Table of Contents
- Introduction
- Tools & Materials Checklist
- Step-by-Step Guide for Gasoline Outboards
- Common Mistakes to Avoid
- Frequently Asked Questions on How To Winterize An Outboard Motor
As the days get shorter and the temperatures begin to drop, it’s a clear sign that the boating season is coming to an end. This is a crucial time for boat owners, because properly preparing your engine for storage is the best way to ensure it will be ready to go when spring returns. Knowing how to winterize an outboard motor is a vital skill that can save you from costly repairs and headaches down the line. This guide will walk you through the essential steps to prepare your motor for the off-season. The process of winterizing an outboard engine is a simple form of preventative maintenance that protects your investment.
Tools & Materials Checklist
- Fuel stabilizer: Use a marine-specific formula.
- Outboard flushing attachments (earmuffs): These connect to your lower unit’s water intakes.
- Freshwater hose: For flushing out the engine's cooling system.
- Lower unit gear lube and a pump: Essential for lubricating the lower unit.
- For 4-strokes: Fresh engine oil and a new oil filter.
- Fogging oil: Crucial for internal engine protection.
- Marine grease and a grease gun: For lubricating moving parts.
- New spark plugs and a spark plug wrench: An important final step.
- Battery terminal cleaner and protectant: To prevent corrosion on your battery.
- Battery maintainer or charger: For proper long-term battery storage.
Step-by-Step Guide for Gasoline Outboards
Follow these steps to properly winterize the outboard.
- Stabilize the Fuel: This is the most critical step in the entire process. Untreated gasoline can break down over a few months, forming gums and varnish that will clog your fuel lines, injectors, and carburetors. Add the recommended amount of a quality fuel stabilizer directly to your fuel tank. Then, run the engine for about 10-15 minutes to ensure the treated fuel circulates throughout the entire fuel system. This ensures every component is protected from fuel degradation, which is key to how to winterize an outboard boat motor.
- Flush the Cooling System: To remove salt, silt, and other debris that can cause corrosion, you need to flush the engine's cooling system. Attach the flushing earmuffs to the water intakes on the lower unit, connect your freshwater hose, and turn on the water. Start the engine and let it run for a solid 10 minutes. This flushes out the entire system, a critical part of winterizing an outboard boat motor to prevent internal damage.
- Change the Lower Unit Gear Lube: Old gear lube can be contaminated with water. Water can freeze and expand, cracking the lower unit housing. To avoid this, place a pan under the motor and remove both the vent and drain screws on the lower unit. Let the old fluid drain completely. Using a pump, pump in new gear lube from the bottom drain hole until it starts to come out of the top vent hole. Replace the vent screw, then remove the pump and quickly replace the drain screw.
- Change the Engine Oil (for 4-Strokes Only) and Oil Filter: This is a defining task for how to winterize a four-stroke outboard. Old engine oil contains corrosive acids and contaminants from engine operation. Leaving these in the engine over the winter can cause pitting and damage to internal components. Drain the old oil, replace the oil filter, and fill with the manufacturer’s recommended marine-grade oil. This is an essential part of winterizing an outboard boat motor for four-stroke engines.
- Lubricate and Protect: Your outboard has many moving parts that need to be greased to prevent corrosion. Use a marine-grade grease gun to lubricate all the grease fittings on the motor, particularly on the steering and throttle linkages. Next, apply a liberal amount of a rust inhibitor spray to all exposed metal parts and the engine’s powerhead to create a protective barrier against moisture.
- Fog the Engine: Fogging is one of the most important steps to winterize an outboard. It involves spraying protective oil into the engine’s cylinders. This oil coats the cylinder walls and piston rings, preventing them from rusting and seizing during the months of inactivity.
- Service the Battery: Remove the battery from the boat. Clean the terminals and cable ends with a wire brush and apply a terminal protectant spray. Store the battery in a cool, dry place and use a marine-grade battery maintainer to keep it charged.
Common Mistakes to Avoid
When you winterize an outboard motor, it's easy to overlook a detail that can cause big problems later. Here are some of the most common mistakes to watch out for:
- Forgetting to Stabilize Fuel: This is the number one cause of no-start issues in the spring.
- Not Draining the Gear Lube Properly: If you don't drain all the fluid, any residual water can freeze and cause significant damage.
- Leaving the Battery in the Boat: Leaving the battery connected can lead to a slow discharge and a dead battery by spring.
Don't forget to inspect and replace your anode while you are performing these steps. The anode is a sacrificial piece of metal that protects your engine from corrosion. It’s an easy and inexpensive replacement that will save you money in the long run. Inspecting and replacing your anodes is an excellent bonus step when you winterize your outboard.
This guide has your motor covered, but for a complete checklist to protect your entire vessel, see our comprehensive boat winterization guide.
By following these steps, you’ve done a thorough job of winterizing the outboard. Taking the time now to complete these tasks will give you peace of mind and save you from the stress of a failed engine in the spring. For all the tools and products you need to get the job done right, stop by Fawcett Boat Supplies today!