Help with occasional grinding noise, cured by pressing gas (2 Viewers)

[Climr]

I’ve got a 97 and getting an occasional grinding noise coming from somewhere in the front part of the drivetrain. From previous searches I was thinking that it is dry spindle bushings, but the noise goes away when I give it some gas, which I wouldn’t expect??? with spindle bushings? Here are the details:

Where is it coming from: It’s really hard to pinpoint other than the front of the vehicle. I can feel the vibration through the gas pedal and the shifter when it happens.
What does it sound like: kind of like ‘grrrrrrr’ . Sort of like if you tried to shove a manual transmission into gear without using the clutch. It‘s easily audible (not subtle) even over the radio.
How often does it happen: On average about once every 5-10 miles of city driving.
When does it happen: It happens when I’m off the gas, between 10-40mph and going over small bumps on the road. It has never happened on the interstate and I don’t think it’s ever happened when I was on the gas.
What makes it stop: Pressing the gas or waiting a few seconds and it will stop. It’s never lasted more than about 5 seconds.
What doesn’t make it stop: Pressing the brakes has no effect, shifting to neutral has no effect.
Other clues: The birfields were rebuilt about 3K miles ago alone with front wheel bearings. I didn’t do it so I’m unsure about the status of grease in the birfields.

I don’t like the idea of digging into things without a pretty decent shot that I’m going after the correct problem. Has anyone had similiar issues and solved it? Any ideas?

Thanks!

 

[voodu3]

I would start with checking your front drive shaft. I have a similar noise. I removed the front drive shaft and it went away. I hope this helps.

 

[REKCUT]

x2 on front drive shaft. Ujoints will make noise while coasting and quiet down under load. Block the tires and put the transferase in natural and get under there and twist drive shaft back and forth while paying attention to u joints. You can go farther and remove front drive shaft and drive truck to see if noise goes away. You'll have to lock the center diff. If you don't have button then you can do it by putting in low and pulling fuse and shifting back to high

 

[Flightrisk99]

I had this problem. It would make a grinding sound when I lifted off the throttle downhill or over 70 mph. Greasing the u-joints would temporarily resolve it. Then I replaced the u-joints and that resolved it.