually and feel for roughness.

 

Change your differential oil. It could be your limited slip clutches chattering.

 

What do people like to use oil wise?

 

Personally I like synthetic 75w-140.

 

Rear end noises are tough to diagnose if you don't "know" what to look for. The pinion support bearing is common with the AAM axle. Check the front of the rear end at the pinion. When the bearing goes south it tends to take out the seal and you will notice gear oil on the bottom of the axle from the pinion back.
Start there and check the amount of gear oil or just change it altogether. The limited slip clutches would make noise, but only as they slipped, not after as you drove, and at 92k miles, they should be fine even if you abused the truck.

 

I have drove the truck a lot since then. Never a single noise. There is not a drip of oil anywhere under this truck. It's perfect.


I can't help but wonder if it wasn't the electric brakes on the trailer. But the person who walked beside me didn't think the noise was from there. The trailer is a 2014, with only about 1200 miles on it.


I'll be checking what you guys suggested soon.


thanks for the input.

 

The stock AAM limited slip differential in the rear axle of 2003+ Dodge 2500/3500 trucks are a gear driven Torsen type.

There are no clutches in this unit. This is why no anti-friction additives are necessary in these axles.