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Cracked Piston

C

Commodore Dewey

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"Not sure if it was caused by

"Not sure if it was caused by carb, ethanol, crossed wire or advanced timing but all were discovered prior to compression test. 0 on the gauge for #4 cylinder all others at 135. Pulled the head in hopes of finding a bent or burned valve but 1/8 top of the piston is cracked and missing. Bore does not appear to be scored but there is some metalic debris at the very top of the cylinder. Less than 400 hrs on this rebuilt engine. Can the piston be pulled on while the engine is still in the boat? Can the bore be cleaned up and honed or does it need to be pulled out and completely machined? Thank you!"
 
"The motor has to come out, so

"The motor has to come out, sorry. If you're really lucky the wall will clean up with a light hone job. If not, it'll need to be bored oversize.

Do any of the other pistons look like they are damaged?

Jeff"
 
"Did you replace the manifolds

"Did you replace the manifolds and risers when you did the rebuild? If not, that is likely the culprit. Be sure and replace them this time."
 
Exhaust manifolds and risers a

Exhaust manifolds and risers are not the culprit. Timing error and a crossed wire I am sure are. Do either of you know what the difference between a crusader piston and Sierra or Federal other than $100?
 
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