Your cooling system is an important feature of your boat, and one you probably don’t think about much, especially if you have an open cooling system. After all, the water is keeping your engine cool pretty much all the time, so how hard could it be to maintain a boat cooling system?

If you do it right, not very hard. That said, it’s still very important to know how to maintain a marine cooling system to make sure it doesn’t fail you at a critical moment. Here are some useful tips on maintaining the cooling system on your boat.

Marine Cooling System Maintenance Checklist

Make sure you:

Check coolant/antifreeze: Even in an open cooling system where the seawater does a lot of the cooling, antifreeze plays a critical role. As part of your daily maintenance, you should be checking to make sure your coolant is at the correct level and topping it off if necessary.

Inspect the header tank: At least once a week, you should have a look at the coolant level in the header tank or overflow bottle. Make sure the coolant is the right color and consistency. If it’s not, you’ll need to replace it.

Flush the anti-siphon valve: Once a month, flush out the anti-siphon valve to make sure it isn’t clogged.

Drain coolant/antifreeze: You should drain and replace your coolant at least once every two years.

Clean out heat exchanger end caps: You should remove your heat exchanger end caps, make sure they’re still functional and clean them out at least once a year.

Change anodes: For the heat exchanger of our marine cooling system to work properly, you’ll need to change your sacrificial anodes regularly. Heat, coolant and seawater combine to put a lot of stress on metal, and regular replacement of the anodes will go a long way toward protecting your system. In most cases, you’ll only need to change your anodes once or twice a year. However, you should remove and inspect them every month to make sure.

Maintain your raw water cooling system: To make sure your raw water cooling system continues to be in good working order, in addition to flushing and cleaning the syphon break at least once or twice a year, you should clean the thru hull of marine growth, make sure the seacocks open and close smoothly and inspect the raw water strainer, pump and impeller for wear, holes and other defects.