1998 Front End Noise

I have a 1998 Blazer 4x4 V6 Vortec w/ automatic transmission. A few days ago on drive down the highway I noticed a clicking noise coming from the front end. The faster I went the quitier it became and the more I slowed down the louder it got. When I stop completely it stops making the noise and when I go in reverse it doesn't make any noise at all. Also once it starts making the clicking noise if I put it into 4-wheel drive it goes away and then after I take it out it doesn't do it for long period of time. I had a mechanic look at it today and he found no problem the car never even made the sound. Then on the way home from work it did it again. I stopped put it in to 4-wheel drive and it wnet away and then started again by the time I pulled in the drive way. I'm just not sure what it could be. C/V joint? But wouldn't it do it all the time then? The clicking noise makes no differencewhen I turn the wheel. Maybe it something to do w/ the spline? I'm not sure. Has anyone had something similiar happen? I just wonder if there is some kind of common problem. I would really appreciate any help anyone could provide--Thanks!

sounds like the problem except I have a humming noise. A cv joint should get louder on turns, is the noise come from l/f, r/f or center? If you jack it up and rotate the wheels can you hear any noise?

Does it still make the clicking noise when you let off the accelerator?

Could be the valve lifter (i think its called that?) reacting to the higher thickness of your oil because of the weather.

My 2002 Blazer started doing the same thing at the tail end of a 2,000 mile car trip (yesterday).

The noise (clicking/popping sound) mine makes is coming from the left front end of the Blazer. It does not necessarily happen when I turn the vehicle. When jacked up and the wheels are rotated it does not make a sound. Took it to a mechanic on the road, and they searched for something loose and couldn't find anything. Of course, when the mechanic got in to drive the Blazer, it didn't make the sound at all. However, this morning on my way to work, it clicked and popped as soon as I exited the highway. Please someone help!