2000 Dodge Ram

Drive Train Axles Bearings problem
2000 Dodge Ram V8 Four Wheel Drive Automatic 157952 miles

4wheel drive does not go into gear, when in 2 wheel drive there will be a harmonic like sound going from not so loud to louder then stopping then doing it again. This will go on for miles then quit. This is allot more prone in the cold. If I have the shifter in 4 wheel drive this noise does not happen. There is a new actuateron this truck also new hub bearings and u-joints. The noise I here is not grinding noise and sounds like it is on the drivers side. According to the dash the 4 wheel drive is engaged but is not.
Carol stewart
January 9, 2010.

Check the 4wd vacuum actuator on the front axle.