Turning truck off big clunk

[Chevysilver0195]

I know it's usual for a diesel to stop and have a little clunky but mine has gotten worst what can it be

[DmaxMaverick]

Depends on the "clunk". Could be engine mounts, tranny mounts, exhaust system (hangers/brackets), accessory drive dampener, accessory, other plumbing, etc. Pretty much anything that moves or may move, whether it's supposed to or not.

[Robyn]

Check the serp belt pulley and make sure the rubber ring has not broken loose.

The pulley is mounted on a bearing and then has a bonded rubber drive ring.

If the ring breaks loose they make terrible noises

[trbankii]

I’m going to go with the beginning of Dmax’s list. The pulley rubber is likely going to be making noises while running, not just a big clunk when it is shut off.