I'm new to the forums and i must say this looks to be the best place for 6.5 info. The Truck in my Sig. has a rather hard Knock when idling at 650 -800 RPM's as soon as it revs past 800 - 900 its fine and the knock goes away .. I have Read some other post about crank pulley and Balancer they both seem to be ok .. I removed the belt to check the pulley and the noise is still there and the balancer seems to be in good shape .. Any other suggestions on what to check next??

Does the sound change when you put your hand on the turbo heat shield? Is your aluminum coolant line touching any injector lines? Injectors in good shape?...

All lines are good, I spent an hour looking at all the metal lines last night and I tried the heat sheild also. I really do not know about the injectors ... only had the truck for about 3 weeks . I did put a bottle of injector cleaner in to see if that helps.. i guess time will tell on that one. If it helps the noise I will look into changing the injectors. They LOOK fairly new, but they cleaned under the hood so good before i bought it I can't tell whats new and whats not.

Can you hear the knock more strongly in one area? If so, try changing injectors around to see if the noise moves along with them....

You can take a wrench and slightly loosen the flare nut at the top of each injector while the truck is idling. The engine will miss on that cylinder when you loosen the nut. If there is a problem with the injector the knock will go away when you have the nut loose. You can then pull that inector out and take it to a shop and get it tested fairly cheap.