Loud CLunk

[mysteryincman]

I have a 2000 Sierra 2wd with the 5.3 V8 and everytime i start off from putting it into drive it makes a clunking noise same with if its in reverse then i put it into drive it makes the same noise. Has anyone else had this same problem, and know what needs to be fixed. Any help would be appreciated. Thanks in advance.

[tallguy1972]

If the clunk you describe is like mine, which sounded like a popping noise under the truck when changing form rev. to fwd and fwd to rev, it is very likely it is the transmission mounts(where it bolts to the frame). The noise only occurred when I started off. It seemed to occur mainly on the initial start in the new direction. I had one that was loose to the extent that it could only be picked up by the special tool they have at the dealer where they hook up sensors to certain parts of the truck and listen with a stethescope-like instrument. One of the techs there listened to what it was doing and predicted it might be the mounts. He verified it with the instrument. Took all of 5 minutes to tighten the nut on the mount.

[mysteryincman]

Yeah it is just like that thanks.

[GMCTech]

Most clunks are from two areas the leaf springs (spring slap) or the driveshaft splines.

First, take your driveshaft out and grease (with thick lithium - not spray) the driveshaft splines real good.
If that's no helps, get a set of leaf spring rubbers (they slip over the helper spring ends)

One of these two things should fix the concern. You can check the tranny mounts too, but I have yet to see that be the issue.

Hope this helps.