Outboard-flushing the motor

I’m very excited about having my own sailboat. It’s nice to have one that actually works, and I’m kind of sad that I have to winterize it when I just got it.  Actually, I’m really bummed out.  I’m not a big fan of winter, especially since it’s cold and I can’t sail.  I also really don’t like how it gets dark so early.  I don’t think I’d ever make it up north.    Maryland is as far north as I ever want to live – actually, to be truthful Florida is as far north as I want to live.

I think you can pretty much tell that most of the time I don’t really know what I’m doing. I just kind of fumble through the best I can. I have very little experience with outboard motors, other than a few times as a kid when I was either a passenger or when I managed to sink a friend’s fishing boat and motor while trying to launch in a windy Lake. I have no experience operating or maintaining one. Come to think of it, I don’t have that much experience with boats either. Especially not a working boat. I have lots of experience with broken boots!

What I DO have is an attitude that pretty much no matter what it is, I’ll give it a go.  It’s really great that sites like YouTube and others offer so much “how to” advice.  There are many times where I don’t really know what to do but I just do some research and dive in anyway.

In this case I also have some experience with the motors on riding lawnmowers. People keep giving them to me or selling them to me cheap on Craigslist and somehow I managed to get them running. I’m hoping that experience will transfer to the outboard. A friend once told me that with motors all you have to worry about is compression, gas, and spark. If you have all those you are doing pretty good. I’ve noticed that with outboards you also need to make sure that you have a good outflow of cooling water while running.

To get ready for using and winterizing the outboard motor I have been reading the maintenance manual. Flushing the motor is not actually part of winterizing.  The maintenance manual recommends that it be flushed with freshwater after every use in salt water. I’m not sure if this is practical while it’s moored in the slip, but in the spring I’ll see about the feasibility of doing so.

When it is running, an outboard motor is cooled by sucking in seawater and running it through a heat exchanger then pumping the water back out. This means yucky corrosive salt water is running amok inside the engine.

Now that the motor is off the boat and on my handy-dandy new motor stand…

Outboard motor on motor stand

Outboard motor on motor stand

I can start running through my winterizing tasks. First on the list is flushing all that nasty saltwater out of it. The motor came with a nifty little device to go over the water intake and attach a hose to it.

Nifty Flushing Device

Nifty Flushing Device

The motor sucks in cooling water through little openings at the bottom of the motor.  These openings are usually under water.

Water intakes, this vent goes through to the other side

Water intakes, this vent goes through to the other side

The clamp slides onto both sides and covers up the intake vents so you can supply with water from a garden hose.

Device attached and ready to use

Device attached and ready to use

So I put it on, attached it to the hose, turned the water on and fired up the motor!

Flush in progress – see the top of the Catalina 250 rudder in the far right garage bay?

Since the stand is not made out of pressure treated wood I clamped on a large garbage bag to redirect the water. It worked pretty well. That’s a nice jet of water squirting out to the side of the motor so I would say it’s getting flushed pretty well. I’m guessing the impeller in the water pump is in pretty good shape too.  I let the motor run about five minutes to get a good flush.

Wow it felt great to see it running.  Somehow I had tamed this loud smokey mysterious beast to do my bidding – it felt a bit like taming a dragon.

After removing the hose and flush device I let the water drain out.  Then I tilted the motor to the up position and a bit more came out.

While it was running I unplugged the gas line and let the gas burn out so there is no residual gasoline in there. These are two tasks that should be done after every time the motor is operated. I’m going to start operating the boat on checklists until I get more comfortable with everything. Here’s the start of my first checklist:


  • flush motor with freshwater
  • unplug gas line and let motor stop on its own when it runs out of gas
  • Close vent in gas tank

So here is a question for my knowledgeable boat buddies out there. I was told to do the flush with nontoxic antifreeze using a bucket to hold the antifreeze for inflow and to catch the outflow. Since the water drains out (and it seems like it is completely drained out) there doesn’t seem to me to be any need to use antifreeze. Also, the maintenance manual only mentions flushing and doesn’t say anything about using antifreeze. Please comment with your thoughts. Thank you!


6 thoughts on “Outboard-flushing the motor

  1. I haven’t heard that advise before but it shouldn’t hurt anything to use it. I’m sure most engines are designed so that the cooling passages don’t hold a bunch of coolant even after being drained. That would be bad in places where they could freeze. The residual antifreeze film might help a little to prevent the seals and impeller from drying out. If it were important, though, I’d think the manufacturers would recommend it in their owners manuals. If used in salt water, I’d be inclined to once per year use a vinegar solution to dissolve any calcified growies and let it sit in all the passages overnight (or longer if there’s an accumulation) before flushing with clean water.

Leave a reply, would love to hear from you!

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s