I have a 97' Ram 1500, 4x4 with a 5.2L engine. My problem is that when I'm driving I hear this grinding noise( like you are going over rumble strips on the highway!). It only happens in 2wd and starts about 30mph and it will go away when you slow down or put it in 4wd. I was leaning toward a leaky vacuum motor on the front axle causing the the fork to "walk/creap" over and the splined coupler grinding on the inner axle.
It didn't appear that the vacuum motor was leaking and my vacuum lines appeared to be OK. I replaced the vacuum switch on the top of the t-case and I still have the problem!
I took the truck to the dodge dealer today to get it fixed and they said it was bad u-joints and a rear drive shaft that was out of balance. (It didn't make sense to me because why would it go away when 4wd was engaged, and to me it sounded like it was coming from the front axle)
Anyway $280 later and the problem is still there! (You would think the dealership would be the expert)

PLEASE DOES ANY ONE HAVE THE ANSWER?

 

I forgot to mention through other posts I also checked the clip on the rear output shaft going into the t-case and it was still there and working fine.......Please, please help me!

 

sounds like your having the same problem I am having... I think I have decided to wait until it is completely broken to fix it that way we know exactly what the problem is. What a horrible noise!!!!!

 

I get a similar noise in mine when I get over 55 anf let it decelerate on its own, it only does it from 60 mph down to 50 mph, in ger or not, clutch in or not. I'm guessing some 110,000 miles on u-joints is causing it. Or the rear pinion bearing. I will have to do some more highway testing. This only occurs in that range, out here in colorado I easily drive at 0ver 75mph on a weekly basis and sometimes I push it even higher so It is kinda strage with all this.

I will let you know what mine turns out to be if I figure it out. This all comes after performing a clutch job and 100% fluid replacement all around.

 

I was at the dealership this morning and went on a test drive with the service manager. He seems to think it is the Right from wheen bearing. I'm not so sure because the noise goes away as soon as 4wd is engaged. Also the noise (sounds like you are going over rumble strips on the highway) wasn't a gradual noise that got louder over time like a bearing going out. The occurrances got more frequent until it does it all the time. I still think it has to do with the front axle at the shift collar. The puzzleing thing is that my vacuum lines and vacuum motor test good. Very confusing....but I still think it is the vacuum shift motor not holding pressure in 2wd causing the shift collar to creap over and "grinding" on the inner axle.
PLEASE PLEASE I am desperatley seeking the answer to this problem!!
It is obvious the the dodge dealer, the so called "expert", is not sure what is causing it!

 

I was at the dealership this morning and went on a test drive with the service manager. He seems to think it is the Right front wheel bearing. I'm not so sure because the noise goes away as soon as 4wd is engaged. Also the noise (sounds like you are going over rumble strips on the highway) wasn't a gradual noise that got louder over time like a bearing going out. The occurrances got more frequent until it does it all the time. I still think it has to do with the front axle at the shift collar. The puzzleing thing is that my vacuum lines and vacuum motor test good. Very confusing....but I still think it is the vacuum shift motor not holding pressure in 2wd causing the shift collar to creap over and "grinding" on the inner axle.
PLEASE PLEASE I am desperatley seeking the answer to this problem!!
It is obvious the the dodge dealer, the so called "expert", is not sure what is causing it!

 

Well I just heard back from the dealership....They are now saying it is the Main bearings in the transfer case.
Does anyone know how much this should cost, and if this sounds like the answer to the problem I have been having?

 

It was the front Right wheel/hub bearing. The truck is fixed!