Winterize Your Boat

by David Randall

        When the temperature starts falling close to freezing and water is left inside your engine or gear case, the results could be a cracked block or housing and a repair bill in the spring that runs from hundreds to thousands of dollars. It is easy enough to prevent this unhappy circumstance by putting our boat’s engine to bed properly at the end of the boating season. Oxidation and rust never stops, but freezing kills. Allowing corrosion to flourish during the off-season is less dramatic but equally destructive. Corrosion can establish a foothold on idle components, so liberal use of corrosion inhibitors, both internal and external, is a second guiding principle for winterizing.
Many fishermen use their outboard powered boat year round, so I will concentrate on the I/O and inboard boat winterizing procedures that we follow here at Randall Marine in Phenix City, AL.
If your owner’s manual includes winterizing instructions, then that is the procedure you should follow. In the absence of manufacturer’s instructions, I will list the engine winterizing procedure we use at Randall Marine for I/O and inboard boats. Some steps on our list may not apply to your particular engine. The only items you should need to complete the task yourself, other than your engine’s normal lubricants are: an aerosol can of fogging oil, a fuel stabilizer and for inboards and I/O’s, a gallon or two of non-toxic propylene glycol antifreeze.
If your engine has a closed water cooling system, drain and replace the coolant.  Most coolant loses its anti-corrosion properties over time, so replacing it every year with a fresh 50-50 mix protects the inside of your engine.
Check your engine oil and filter, and change if necessary. Add a good fuel stabilizer and fill your fuel cell to 90% to prevent internal condensation in the tank.
Check your fuel filter, replace if necessary and check for fuel leaks. Crank the motor and allow it to warm up and distribute the stabilized fuel thru the fuel system. While the engine is running, remove the flame arrestor and spray fogging oil into the air intake. Give it an extra heavy shot just as the engine starves and dies. DO NOT spray fogging oil into any fuel injected motor.
Extend the control cables from their housings and coat them with grease. If you cannot remove them, tape an oil-filled bag tightly around the high end of the housing; the oil will work its way down the cable. Lubricate linkages and pivots.
Spray any unpainted parts of the motor with anti-corrosion protectant.
If your boat has a stern drive you will need to follow the above list for protecting the engine, but add to that several items from the outboard list for protecting the lower end. An additional requirement is filling the drive shaft housing with the appropriate lubricant. Remember that a stern drive needs to be in the full-down position for draining the water passages and for checking or adding gear lube. Store it in the down position.
If you are going to store your outboard engine, follow these simple guidelines.
Use a flushing attachment or run the outboard in a tank filled with clean water. While the engine is still running, disconnect the fuel line from the engine. When the engine dies, the fuel delivery components will be empty, preventing gums from forming in the stagnant gasoline and clogging lines and jets or injectors.
Before the engine runs out of fuel, spray fogging oil into the carburetor(s). Fogging oil is an anti-corrosive that will protect the internal surfaces of the carburetor and the cylinders. Typically the engine will run rough just before it runs out of fuel. As that happens, give the carburetor(s) a heavier shot of fogging oil to make sure internal surfaces are fully coated.

Disconnect the flush attachment or remove the motor from the flush tank. With the motor upright, let all water drain out of the pick-up. Open drain plugs (if any, see your owner’s manual) to empty the powerhead and intermediate housing. Rotate the flywheel of the motor a couple of times by hand or “bump” it with the starter to empty the water pump. If the motor will be exposed to freezing conditions, it is essential that no water remains inside.
Remove the spark plugs and spray fogging oil into the holes to coat the interior surfaces of the cylinders. Rotate the flywheel a few turns to spread the oil on the cylinder walls. While the plugs are out is the time to check them and re-gap or replace as required. Reinstall the spark plugs.
Clean all pivots and visible gears and protect them for the winter with oil or grease, as specified in your owner’s manual.
Use lubricant specified in your owner’s manual. Fill oil tank. This will prevent condensation from forming inside the tank.
Clean and lubricate your propeller shaft, and have the propeller serviced if it has signs of damage or impact.

Drain your fuel tank and fuel supply lines. If emptying the tank completely is not practical for your boat, then top it off to 95% full. Gasoline with ethanol is subject to phase separation if water gets into the fuel, which it will surely do with a half-empty tank over the winter. Filling the tank limits the air space inside the tank and reduces the potential for internal condensation. If you cannot drain your tank, STABILIZE the fuel. If you leave your tank full, dose it with an appropriate amount of gasoline stabilizer to combat the formation of passage-clogging gums.

This may seem like a lot of preventive work, but your spring boating pleasure will be better assured if you have taken the time to protect your boat, your motor and your trailer from possible winter damage.  Be sure to call Randall Marine, 334-298-1313, if you have any questions about this article or need to schedule your boat for service in our service department.