Odd Noise At 1000rpm

[jhoff8487]

I've got an odd noise that is only audible at 1000 RPM. It doesn't matter as much if it's in forward or reverse. I took it in to the dealer for an oil pan sensor fault code and told them about it. They couldn't regenerate it, nor could I. I came home and played around with it a bit more and it's at 1000RPM exactly. It doesn't do it at 900 RPM or 1100 RPM. It sounds like maybe something is just rubbing to me. It is behind the cab so something in the rear end or drive shaft, I think. It was doing this before I cranked my torsion bars Wednesday so that is unrelated. Any ideas? Thanks.

[2000DV4.8]

Maybe a vibrating heat shield? Does it do it at any speed at 1000rpm, or just first/reverse?

[jhoff8487]

I notice it most in reverse but it does it at all speeds, as long as it's at 1000 RPM. Sometimes I can't get it to do it but usually I can. A vibrating heat shield is a good idea. I'll crawl under and check that. Thanks for the response, Dan. Any other ideas?