Yamaha 4-Stroke Outboard Water Pump Housings

The Yamaha marine 4-Stroke outboard water pump housing has a weep hole: a small hole that allows any coolant that may be leaking from a faulty seal to escape, thereby preventing it from becoming trapped and forced into the water pump bearing assembly.

The weep hole is just a few millimeters in diameter and is located on the top, side, or bottom of the Yamaha marine water pump housing unit between the hub and water pump seal. Water is drawn into the water pump through the intake opening of the lower unit, where it passes through a cavity that ends up entering the pump itself. At that point, the impeller pressures the water into the long inlet tube leading to the bottom side of the powerhead. The water pump, also known as the coolant pump, is the heart of the engine’s cooling system. It is the water pump’s job to regulate the coolant flow rate, and to constantly circulate coolant throughout the engine and cooling system. The water pump housing impeller enables the boat to use the water where the boat is floating in. Regular replacement is neccessary to avoid damaging the engine by overheating because of insufficient cooling or because of broken impeller parts being sent to the engine. When an engine overheats, you might think that the logical move is to help it to cool down by adding coolant. While this is a well-meaning move, it actually causes more harm than good. This sudden and rapid cooling cause a thermal shock and can crack the housing of the water pump.