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-   -   Breaking in new rebuild (knocking) (https://www.truckforums.com/forum/chevy-silverado-gmc-sierra-forum-11/breaking-new-rebuild-knocking-12214/)

88GMjack Nov 28, 2009 03:40 PM

Breaking in new rebuild (knocking)
 
I have just rebuilt a 350 engine for my truck. The bottom end was done at a machine shop. Heads,push rods, roller rocker arms, intake, valve covers were installed by myself.

the problem I'm having is when I turn the engine on to break it in, theres a loud banging/knocking noise coming from the engine. It's more then a loose or sticky rocker arm ticking. The noise does increase as rpm goes up. I checked the PSI (compression) on it and the #2 cylinder has about 175 to 180psi compared to all others at a 150psi. Also the header tube on the #1 cylinder is cold when all others are warm/hot.When checking all the plugs they all have signs of ignition.

I'm not sure what it could be right now, either a bend push rod or maybe the rocker arms could be hitting the valve cover's which are aluminum so it might make a louder noise but it definatly sounds like metal on metal contact somewhere. Any help or ideas would be great!!!


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