Overheating Boat Motor: 4 Possible Causes

Posted on: 17 May 2017

If you notice that the motor on your boat is running hot, it is important you investigate the problem. An engine that is overheating could fail or pose a fire risk. Below is a guide to 4 possible causes of engine overheating.

Broken Temperature Gauge

The first thing you should check is that the engine is really overheating. If the temperature gauge becomes faulty, you may see a false reading that suggests the engine is running much hotter than it actually is. To avoid making an unnecessary trip to a marine servicing yard, you should carry out an independent test of the engine temperature. To do this, you simply need to use an infrared thermometer to measure the temperature of the engine when it is running and then compare the reading on the thermometer to the reading on the temperature gauge. If the gauge is faulty, it will need to be replaced. If the gauge is working, you will need to carry out further investigations into the cause of the overheating.

Blocked Drive

Over time, algae, seaweed and other debris can begin to build up on the engine drive. When this occurs, the flow of air into the engine can be disrupted, which prevents the transmission of heat from the motor into the surrounding atmosphere and results in overheating. You should carefully access the drive and check that it is not blocked. If you discover any build up on the drive, you should clean it down using warm water and soap.

Malfunctioning Impeller

Some boats are fitted with an impeller. An impeller is designed to allow cold water to flow around the engine. This flow of water helps to transfer heat away from the motor, keeping the engine system cool. Over time, the impeller can be affected by wear and tear, which can cause the moving parts to malfunction. If your engine is overheating, you should check that the impeller is in good working order.

Leaking Radiator 

If your boat engine does not have an impeller, it is likely that a radiator will be used to keep the motor cool. Radiators are often found on sea boats as this setup prevents salt water from damaging the engine casing. If the radiator has started to leak, it will no longer effectively cool the motor. You should inspect the radiator for signs of leakage. Staining or rust on the outside of the radiator is a classic sign of a leak.

If you are having problems with the engine on your boat, you should contact a marine service today for further help and assistance.