Weird noise?

I have searched through here to see if others have had this problem with their TB and have seen some that are similar. But, to make sure I will restate my problem:

My 2002 LT TB started to make this noise like it's winding up when I'm driving down the road, loudest between 10 and 40 mph. I don't notice the noise as much at highway speeds. At first, I thought it was the tires, but ruled that out. What could this be? I would like an idea before I take it into the shop.

Another problem: my 4-wheeled drive light went off a few months ago and it would not engage into 4-wheel drive when switching the knob. What is causing this?

Fan clutch could be locking up causing this noise, common issue on these TB's, the 4wd needs to be scanned for problems, lots of issues with the switch, encoder and reprogramming issues.

Yep, the roar noise is a bad fan clutch. A roar on a cold take-off is okay. If it roars all the time, the clutch is shot. Unfortunately they are expensive buggers on the TB's. Around $300 just for the fan assembly! One thing you want to do with your 4x4 is exercise it every other week. Just flip it to 4x4 as you pull out of your driveway and turn it off after a few hundred feet. It keeps the front axle disconnect and the transfer case motor free & lubed. If you dont use it, they will freeze up.

Joel

I have same thing you described, noise increases and decreases with speed of vehicle but not RPM of engine or tranny related. Appears related to wheels turning but is not caused by tires. I am not convinced of fan noise because it is a consistent increase & decrease in noise level with speed of vehicle. Not wind noise either. Any suggestions? Thanks for any help or info someone may have.

Could be a wheel bearing , someone has to drive this for a proper diagnosis.

Here's a possible low-tech fix. Most 2002's including mine rattled like mad at about 2500 rpm. It was only the hood prop bar. When it's locked into place it runs right across the front of the plastic fan housing. Bad design. At the right RPM they rattled insanely loud. A small piece of weatherstripping between the two cured it.

Good find revaboy. Another common rattle trap is caused by the rubber hood bump stops. If they are not ajusted out enough, the hood will rattle at the hinge ends.

Joel