How to Winterize a Boat Engine

How to Winterize a Boat Engine
When winter winds start to blow, it's time to pack away the boat. When you prepare to store your boat for the winter, you must go through a winterizing process to help it withstand low temperatures. If you don't prepare your engine properly, you can shorten its lifespan. How you winterize your boat depends on whether you have an inboard or outboard motor.

Instructions

Difficulty: Moderate

Outboard motors

Things You’ll Need:
  • Wrench Screwdriver Water hose Fogging oil Anti-corrosion spray Grease
  • Wrench
  • Screwdriver
  • Water hose
  • Fogging oil
  • Anti-corrosion spray
  • Grease
Step 1
Remove the silencer cover on your engine and connect a hose to your water intake.
Step 2
Turn on engine at a high RPM, keeping it locked in idle. Increase the RPM slightly and disconnect the fuel line where it connects to the engine. Spray 1-2 ounces of fogging oil into each carburetor as the motor runs out of fuel and dies.
Step 3
Remove all spark plugs and spray fogging oil in each cylinder. Hand turn the flywheel a few rotations.
Step 4
Change out the lower-unit lube, removing the prop and greasing the shaft, fittings and lube points. Spray corrosion-preventative fluid onto the engine.

Inboard motors

Step 1
Disconnect and remove the battery. Change the engine coolant if your motor uses freshwater to cool itself.
Step 2
Run the engine until it heats up, then change your engine and transmission oil. Replace the engine oil filter.
Step 3
Top off the fuel tank if you have a diesel engine, or run the engine until it runs out of fuel if it uses gasoline. When your gasoline engine is running, replace the flame arrestor and spray fogging oil into the air intake. You will also have to drain the fuel tank and supply lines on a gasoline engine.
Step 4
Disconnect the outlet hose on the raw-water pump and disconnect water-discharge hose where it meets the exhaust manifold or riser. Run fresh water through the discharge hose.
Step 5
Reconnect the water-pump outlet hose on a diesel engine use a funnel to pour a mix of half-propylene glycol antifreeze and water into the funnel. Let the mixture sit in the engine block for several minutes, then unplug all water-drain plugs to let the engine drain.
Step 6
Remove the raw-water impeller and rinse with fresh water.
Step 7
Remove the spark plugs on gasoline engines and spray fogging oil into the holes. Replace spark plugs.
Step 8
Spray fogging oil into the air intake of a diesel engine and slowly crank the engine with your hand to spread the oil throughout the interior.
Step 9
Drain the muffler canister, then degrease and derust all painted surfaces to protect against corrosion.
Step 10
Remove control cables from their housings and grease them, then do the same for any linkages or pivots. Coat all painted engine surfaces in an anti-corrosion spray.
Step 11
Tighten the stuffing box, if you will be storing it in water during the winter.

Tips & Warnings

 
Charge the battery every month or two during the winter. Make sure the engine is stored vertically so the water can drain. If stored on the side, water will become trapped and freeze.
 
Charge the battery every month or two during the winter.
 
Make sure the engine is stored vertically so the water can drain. If stored on the side, water will become trapped and freeze.

Article Written By Jonathan Croswell

Jonathan Croswell has spent more than five years writing and editing for a number of newspapers and online publications, including the "Omaha World-Herald" and "New York Newsday." Croswell received a Bachelor of Arts degree in English from the University of Nebraska and is currently pursuing a Master's of Health and Exercise Science at Portland State University.

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