Outboard Engine Parts

Boating Know How
Flushing Outboard Engine
How to Flush your Outboard Engine (Video)
Video presentation on how to flush your outboard engine after each use. Presented by Honda Marine. ... read more

Video Transcript

So here we are, we spent a day in salt water in our Boab boat. It’s important now to wash all of the salt from the exterior of the boat and the exterior of the engine. But more importantly what we need to do is flush the cooling system. And the reason we flush the cooling system is that modern-day outboard engines and outboard engines in general draw water from the lake, from the sea and circulated that water around the power head through the cooling chambers and use that water to cool down the engine. So it’s important now that we have stopped the boat to wash out that saltwater because over time that salt could crystallize and could start blocking the cooling system passages.

And the way in which we do that, I’ll just put this hose down. Is we use a flushing attachment and this is called a set of earmuffs or rabbit ears. And we grab this flushing attachment and we put this flushing attachment over the inlet at the bottom of engine, as the bottom of the outboard casing. So we put this over and make sure that it’s nice and secure and that it fits completely over the engine water intake at the bottom here. We then grab our hose, now this hose is pressurized so I’ll just kink it over quickly and grab our hose. Attach the hose to the flushing attachment and make sure that we’re getting clean water flow over that inlet.

So now we’re ready to flush our outboard. We have water to the engine, and I would hop in the boat normally and kick the engine over. But I’ll get my trusty assistant to give the engine a quick start. So now the engines running, it’s important to ensure that there is water flow from the engine and we do that by looking at this telltale which indicates that water is now streaming through the cooling system. This is fresh water and it is not flushing our engine.

Normally flush the engine for 10 to 15 minutes, maybe a bit longer. You have to ensure that the thermostat fully opens, the engine gets to operating temperature so that the maximum water flow is circulating through that cooling system; circulating through all of those little passages and chambers to flush out the saltwater and those salt crystals. Don’t leave your boat unintended while you’re doing this. Because if the flushing attachment becomes loose, then you won’t have cooling to your engine and your engine could overheat and potentially do some serious damage.

So that’s the basics of flushing the engine. It’s important to do that after every trip in the saltwater and also in the freshwater especially if you have been show some mod and some sand and they might be some silt through the cooling system. So I’ll just switch the engine off quickly now and we’ll go through some other flushing ports on the other side of the engine and we’ll briefly wrap-up the flushing process.

Sometime it’s not practical or viable to run your engine. So if you’re coming home from a fishing trip late at night or early in the morning you can’t always run your engine. And some of these modern-day outboard motors have a secondary flushing attachment or a flushing port like on this Honda. We have one up here. This is not as efficient as drawing the water through your cooling system because you’re not getting your thermostat open and the thermostat working. However this is a good second alternative if you can’t run your engine.

So we usually grab the hose and you just connect the host of this flushing attachment, run the hose and let the water pressure circulate water through the cooling system; a good alternative if you can’t run your engine at night. Also on some of these smaller engines now they have a small gear case that sometimes have trick little flushing inlet ports. And what you can do if you can get the set of earmuffs over those is you can just stick them in a large bin or a bucket or even a canvas flush bag. You fill the bucket up with water, lower the engine into the water, start the engine and it will draw water through the cooling system and circulate the water so the cooling system appropriately.

So that’s an introduction to flushing your engine. It’s important to do so after every trip in the saltwater and I would do it after every trip in the freshwater as well just to get into a pattern to retain. That will make sure that your cooling system is flushed, you don’t have salt crystals or grit in your cooling system and hopefully ensure smooth running of your outboard for a long time.
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