your impeller is located in the bottom end, theres 2 bolts holding the gearbox on, be gentle if they wont turn try some heat.once undone the box should just pull down, a plastic hammer may help if its tight. theres a copper water pipe running up to the engine, fix your garden hose to this and apply a little water pressure the water should circulate round the engine, if not you may have a block running round the head
shaun, February 2008