Re: OMC 5.7L loss of power
i have a freind with 5.7 omc similar complaint, engine runs fine no load, ran compression test all cylinder 165 psi to 180 psi, had replaced plugs, wires, cap,rotor, even carb.,checked fuel pressure all fuel lines chaek valves hoses
etc, even went as far to check cam timing all ok no slack in timing chain, pulled valve covers to inspect valve train movement all seam fine, i was hoping to find a worn camshaft, when using vacume guage engine has strong
steady vacume round 18 inches at idle, under load 2800 rpm vacume drops to
about 12 to 14 but engine/boat wont get out of its own way. even tried going from a 17 pitch to 15 pitch no change, next i am going to remove exhaust manifold and inspect flappr valves to make sure they are not stuck causing excessive backpressure but i would thing vacume guage would go into a positive reading if this was the issue. this engine runs like it doesnt have any compression as if rings were shot but no blow by, no oil consumption, i havent done a cylinder leak down test yet but i am sure this is going to be my next test, i dont know what to tell you folks but i am diligent and will let you know what comes up when i continue to diagnose when the ice has cleared this season, anybody who has any suggestion please i an open to all input, this seems like a common problem with this engine, please note this engine also had an breakerless ignition installed , it almost feels like my boat when i have all of my fat buddies sitting in the back and have to move them up front to get my boat up on plane, but i already had 2 of my large buddies ride in front of this boat and still no good , anxiously waiting for any input, thank you rodb267.
