Outboard motors draw water from inlet filters in the lower leg, usually in an area just above the gearbox. The water is drawn in by the water pump situated within the leg itself. The water pump is driven by the output shaft that connects the powerhead to the gearbox, and consists of a multi bladed rubber impeller rotating within a polished steel housing. The water is forced by the pump up a tranfer tube to the powerhead, where after circulating the engine, it exits through a calibrated drilling at the powerhead called a 'Pee hole'.

The first signs of water pump problems are usually indicated by low or no water output from the Pee hole. In checking out pump problems where no water is issuing from thr pee hole, the pee hole should first be probed with a suitably sized piece of wire, as the pee hole can easily become blocked by debris or corrosion. If the probing appears to indicate that the hole is clear, the next move would be to blow back through the pee hole with compressed air and check if air is exiting from the water pump intake vents, this is more obvious if the leg is in a water barrel, as bubbles will be created a the intake filters. If plenty of pressure is evident at the intake filters, then it is very likely that the water pump impeller requires replacement. The intake filters can also become very restricted by crustations if the bout is used in salt waters, so these should always be inspected and cleaned of any restrictions.

In some cases the rubber seals situated at either end of the water transfer tube can become perished, this can cause reduced water flow to the powerhead, or in extreem cases, no flow at all due the the quantity of water leakage at these points. The lower seal is easy to see and replace, but the upper seal can require the entire powerhead removal when replacing it.

NB: RUNNING OUTBOARD MOTORS FOR EVEN 1 MINUTE WITH THE PUMP INTAKE OUT OF THE WATER WILL DESTROY THE IMPELLER, SO DON'T DO IT!