knocking sound only while driving at low rpms

[95z71performer]

my 2000 silverado with a 5.3 (185,000 miles) is making a light knocking only when I'm driving and at low rpms I'v been told everything from an old motor that's on its way out to it could be my cv shaft for whatever reason because it goes away as I go faster as well

 

the truck also won't go over 4500 rpms while driving and sputters when it gets to about 4300 rpms I'm doing a check engine scan when I get the rear end back together to see if anything comes up from it's history

[95z71performer]

the knocking to?

[Jsdirt]

Nope - that's just 21st century GM for ya there ...

 

Without my hearing the knock, it could be anything from normal, to lifter noise, to piston slap, to rod knock from worn bearings.

[Jsdirt]

Noise seems to be an LS trait, from what I'm seeing ...

 

 

As far as not revving over 4,500, check your fuel filter first.

[95z71performer]

it will rev over without a problem in park or neutral but it won't do it while driving the last thing to do is my fuel filter so I'm hoping that will fix it

[Jsdirt]

That's a classic symptom of a filter packed solid. There's a high probability that that's your problem.

[95z71performer]

I'm going to hope it's nothing major because I don't want to have to dig into it to much

[95z71performer]

On just found oUT last night that the knocking goes away after its warmed up a bit and it almost sounds like a loose rocker or something inside of the valve covers

[00Silverado4x4]

This is what I'd do..

1. Double check all fluid levels (transfer case, trans, engine, differentials...

2. If you added anything, test drive, still has sound then...

3. Jack truck up and rotate everything using engine power and by hand

a. Try to reproduce and localize sound location (get a sound clip if possible)

4. From there if you still haven't found the problem, post sound clip for other possible ideas of what and where to check

5. If all else fails, unfortunately it will have to be taken to a shop or dealer to have diagnosed/repaired.