It is vital that your boat engine is well-maintained and trouble-free. The last thing you want is for your engine to fail whilst you are out at sea! A boat without an engine can quickly drift far out with even a mild off-shore wind or current.

When I bought my first pre-owned speed boat, I bought a manual for the engine, intending to carry out routine maintenance myself. But I’m not mechanically-minded and when I read what was involved, I decided to leave it to the experts!

So unless you know what you are doing, I recommend that you have your boat engine regularly serviced by a qualified marine engineer.

Boats are usually only used during the summer months and are not used during the winter. To protect it from damage during the cold, damp winter months, your boat should be “winterized” after using it for the last time that year and then “de-winterized” before using it for the first time next year. The engine should be serviced at the same time as it is de-winterized.

Boat engines are water-cooled. When the engine is running, impellor’s draw water in to the engine. This water circulates around the engine, keeping it cool by absorbing the heat and then escapes as warm water through a small hole near the top. The jet of water escaping is called a tell-tale. If it isn’t there, it means the engine is NOT being cooled and will over-heat which can cause irreparable damage. So you MUST turn the engine off IMMEDIATELY.

NEVER run a boat engine out of water. Even if you run it for a few seconds, the engine itself may not over-heat sufficiently to get damaged but the impellor can quickly over-heat and become damaged so that it won’t be able to draw sufficient water to cool the engine next time it is run in water.

 It is important to flush the engine out with clean water after it has been used in salt water as salt water is very corrosive. Newer engines have a water inlet that you can connect a hose to, turn the tap on, start the engine and it will draw water through to clean the inside of the engine.

Older engines don’t have this, so ideally you should have some sort of water tank that you can submerge your boat engine in if you want to run it when the boat is not on the water. I managed to find an old plastic central heating expansion tank for sale on eBay that was the perfect size for running my boat engine in. It only cost me a few bucks!

If you don’t have a suitable tank, and you want to run the engine when the boat is out of the water, perhaps to flush out salt water, what you can do is cover the water inlet holes with flushing muffs (sometimes described as “rabbit ear” muffs) attached to a hose. Turn the hose on, then start the engine and let it run at idle speed for a few minutes. Look for the tell-tale jet of water which shows that water is being drawn into the engine and circulated around it. After a few minutes, turn the engine off then turn the hose off.

I made this video showing how to flush clean a boat engine …