Outboard motors are commonly used in boats and are designed to power vessels efficiently and effectively. However, to remain functional and prevent overheating, outboard motors require a cooling system that circulates seawater or fresh water.
Water cooling an outboard motor ensures that the engine remains at an optimal operating temperature, reducing the risk of internal damage due to overheating. So,?
The cooling system of an outboard motor consists of an impeller that draws water from the surrounding water body through an intake located in the lower unit. The impeller then pumps the water through the engine block to absorb the heat generated by the combustion process before exiting the engine.
Once the cooling water has circulated through the engine block, it exits through the exhaust system. There are two types of outboard motor exhaust systems – the two-stroke engines, which have a system similar to a car exhaust, and the four-stroke engines, which usually have a separate exhaust tube.
In two-stroke outboard motors, the exhaust system is designed to conduct the cooling water out of the motor through a small hole located at the rear of the engine. This hole is usually located above the propeller and is referred to as the tell-tale.
When running the engine, a continual flow of water should be visible exiting the tell-tale in a steady stream. If the stream of water from the tell-tale is interrupted or intermittent, it may indicate a blockage somewhere in the cooling system, requiring immediate attention.
On the other hand, four-stroke outboard motors have a dedicated exhaust tube mounted behind the cavitation plate. The exhaust pipe in four-stroke outboard motors is separate from the cooling water outlet and does not have any tell-tale.
In summary, fresh or seawater enters an outboard motor through the propeller housing or lower unit. The water is then circulated through the engine block to absorb the heat generated by the combustion process before exiting through the exhaust system either via the tell-tale in two-stroke models or a dedicated exhaust tube in four-stroke models. It is essential to ensure that the water exiting an outboard motor is flowing continuously and is not interrupted to prevent engine damage due to overheating.