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bad engine knock! PLEASE HELP!!!

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by yeevveey211, Mar 16, 2013.

  1. yeevveey211

    yeevveey211 New Member

    ^ good point I parked my truck on a slight incline nose down . also I remember it rained a lot that night before my truck took a dump on me
  2. geo1

    geo1 Member 1 Year 100 Posts

    o.k. to j cats info on t.s.b,i just pulled my rear foam out,no big deal,it was shot,while there i felt valley floor,it was dry.yeha,i could only reach so far,but happy with results,now harness is right there for k.sensors,would it be wise to push/pull lightly to try for a better connection?they are a pop on connector,j cat?info?
  3. yeevveey211

    yeevveey211 New Member

    ok I'm stumped I really wanna figure this out . it's a loud knocking vibrating my whole truck and does NOT go away after warm up . first thoughts that pops in your guys head ?
  4. geo1

    geo1 Member 1 Year 100 Posts

    try pulling a spark plug,one at a time,and run it,this way you can isolate to a specific cylinder,otherwise pull off valve covers,look for valvetrain failure
  5. j cat

    j cat Rockstar 4 Years 1000 Posts

    so far all I get is you removed the plugs and put them back in. did you crank engine with plugs removed ? pressure test the fuel system for failure ? compression test ? measure plug wires for resistance to be all about the same .

    when cranking , engine plugs out, remove fuel pump fuse.

    with sound issues it is not easy over the internet to diagnose this .

    piston knock or ?????

    what plugs are in there ? who made them ? do they all have the same color ? how many miles on the plugs ? plugs can crack . if the water got on a hot plug or you dropped it this is possible.
  6. yeevveey211

    yeevveey211 New Member

    yes i did that still having the same knocking noise im going to pull valve covers off right now to check inside

    - - - Updated - - -


    yes removed the plugs they all look good not cracked they all have good spark. did not compression test i could test today. i also am going to pressure test the fuel today.
    i will check the fuel pump fuse today also
    i can try and get you guys a video clip or sound clip
    all the plugs are same color and do not see any signs of carbon build up or burned plug,
    i might as well replace them since i am going to the auto store to get a fuel pressure tester
  7. geo1

    geo1 Member 1 Year 100 Posts

    the reasoni think behind running it with one plug removed at a time is by taking pressure off components,youre basically removing the compression stroke to each cylinder,i would think the sound should change quite a bit

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    add to;you have ruled out a leaking injector,my run test would probably show a bottom end problem,but youre motor is shaking,so more likely top end (skipping)one other easy test is while running,press a long handle screwdriver to youre ear and other end to each injector one at a time and listen for clicking,might be helpful
  8. geo1

    geo1 Member 1 Year 100 Posts

    any luck finding anything?
  9. yeevveey211

    yeevveey211 New Member

    yes I pulled my Valve cover off and pulled rockers off and found a bent pushrod!!!!!!!!!!
    heres a picture

    - - - Updated - - -

    you think I have a bad lifter?

    - - - Updated - - -

    it stuck valve ? how can I check either ?

    Attached Files:

  10. j cat

    j cat Rockstar 4 Years 1000 Posts

    since you had no issues until a cold start then I would say the cylinder was hydro-locked. If all the rods are good and only one cylinder has the bent rods this would be a good guess.

    with a rod bent the plug should look bad. could be stuck rocker arm but on start up that would be weird with no warning prior to this. bent rod from over reving the engine with your short trip driving I can't see that .

    - - - Updated - - -

    you think the piston come off the crank ?

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