Need Help - QX4 Grinding noise

[spb1313]

Need some help and hopefully someone out there has had a similar experience. Have a 99.5 QX4 with 115k miles. Overall good condition other than some rust issues. Have owned this truck since 2003 and had all regular maintenance done. Mechanically the truck has been fine but have had an odd problem lately. About 6 months ago was driving on the highway when I heard a sudden grinding noise from the right front wheel. It only lasted about 1-2 seconds then stopped, then about 10 seconds later it happened again. It was very similar to running over a rumble strip, just a quick noise and vibration. It only happened twice that first day. I took it to my mechanic who I trust and he inspected the front end and found nothing. I chalked it up to maybe I lost my mind and did hit some rumble strips or maybe it was just a one time thing. I didn't happen again for about 6 months, then all of a sudden Monday morning on the way to work it suddenly did the same thing. This time I was sure I did not hit rumble strips or anything else. It happened twice on the way to work, and it happened about 10 times on the way home. Every time was at highway speed driving straight, no turns, and I didn't hit any bumps. It has only happened on the highway (50mph+), and every time it only lasts for 1-2 seconds then stops. I had the truck in 2WD every time it has happened. I took it to my mechanic again, he looked again and found nothing wrong, he even took it up on the highway but nothing happened. I drove it home today with no issues.

No idea what it could be since it seems to be totally sporadic and other than this issue the truck drives great. Any ideas?

[fueler]

hmmm.... check brake pads?

brake pads have wear indicators that can make noise but it would be more of a metal on metal versus a rumble strip

[spb1313]

I don't think it's brake pads, pads are on OK shape and not hearing anything while braking, it only happens while driving at highway speed, no braking, turning, or bumps.

[ARKQX33V6]

Things that could go bump in the night!
1 Check all mounted tires for belt break down, remove and check inside out, pressures and profiles when loaded and mounted

2 Lock up torque converter failing at final drive speed

3 Rear anti lock going into spin, verify fluids, the do static test on drive wheel and compare turning of opposite wheel.

4 Check your ABS and see if it comes on when it should not, that involves brakes, pressures, release, e brakes, and the computer and all wiring

5 transmission ratios out of whack, but a MIL light should come on, but if none exists...this could also be a bump.

6 Wheel bearings, worn races, bad spots, test them

7 CV joints failing

Look for anything rotational that could offer a noise while turning with a changeable frequency determined by weight, application of pressure. Sorry to say that could involve a lot of systems. Finding an intermittent problem is time consuming but elimination of possibilities is needed and must be done with extreme care and since you are using a mechanic this process is expensive.

[spb1313]

Thanks for the checklist, will start working on these items to see what it could be. Some of these I can check on my own, others will suggest to my mechanic. Will let you know when we finally get to the diagnosis. Let me know if you have any other possible suggestions!