Front end noise in 2wd but not in 4wd

Greetings -

I'm driving a '96 with auto trans, 3" lift, and over the past few months I've noticed a steady clicking noise when I'm rolling at 5-25 mph (I assume it's still there at greater speeds but I just can't hear it) . It's been getting louder the last couple of weeks. The noise is only there in 2wd, when I shift it to 4wd the noise goes away. (It also doesn't matter if I'm turning the wheels or going straight). When I put it back to 2wd the noise reappears. The noise also doesn't appear to be brake related. Any suggestions on what's causing the noise? Thanks in advance, Dan

Have you checked the transfer case shift linkage to make sure it's completely disengaging in 2wd mode?

Rob

Frt. axle joints loose?

Brian

Thanks for the suggestions guys, I'll check both the axles and that the 4wd is disengaging and post the results. A couple of more points:

1. The noise seems to only appear after I've been driving for a while on the highway i.e. when I drive around town I can't hear anything.
2. I can feel a slight "bump" in the brake pedal when I apply the brakes, but only when I hear the noise. If I'm driving around town, I hear nothing and feel nothing when I brake. When I've been driving on the highway and then get in traffic, that's when I hear the noise and feel a slight bump/pulse in the brake pedal.

Thanks and I appreciate your comments!

Dan

Your first post said nothing brake related. Loose axle joints, I mean really loose no needle brgs. left, will often make a steady clicking noise at city street speeds as the shaft flops around. In 4wd they are loaded and so the noise normally goes away or quiets. If in fact you have some brake related symptoms, then that probably isn' where the noise is coming from. Could also be coming from the double cardan joint on the frt. shaft. Or a rr. if that has been modified.

Hi - I appreciate your help and I'll check all you suggest - and please let me clarify "not brake related". I meant to say the noise doesn't appear to be related to the application of the brake pedal, but when I do apply the pedal, I can feel something that's simultaneous to hearing the noise. (In other words, I'm confident saying it's not a warped front rotor, semi-seized caliper, hanging rear brake shoe, all that kind of brake stuff). The key to the mystery I think is the fact that the noise vanishes under 4wd and reappears right away under 2wd. I'll check everything all you guys have mentioned and repost the results.

The front ujoints were replaced a couple years ago, so they should be ok

Thanks again, Dan

explorer, you were correct, it's the passenger side ujoint. It's only lasted about 30k miles, and has given up the ghost. Thanks for all your help!