the incredible disappearing rumbling
So I recently inherited a 2001 Mazda B4000 truck and I am currently trying to rehab it. So far I have replaced the front pads and rotors, replaced an ABS sensor, and the EGR DP sensor. But the one thing I can't seem to fix is a rumbling noise that is present anytime the truck is moving(I can feel it through the floor). I have already checked the front and rear bearings, they all seem good. So I put the truck up on jack stands, all 4 tires off the ground, had the wife put it in 4WD and step on the gas. But much to my surprise NO noise!!! So what I got is a rumbling noise I can feel through the floor anytime the truck is moving but not when its up on jack stands. Any ideas?
I don't know anything about the history of this truck, but I did notice that the passenger side wheel hub had been replaced.
2001 Mazda B4000 4.0L 4x4 5-speed manual