I got a new knock:(
 

My truck has a knock now and sometimes it's very distinct and sometimes it's very faint. But it only happens when at an idle. My dad thinks it sounds like a valve knock because a rod or piston knock wouldn't go away with gained RPMs. Got any idears? And I also got my fuel pump is ticking behind the cab, does that mean it's going bad?

Your lift pump would be my first guess as to the knocking sound ... mine does this when its real cold or real hot out side ....

Ok thanks! I'll give it a closet look next time I hear it.

check your valve lash as well easy fix and will really cut back on some knocks

Ok update on the knock, it started doing it on the way home again, so I pulled over to get out and listen. The sound was very loud inside the cab, but when I got out, I could not hear it at all, anywhere. Got back in, it was still knocking, so I got down in the floor to listen, it honestly sounds like the transmission is knocking(NV4500). I also noticed that it went away when I pushed the clutch in. I'm thinking something in the trans is bad. Anybody ever heard of one doing that??

yeah, it could be a lot of things in there ... could drain the fluid, remove the inspection plate and see whats goin on

ohhhh ... yeah not a good thing .... hopefully its a cheep n easy fixer..:c: