Engine knocking

If it is knocking and no oil up top put a pressure gauge on it and see what it shows. The 5.3 oils the top end first so if there is no oil there it is not getting anywhere else. Could be sludge blocking the oil pick-up, scored pump or blockage farther in the oil circuit. If it has been run that way very long it will probably be a rebuild or replace type repair.

Good morning.

The first thing I would do is remove the valve covers and inspect the rocker arms. Sounds like you have a broken rocker arm. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed.

Roy

So is question to rebuild or replacement engine?

2 ways to do this, if it's a rod knock you can replace theengien with a rebuilt unit, or replace with what's called a crank kit that gives you a crank and all the bearings. However if any rods have had the bearing spin in them then those will have to be taken out and fixed. It depends on the damage. A good thing to test is on a small block with the engine not running, try to push the crank at teh balancer forward or backward with the belts off. If it moves far like a 1/8inch then your thrust is shot on the crank and that will need tobe redone. This is quite common on a small block. Good luck.

Could be spark knock try cleaning out the EGR valve and see what happens or the gas octane you're using

If the knocking noise is coming from the lower end could be rod or main bearings, at upper could valve lash-lifters, wrist pin or rings

Could be carbon on piston, piston, rod, main etc. Try pulling plug wires one at a time to see if knock goes away if it does then that is the cylinder to hone in on. If it stops it's either a rod bearing or piston problem.