"Alisdair Gurney" wrote in message ...


Two suggestions:

1. Take off the water pump and examine the bronze bit that fits inside the
engine block for wear. There are three bolts attaching it to the engine
block and it's easy to remove (you don't need to take off the front of
the pump with the impeller). I had a similar sounding knocking problem
a couple of years ago when the large nut holding the governor in place
loosened and bits were moving more than they should, occasionally
catching the water pump where there's now a small flat spot.

2. It's normal - at low speed, say less than 1000RPM, they ARE clanky.
It seems to be just above the stalling point where there's little or
no energy left in the flywheel when the fuel combusts.

Alisdair

Alisdair,

Thanks for this. After talking to Jim at Cellar Marine we came to the
conclusion that the problem could be a sticking injector. I stripped
and cleaned the injector last night and it seems to have stopped the
knocking, although I have not run for an extended period.

I can only conclude that the injector nozzle was sticking open when
hot resulting in early injection of fuel and severe preignition
knocking.

Hopefully problem solved.

Phi