Valve Knock 02 GMC 6Litre

GM 6 Litre:
Does anybody have a valve knock on initial starts after an overnite sit.
It id more substantial than a regular cold start knock. The dealer said it was normal. It doeas not sound normal, it almost sounds like someone is banging the block with a hammer. It last for about 2 minutes.

you have a lifter that is collapsing when it sits overnight the noise probally goes away after a couple of minutes. if new it should be covered by warranty if old its "normal" a small amount of hydraulic fluid added to the oil 2-300 miles before an oil change may cure it. if not try s.t.p. oil addative but put it in warm and run the engine 15 minutes before shutting it off.

Take a look at this Post


http://www.automotiveforums.com/vbulletin/showthread.php?t=147302