First off, this is my first post so go easy on me. Now my truck (91 Pickup 3vz) has been making this noise for about a month or so now and i cant figure out what it is! it sounds like little pieces of metal clinging together and it doesnt do it when in 4wd. i have noticed that the drivers side cv is loose but that is common? Here is a sound clip https://soundcloud.com/tgm-17/untitled Any ideas?

 

Not a great sound clip. But if it only does it in 2wd, I would start by examining the hubs. Are they auto or manual hubs? And I don't believe the axle being loose is normal. What do you mean by loose? Like you can move the outer joint around? How does it compare to the other side?

 

The hubs are auto locking, and if i grab the cv axel it has about 3/4 to an inch of horizontal movement on the outer side whereas the passenger side has no movement. Sorry for the bad clip i forgot to mention that it only does it above 20mph.

 

Probably not. You probably have ADD (automatic Differential Disconnect?) which disconnects the 1/2 shafts at the differential in 2wd. This means the 1/2 shafts turn with the front wheels in 2wd.

There should be no perceptible movement at either end of the 1/2 shaft, as you see by comparing your suspect one to the passenger side. You've probably broken the outboard CV joint.

You can disassemble the 1/2 shaft, but what's the point? A rebuilt from Autozone is about $65. But a word to the wise: before you replace it, read up here on how to do it. Quite a few log in after they've gotten stuck and beat the hell out of their truck in order to get the half-shaft out. You don't need to do that.

 

You are right about the diff disconnect, although it is strange because if i shake the axel it does not make the sound that i am hearing. i can really hear the sound through the passenger side window especially if i am driving next to a wall or a curb. is it possibly a wheel bearing? the front right wheel has no play in it. Also just took it for a drive in 4wd and it only makes the sound when its not under load.

 

Definitely worth checking the axle. That doesn't seem right.
Again, can't really hear it so I'm just guessing. If you lightly step on the brake pedal while its making the noise, does it continue to make the noise, or does it quiet down? I had a nasty click noise in my truck for a while that turned out to be a broken spring clip in the caliper. Brake pads were rattling.

 

Breaking does not affect it :/ i can try to get a better recording but i can hear it pretty good through my headphones. i will get those axels checked out but i do not think its the source of the sound. The rattling starts at 20 and does seem to get "faster" as i speed up. i honestly have no clue what it could be. i have never heard a vehicle make such a noise.