2000 Dakota 4.7L, manual transmission, 33" tires.

The othe day I loaded about 2000 lbs into my box and drove about 15km on the highway, not driving hard.
Now my transmission sounds different. Hard to explain but it's kind of a metallic hum, similar to a dry bearing. It is audible in all gears but definitely loudest in 5th. Could the weight have done damage or am I just being paranoid?? Fluid level is fine but I'm going to change the fluid and see if that helps.

 

I was going to say if the fluid level was low combined with the change of fluid level with the weight in the back could have caused the input shaft bearing to run a little dry. Have you check the rear diff fluid? Does this sound increase with rpm?

 

Yeah, increases with rpm and goes away when cruising in neutral.

 

2000 pounds is heavy for the box but not for the truck to move. It can pull more than 6000 pounds so it isn't likely you overstressed the transmission.

How loud is the noise in 4th?

5th is an overdrive ratio so power goes through the countershaft. In 4th, it's direct.

Do you have a 2 piece driveshaft? The angle change may have put more of a load on the center bearing due to the weight.

 

Its a solid driveshaft

 

Further diagnosis. Sounds way worse in 4x4. I presume there are things spinning in the transfer case even in 2wd?? If so, and the problem is in the transfer case could explain why it's louder in 4x?
Any links/tips for changing transfer case fluid? I am new to this truck. Found a 10mm hex nut on the rear drivers side of the transfer case. Low oil! Also found a 24mm nut on the front passenger side of transfer case, fill nut is stripped and haven't been able to get it off. Am I correct in assuming both sides of the transfer case need filling??

 

Yes, things spin in both 2 and 4 wheel drive. Any time you move things spin.

The fill and drain plugs are both on the rear of the transfer case.

Do yourself a favor, download the FSM from this link.

https://dodgeforum.com/forum/2nd-gen...-download.html