How to Winterize a Small Outboard

Let’s say you run your small outboard in salt water all summer and don’t flush it as often as you should during the season. (For a lot of us who leave our boats floating the whole time, that means never, not once.)

Time to rake leaves and winterize engines. This 8-hp Merc is standing on its skeg in a barrel full of clean fresh water.

Time to rake leaves and winterize engines. This 8-hp Merc is standing on its skeg in a barrel full of clean fresh water.

So it’s important to give it a good freshwater flush, maybe with salt-remover like Salt-X before you winterize it.

For this you can use “earmuffs” that clamp over the  engine’s raw-water intake ports, plus a garden hose to supply fresh water, plus an in-line mixing unit installed in the hose to draw in the anti-salt fluid.

As an alternative you can use a clean trash can filled with fresh water to a level above the engine’s intakes, including anti-salt fluid if you want. Note: Don’t try this on anything but a small, portable engine. You should be able to brace or tie off both the trash can and the engine. For me the method has worked on engines up to 15 horsepower and 90 pounds, but it’s easier with, say, an 8-horse, 75-pound engine (shown here) or smaller.

You’ll be running in neutral with the lower unit submerged, so you don’t need to remove the prop for safety — but it’s never a bad idea.

When you're ready to finish flushing, spray engine fogger directly into the carburetor. This will stop the engine and prevent corrosion over the winter.

When you’re ready to finish flushing, spray engine fogger directly into the carburetor. This will stop the engine and prevent corrosion over the winter.

Here are the steps I take to winterize:

  • Take the cowling off the engine, start it, and it warm all the way up, making sure it’s peeing a good stream of water back into the barrel. Leave it running in the fresh water for plenty of time – 20 to 30 minutes.
  • If you’ve mixed in salt remover, take the engine out of the barrel, empty the barrel, refill it with fresh water, put the engine back, run it, and rinse for another 5 minutes.
  • If you’re unable to get to the fuel-filter bowl (see below) disconnect the fuel hose from the engine now and let the engine run out of gas. Stand by with your can of engine fogger, and just as the engine starts to stutter, spray the fogger directly into the carburetor. The fogger will stop the engine and prevent corrosion over the winter.
  • If you can get to the fuel filter assembly, another method is just to spray the fogger into the carburetor when you’re ready to finish flushing.
  • Then disconnect the fuel hose.
  • Unscrew the fuel filter bowl, check the filter element inside, and empty the fuel from the bowl into your gas tank or some other suitable receptacle. Screw the bowl and clean filter element back onto the engine. They can stay dry for the winter.
  • Take the engine out of the water, give the lower unit a good scrub, rinse it one last time, dry it off, and clamp it to an engine dolly or workbench to finish the winterizing.

    Unscrew the fuel filter bowl from the engine, make sure the element is clean, empty the fuel into your gas tank, then screw the empty assembly back into the engine dry.

    Unscrew the fuel filter bowl from the engine (top), make sure the element is clean, empty the fuel into your gas tank (bottom), then screw the empty assembly back into the engine dry.

  • Remove the spark plugs and spray fogger into the cylinders until it begins to pour out. Wipe up, wipe the spark plugs clean, and reinstall them.
  • Wipe off all the old, salty grease and apply new grease to the bracket, swivel joint, throttle assembly, cowling latch – any place where grease is needed.
  • Check and replace the zinc(s) on the lower unit.
  • Leave the engine upright for the winter, either clamped to a dolly or bench, or leaning in a corner. Don’t lie it down flat.

If you’ve been thinking about replacing the oil in the lower unit, now is a good time to do it – better than leaving dirty oil to fester over the winter, especially if there’s a chance that it’s water-tainted. Here’s a good video from Boats.com on how to change lower-unit oil.

Finally, and very importantly, winterize your portable fuel tank. A half-full tank with ethanol-laced fuel left alone for the winter is likely to cause you big headaches in the spring. So, Option One is to completely empty your tank and burn the fuel in something else (it’s chainsaw and woodpile time where I live; I just add a bit of 2-cycle oil to get the mixture right for the saw), or, Option Two, fill that tank right to the top with fresh fuel and the additives of your choice. I use a mixture of storage additive and anti-ethanol stabilizer. Also disconnect the fuel hose from the tank, drain the fuel out, and pour that into the stabilized fuel, too.

Remove the spark plugs, fog the cylinders, wipe the plugs clean, and reinstall them.

Remove the spark plugs, fog the cylinders, wipe the plugs clean, and reinstall them.

If you have a diesel engine, a bigger outboard (earmuffs required), or a stern-drive, see the other winterizing tips below.

How to Winterize a Four-Stroke Outboard: Video
How to Winterize Your Stern Drive and Pressure Water System
Winterizing Your Diesel Engine: Oil Change
Winterizing Your Diesel Engine: Cooling System

 

 

Comments

  1. I’m guessing you take these same steps for say a 60HP outboard? This can go a long way into preserving our boats!

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