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Discussion in 'Chevy C/K Truck Forum' started by cobra2end, Nov 13, 2010.

  1. cobra2end

    cobra2end Rockstar 100 Posts

    Ok so i have been told its normal with gm v8s that when you first start them to have a knock knock knock sound. does any one else have this issue for its starting to drive me nuts. nothing worse then going out after work and starting truck and having it sound so bad. A friend of mine has a 99 with the 5.3 and his does the same thing knocks till it warms up any idea
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    If it is a knock, it is bad, if it is a tick is the lifters and very common with the vortec motors.
  3. cobra2end

    cobra2end Rockstar 100 Posts

    any ideas on how to get rid of it i tried running z max and WILL NOT do that again my truck started eating oil like gas got that to stop with restore and 5 oil changes later
  4. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    Well how many miles do you have one it? because you could try going to synthetic oil, but more than likely its just a deal with it thing.
  5. cobra2end

    cobra2end Rockstar 100 Posts

    its got 162 and some change. i does not do it right after oilchange. take prob 10 starts and a few trips to do it. started running edge oil and all it seems to do is run out the cooler lines faster.
  6. stephan

    stephan Rockstar 3 Years 5000 Posts

    I think what you are experiencing is "piston slap" when cold & during warm up. If it was the valve lifters it would go away within a minute or so. Knocks that last until warmup is pistion knock/slap due to composition & style of pistons. GM knows about this & there have been many GM technical bulletins & many are posted on this site. Use the "search" function at the top of the page & enter "piston slap", "piston knock", "engine knock cold" etc. There are many good write ups previously on this site about your problem.

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