Carl, I really can't figure out how an engine "going hydraulic" would do that sort of damage. It looks to me more likely that a) The valvestem broke, probably a fatigue failure. b) The valvehead rattled around the combustion chamber for a while, damaging the top of the piston, the head & the spark plug and possibly other valves. c) At some stage the valvehead got sufficiently jammed to stop the motor and posiibly displaced the head enough to allow water in through the head gasket. (IIRC there was water in the cylinder when the head was removed. It could have seeped in later anyway from the waterjacket. See if you can get a closeup photo of the break in the vavestem. Fatigue breaks are quite characteristic and if that's the root cause, you're off the hook. What you would be looking for is a series of arcs across the surface of the broken metal caused by crack progression. I'm sure there's some photos on the web somewhere (http://en.wikipedia.org/wiki/Metal_fatigue shows an aluminum piece with fatigue crack growth). Just an opinion of course!. RP 2008/8/19 Stephen D. Barnes : > Vitaliy wrote: >> Hi All, >> >> This is a continuation of the [EE] thread with the same subject. >> >> Carl Denk said: >> >>> Pictures would be worth a 1000 words. :) >>> >> >> http://www.maksimov.org/jetski/ >> >> Would love to hear your thoughts! >> >> Sincerely, >> >> Vitaliy >> >> >> > Dude, that is one kick a$# jet ski motor! ;-) > > -- > Regards, > Stephen D. Barnes > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist