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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

    well that's what I'm feeling is the piston misfire . I'm thinking my lifter is bad.i couldn't see that my cylinder would be hydro locked . I'm going to soak some b12 chemtool down all the lifters and do a engine flush to clear this up. I also noticed my spark plug was wet . unburned fuel noticed big time .
  2. j cat

    j cat Rockstar 4 Years 1000 Posts

    when a rod is bent that much you have more than a lifter issue. the piston wacked that valve which bent that rod. Hydo-lock meaning the cylinder when sitting shutdown for a time filled with a fluid. then on starting the valve pushes so hard on the rod, it then bends.

    or the piston breaks off and wacks the valves bending the rods. if this is only ONE cylinder this is what / why I think this is the cause.

    in any case the engine will require a breakdown to inspect the cam. see what else got damaged.

    you could try to just put another rod in see what happens.
    Last edited: Mar 27, 2013
  3. Backroads

    Backroads New Member

    Well I started to disagree with j.cat but what is done is done and all that can happen is you lose another lift rod, but I would bet on internal damage that means a teardown plus I would wonder when the darn thing would turn loose again.
  4. yeevveey211

    yeevveey211 New Member

    yep decided to pull the motor checked the top if piston and she's scored and piston has turned in the cylinder . so only thing to do is to pull the motor. I have a local engine shop that are Awesome old schoolers that rebuilt my older brothers trailblazer ss . so I'm going to do as much as I can then send her there for a complete rebuild
  5. j cat

    j cat Rockstar 4 Years 1000 Posts

    the piston breaking off the crank is not all that common with these engines.

    It is possible though the hydro lock issue may have caused this . also if the piston rusted to the bore. the pistons rusting to the block is a common problem with over wintered boat engines.
  6. yeevveey211

    yeevveey211 New Member

    how would a piston turn inside the cylinder? the markings are all in line except that piston
  7. j cat

    j cat Rockstar 4 Years 1000 Posts

    since the piston rotated you should be able to pull it out .crank the engine see if the piston goes up/down my guess is no.
  8. geo1

    geo1 Member 1 Year 100 Posts

    great god,still thinking a leaking injector is at fault?sorry to hear of this news,no way telling when turning the key
  9. yeevveey211

    yeevveey211 New Member

    ya not fun I have everything off ready to pull out as soon as this weather is nice. I guess another bump in the road you gotta go over . keep ya guys posted

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