WATER PUMP KIT 391741

Function and technical context

The water pump kit is the central component of the water cooling system in 2-stroke outboard engines, responsible for driving the flow of seawater through the engine block to maintain the working temperature within safe operating ranges. This kit, reference REC391741, is designed specifically for 40 hp 2-cylinder engines in Crossflow configuration with exhaust through the cavitation fin and two-piece tail, including those that incorporate a half-moon key on the drive shaft. The pump works directly coupled to the propeller shaft by means of said key, so any deterioration of the impeller, casing or seal causes an immediate reduction in the cooling flow, with the consequent risk of engine overheating, melting of the cylinder head or serious damage to the pistons and cylinders. Replacing the complete kit guarantees that all wear elements are renewed simultaneously, avoiding secondary failures due to aging components.

When to replace this part?

The most common symptoms of a water pump kit in poor condition are the absence or reduction of the discharge water jet through the control nozzle, the temperature alarm activated during navigation and, in advanced cases, smoke or a burning smell coming from the engine compartment. The rubber impellers of the water pump are recommended to be replaced every 200-300 hours of operation or at least every two nautical seasons, since the rubber loses elasticity and the vanes crack even without prolonged use due to the effect of heat and salt. Performing preventive replacement on a scheduled basis, taking advantage of seasonal maintenance, is the most recommended practice to avoid a serious breakdown at sea that can result in a costly repair of the engine assembly.

Compatible Johnson/Evinrude Engines

Equivalent manufacturer part numbers