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Old 14 August 2012, 15:30   #11
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Quote:
Originally Posted by jsrmacleod;
....what damage occurrs when theres a lack of 2 stroke?
Piston damage and bearing damage but the ball races and bigend rollers will survive with remarkably little lubrication. The more common problem would be overheating and a seizure or partial seizure where the engine tightens up and stops. If this has happened and the engine has cooled and freed itself, there would likely be a knock caused by piston slap. It is a kinda hollow knock and can often be louder under light load where the piston is not held hard against the cylinder walls by pressure. You sound as though you want it to be the engine. If, as you said, you can turn the prop while the engine is in gear but the engine doesn't turn, sort that first.
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Old 14 August 2012, 17:53   #12
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Consider some of the smaller mercs allow the prop to free wheel..so the gearbox may be fine...

Of course it could be shot. Also that on steves 250 we were all convinced it was the engine making a grim noise but it was just the way the noise moved up the leg from the box in the end.
Just trying too be optimistic for you..
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Old 14 August 2012, 18:53   #13
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Get it running, pull the deadman. The freewheel talked about above will rattle merrily until you come to a halt. My 70s Merc does it. Was in a mate's rib trying to empty a few litres of last year's fuel. The Tohatsu was like hitting a wall without it when we ran out...
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Old 15 August 2012, 11:11   #14
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You really need to volunteer more information. Also a sound bite of the noise would help.[/QUOTE]


Sound bite! I'm no more a computer whiz than I am a mechanic, I've got my mechanic pal coming to have a look tonight, we'll do a compression check and get his bore scope in to have a look to see if there is anything obvious, the general concensus is that its small end bearings, the compression check should let us know if the rings have gone.
I've checked the gear box on the other boat, its prop will turn one way by hand when in forward, my one does the same but when in reverse???? dont think there is a problem there though, deffo an engine knock, I'll try what was suggested, removing a plug ground it out and fire it up to see if the cylinder goes quiet, whatever it is, its a strip down for sure
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Old 16 August 2012, 07:09   #15
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Compression check carried out, the cylinders range from 125psi to 110/115psi so not a big difference, never did the bore scope, weather was very poor
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Old 12 March 2013, 08:40   #16
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Just a long awaited update, it was piston slap, replaced all three pistons and honed the bores which weren't too bad, now just about run back in, going well Fresh coat of hypalon paint and she's looking like new

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