Attention: TDR Forum Junkies I searched for something like this and couldn't find it on here. Maybe I have something no one has encountered? I hope not!
Here's my concern: I have an '01 2500 4x4 5spd with ~31k miles. Every morning that it's below, say, 60 degrees my truck develops a sound similar to a bad or failing wheel bearing. It's a rapid "thud-thud-thud-thud" sound. Weird thing is it only happens between 1700-1800 rpm no matter what gear I'm in, and it seems to have the same tempo in 2nd gear as it does in 5th, and only when under light load such as maintaining speed or accelerating slowly. When decelerating from above 1800 it's not there as it passes through to below 1700. It totally goes away after about 20 minutes of driving.
My first thought was that it was a natural reverberation caused by the cooler fuel circulating through the fuel system. I know the fuel heats up as you drive the vehicle and the warmer fuel may not cause this sound. Of course, I'm no mechanic, this is my first diesel of any sort, and I'm paranoid about lift pumps and failing VP44's. BTW, fuel pressure is 14 psi at idle and 9-11 psi under moderate to heavy acceleration so I suppose I can rule out a lift pump failure. Maybe it's about to let go? I dunno. I also considered that it may be coming from the transmission (it's coming from up front *somewhere*), however shifting feels the same before and after the sound comes and goes. I did just change my rear diff oil, but put 75-90 weight in it.
Should I be worried about one of the two fuel pumps or am I hearing a pilot bearing or something altogether different?
As always, any and all help is greatly appreciated.
Duane
Here's my concern: I have an '01 2500 4x4 5spd with ~31k miles. Every morning that it's below, say, 60 degrees my truck develops a sound similar to a bad or failing wheel bearing. It's a rapid "thud-thud-thud-thud" sound. Weird thing is it only happens between 1700-1800 rpm no matter what gear I'm in, and it seems to have the same tempo in 2nd gear as it does in 5th, and only when under light load such as maintaining speed or accelerating slowly. When decelerating from above 1800 it's not there as it passes through to below 1700. It totally goes away after about 20 minutes of driving.
My first thought was that it was a natural reverberation caused by the cooler fuel circulating through the fuel system. I know the fuel heats up as you drive the vehicle and the warmer fuel may not cause this sound. Of course, I'm no mechanic, this is my first diesel of any sort, and I'm paranoid about lift pumps and failing VP44's. BTW, fuel pressure is 14 psi at idle and 9-11 psi under moderate to heavy acceleration so I suppose I can rule out a lift pump failure. Maybe it's about to let go? I dunno. I also considered that it may be coming from the transmission (it's coming from up front *somewhere*), however shifting feels the same before and after the sound comes and goes. I did just change my rear diff oil, but put 75-90 weight in it.
Should I be worried about one of the two fuel pumps or am I hearing a pilot bearing or something altogether different?
As always, any and all help is greatly appreciated.
Duane
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