2005 Silverado 4wd

-5.3L vortec L33

-112,000 miles

- no after market mods other than exhaust work done early in trucks life (headers and true duals)

- regular oil and fluid checks/ changes

- besides a slight lifter tap nothing abnormal about drivability. ( faint lifter tap been ongoing for years)



En route to work one morning about .25 miles from the house, truck began making very noticeable knocking, I immediately turned around and parked in garage. Until I had time to diagnose problem.


upon inspection

- correct fluid levels

-oil pressure at idle (40lb) and holding

(oil pressure sensor replaced last year )

- sound seemed to be coming from passenger side toward firewall

-no noticeable shavings in oil

-DTCs (cylinder misfire, 02 sensor, fuel evap )



For the DTCs both fuel evap and 02 sensor has beentriggered for a year probably.


The cylinder misfire may have been an old code a month prior to this knocking from when my catalytic collapsed inside itself causing horrible drivability and totally restricted exhaust flow on PASSENGER side exhaust. This was fixed soon after cat collapsed (10 miles) to make it home

-removed catalyst

-welded exhaust back where catalyst was removed

- checked manifold gaskets

—- this may have caused cylinder misfire code to still be triggered



truck drove normally for about a month

after inspection I

——replaced —-

-head gasket

- lifters (hydraulic roller)

- push rods

- valve cover gasket

- intake manifold gasket

- new IR plugs (gapped)

- rocker arms left alone as were in good condition




upon reassembly and fluids topped off and oil primed through system before fuel pump fuse reinserted.

——

- truck started normal but knocking was still present.
- oil pressure normal

-cylinder compression test
showed 135lb ~2% on each cylinder

- oil and fluids normal



-all this has been checked at idle



- it seems like the knocking sound seems to dissipate as the idle increases though still noticeable.

As mentioned the knocking is loud, very noticeable at idle rpm. Haven’t driven it any distance and want to try avoid attempting to drive to mechanic (tow truck is an option but want to avoid throwing money away on something I can fix myself. )


- no codes are showing now after top end work I did.

But knocking is still present as it was before head work.


Any advice or suggestions on how to diagnose what else i could do to diagnose the problem. I have a code reader but nothing that will give live feedback.


New here so hope the is formatted and in correct forum to get some guidance on this problem. Love this truck and the L33 engine in it would love to get this problem resolved without an expense trip to a mechanic.

thanks!