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5.7 unknown isues.....

  1. Gravzy
    Gravzy
    Has any one else experienced a knocking issue with there 5.7? I own a 2005 Z71 with 87000 miles on it. I started knocking so I immediately changed plugs and wires. Quieted it down some but it now seams to be coming from the lifter area. I havent experianced any oil pressue drops or increases. The only code that comes up is Bank 1 and 2 lean. Hopefully someone else has experienced this and can point me in the right direction.
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  2. murdog94
    murdog94
    in 2005 they only came with a 4.8L or the 5.3L. lifter noise is prevelant in these motors.
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  3. Gravzy
    Gravzy
    Ya ur right, my bad it is a 5.3. My 99 was a 5.7. I know the lifter noise is prevalent however this is heard over the lifters like maybe a rocker or something. Is there any tests I can do to pin point where the noise is coming from?
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  4. Silverado Junkie
    Silverado Junkie
    It could also be knocking from the pistons because a piston is slightly smaller than the cylinder when cold and expands as the motor warms up. The slap is caused by the piston moving side to side because it hasnt expanded to the proper diameter.
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  5. murdog94
    murdog94
    with out really pulling the motor apart i dont know.. I know that i use the screw driver trick to pinpoint where my lifters are ticking.. Also what type of oil are you running. Stepping up to a bit thicker will help to fill that gap that is usually caused by such loose tolerances that these motors can be built to..
    And reading your first post.. Bank 1&2 Lean needs to be taken care of since the knock you hear could actually be detonation that can lead to Motor Failure... So start there then if the problem still exsits then Look at other causes....
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  6. Silverado Junkie
    Silverado Junkie
    If your gonna change oils, start adding Lucas Oil Stabilizer to your oil. It cant be beat.
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  7. caddiac
    caddiac
    I went to 20W40 and the piston slap is all but gone in the winter months which is the only time I use to hear it anyway.
  8. murdog94
    murdog94
    Any further updates???
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  9. Electro
    Electro
    Harborfreight has cheap stethoscopes, for under $10 bucks (maybe 5 or 6). They have an extension that you place on the valve cover. I bet you could narrow down where the sound is coming from with one of these.
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