I have a intermittent knocking noise that I cannot pinpoint. Happens at speed (highway 50 - 65) sounds like a rotating knock. Faster at 65 than at 50. When it first happened I could get it to stop by taking my foot of the accelerator. Now nothing I do makes it stop it will just go away whenever with no apparent reason. Changed transfer case encoder motor 5 days before it started. Cannot tell where it is coming from. Do not feel it in the steering wheel or brake pedal.
If you put it neutral, does the sounds stay with the motor reving?
March, 23, 2013 AT 2:47 PM
2004 Suburban 115K with the same problem. Kind of a hammering noise coming from the ds rear end. Comes and goes, slows down with decreased speed, stops when in neutral. Rear diff fluid was low but sound continued after topping it off. No leaks. Braking has no effect. Put up on jack stands in gear and after awhile the sound came and went as usual. Rear end is open diff. HELP!