It’s not difficult winterizing outboard motors, and small models can be done in an afternoon. 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 some of us who leave our boats floating the whole time in a spot with no freshwater supply, that means never.) In this case 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 or barrel 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 eight-horse, 75-pound engine (shown here) or smaller.
You’ll be running in neutral with the lower unit submerged – never shift into gear – so you don’t need to remove the prop for safety. Still, it’s never a bad idea.
Winterizing a Small Outboard with a Carburetor
Here are the steps I take to winterize a small carbureted outboard:
- Take the cowling off the engine, start it, and warm it to operating temperature, making sure it’s the tell-tale is releasing a good stream of water back into the barrel. Leave it running in the fresh water for five to 10 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 five 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.
- 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.
- 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.
Winterizing a Small Outboard with EFI
If the engine is fuel injected, which is common with many of the newer small outboards, obviously you can skip all the steps related to a carburetor. Instead, mix the manufacturer’s recommended fogging fluid with fuel in a remote tank and simply run it through the outboard until visible smoke is coming from the exhaust.
Steps for Winterizing all Small Outboard Engines
After these steps have been completed, now is the time to perform oil changes for both the lower unit, and, in the case of four-strokes, the powerhead oil. You don’t want to leave 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.
You’ll also want to:
- 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 if necessary, 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.
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 two-cycle oil to get the mixture right for the saw), or, Option Two, fill that tank right to the top with fresh fuel and put in the stabilization additives of your choice. I use a mixture of storage additive and anti-ethanol stabilizer; note that with ethanol and boat fuel it’s absolutely critical to add that stabilizer. Also disconnect the fuel hose from the tank, drain the fuel out, and pour that into the stabilized fuel, too.
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 Boat
- How to Winterize a Four-Stroke Outboard: Video
- Winterizing Your Diesel Engine: Oil Change
- Winterizing Your Diesel Engine: Cooling System
Next spring be sure to check out: Get your Boat Ready for Spring: Spring Commissioning Checklist.
Editor’s note: This article originally appeared on Boat Trader in October 2013 and was last updated in October of 2023.
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