Knock knock
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TECH Apprentice
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Joined: Sep 2005
Posts: 324
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From: College Station
Knock knock No one can figgure this out. My engines common case of "cold start knock" has progressively gotten worse in the last few k miles. This "slap" does not go away untill around full operating temp. not the "15 seconds" that the Gm service tech buliten reports. Although the sound is consistant with the piston slap, it sounds like it could be valve terrain, maybe a few lifters that arent building oil pressure. If I rev the engine a quick 2-3 times the knock goes away, i think, because the oil pressure rising with the RPMs' causes the lifters to fully pump up and the slack/noise is gone. I need to know what I need to do to make 100% sure that its is/isnt the lifters. DO I have to remove the Heads? thanks for any help.
