Cooling System Maintenance

Cooling System Maintenance

Cooling 1

Keepin’ It Cool

Your boats cooling system is basically the life blood of your boat. If it’s not flowin’, you’re not goin’. Anywhere.

So keeping everything flowing as it should is critical to not only yours, but to your boats performance as well.

The following should help to keep everything up and running as it should so that not only you, but your passengers as well can enjoy yet another pleasurable day out on the water.

Cooling 2

Pump Up The Volume

Impellers, thermostats and water pumps are essential components; they regulate efficient working temperature in your marine engine. Marine engines invariably use the sea water surrounding the boat to cool the engine.


If it is raw water cooled, i.e. passing seawater directly through the engine, it will inevitably require service. Other system types use the cooling effect of sea water indirectly via a heat exchanger or keel cooler.
Cooling 3
Regardless of type, simple routine maintenance of cooling systems will assure your vessel is ready for its next adventure.
Good habits and preventative maintenance are your best ally in keeping the engine running at peak performance. Raw water systems like those on outboard and i/o engines should be flushed on the trailer after each haulout or at minimum, the end of season.
Flushing out seawater can be improved with salt removal detergents added into the water supply. Failure of these components will overheat an engine, possibly leading to costly damage of core components.
Water pumps with rubber impellers burn out if run dry. This could be caused by simply forgetting to open a seacock. Another common cause at sea is weeds or a plastic bag stuck in the seawater intake through-hull. Having spares on hand is highly recommended. As impellers age they lose there flexibility and should be replaced.
Cooling 4
Also, if your boat has been sitting dormant for any length of time, the impeller ‘blades’ have a tendency to hold that shape and once underway, they won’t “open up” to create maximum pressure and flow. Therefore, they should be replaced for maximum efficiency.


The thermostat is a simple valve which opens once the engine has warmed, thus allowing the coolant to circulate.
Cooling 5
On most engines the thermostat will pop at 160° F and be fully open at 180° F. To troubleshoot, remove a suspect thermostat and place it in a pot of boiling water with a thermometer.
A malfunctioning thermostat must be replaced. And the old wives tale of simply removing the thermostat altogether is a recipe for disaster.
By doing so, you are removing the ability for critical parts of the engine to warm up to property operating temperatures, creating not only an environment for increased wear and tear. But also premature failure.
Both of which can leave you stranded.