Winterizing Your Mercury 4-Cylinder: Step-By-Step Guide

Winterizing your Mercury 4-cylinder boat engine is essential to avoid engine damage and ensure a smooth start to the next boating season. While the process may seem daunting, it is relatively straightforward and can be done yourself or by an authorized dealer. Here are the basic steps to winterize your outboard engine:

- Treat the fuel system by adding a fuel stabilizer to fresh fuel and running the motor to circulate the stabilized fuel.

- Change the oil and filter, especially if it has been more than 100 hours or one season since the last change.

- Replace the gearcase lube and inspect for water contamination, which could lead to severe damage.

- Protect the engine internals by treating them with engine oil or fogging oil to prevent corrosion.

- Grease the prop shaft and other lubrication points.

- Check and touch up the paint on any exposed aluminum on the gearcase or skeg to prevent corrosion.

- Store the engine upright to allow for water drainage and prevent freezing damage.

- Disconnect and store your batteries properly.

Winterizing a Mercury 4-Cylinder Boat Engine

Treat the fuel system

To treat the fuel system of your Mercury 4-cylinder boat engine, you should always store your boat with fresh fuel that has been treated with a marine fuel stabilizer. Fuel that is left untreated will begin to oxidize and form a gum-like substance in the engine's fuel system. This is especially true for outboards equipped with carburetors.

If possible, try to run your boat's fuel tank almost empty at the end of the season, and then add fresh fuel before storage. If the fuel in your tank is more than a month old and it's too late in the season to use it up, have it pumped out and replace it with fresh fuel.

If you have an older boat with a vented fuel tank, it's advisable to fill the tank with fresh fuel to prevent condensation from forming. Stop filling when the tank is about 95% full, as extreme temperature changes over the winter can cause the fuel to expand, potentially forcing gas out of the vent. Newer tanks, on the other hand, don't need to be filled as they can't freely vent to the atmosphere and won't collect moisture from the air.

Once you've added fresh fuel, add the correct amount of fuel stabilizer to the fresh fuel. Treating the fuel with a stabilizer such as Mercury Quickstor will help to optimize the fuel, remove any leftover deposits from the engine, and protect the fuel system over the winter months.

It's important to circulate the treated fuel throughout the entire fuel system by running the boat for about 10 minutes, either in the water or while connected to a garden hose (following the owner's manual instructions). Finally, replace the fuel filter, and your motor's fuel system will be ready for the next season.

Change the oil and filter

Changing the oil and filter is an important step in winterizing your Mercury 4-cylinder boat engine. This process will help protect your engine during long-term storage and ensure that it's ready for the next boating season. Here's a detailed guide on how to change the oil and filter:

Step 1: Gather the Necessary Supplies

Before you begin, make sure you have all the required supplies. You will need a suitable oil change kit, such as the Mercury Oil Change Kit, which includes oil, an oil filter, and a drain plug seal. You can purchase this kit from an authorized Mercury dealer or marine service facility. Additionally, you'll need basic tools like a wrench or a screwdriver.

Step 2: Consult the Owner's Manual

Refer to the owner's manual of your Mercury 4-cylinder engine for specific instructions and maintenance products recommended by the manufacturer. The manual will provide essential information, such as the type of oil and filter to use, the location of the oil drain and filter, and the oil change procedure specific to your engine model.

Step 3: Prepare the Engine

Before draining the oil, it is recommended to start the engine and let it run for a brief period to circulate the old oil. This helps distribute the oil throughout the engine, making it easier to drain. However, make sure the engine is turned off before proceeding with the oil change.

Step 4: Drain the Old Oil

Position a drain pan or container underneath the engine to collect the used oil. Locate the oil drain plug, which is typically at the bottom of the engine. Using the appropriate tool, loosen and remove the drain plug, allowing the old oil to drain into the pan. Be careful not to strip the threads of the drain plug, as this can cause leakage.

Step 5: Replace the Oil Filter

After draining the oil, locate the oil filter. The oil filter is responsible for trapping contaminants and debris in the oil. It is usually located near the engine and can be identified by its cylindrical or canister-like shape. Remove the old oil filter using a filter wrench or oil filter pliers. Be sure to have a rag or towel handy to wipe up any spilled oil.

Step 6: Install the New Oil Filter

Before installing the new oil filter, make sure to clean the mounting surface where the old filter was seated. Check the new oil filter's rubber gasket for any defects or damage. Apply a thin coat of fresh oil to the gasket before installing the new filter. Hand-tighten the new oil filter, ensuring it is secure and aligned correctly. Do not overtighten, as this can damage the filter and the engine.

Step 7: Refill with New Oil

Once the new oil filter is in place, you can start refilling the engine with fresh oil. Locate the oil filler cap, typically on the top of the engine, and remove it. Use a funnel to pour in the recommended type and amount of oil specified in your owner's manual. Be careful not to overfill the engine.

Step 8: Reinstall the Drain Plug

After draining the old oil, wipe the drain plug and the surrounding area to remove any residual oil. Reinstall the drain plug by hand-tightening it first and then tightening it further with a wrench. Ensure that the drain plug is secure and properly sealed to prevent oil leakage.

Step 9: Start the Engine and Check for Leaks

After changing the oil and filter, it is important to start the engine briefly to circulate the new oil. Let the engine run for a few minutes, then check for any signs of oil leaks around the drain plug and oil filter. If you notice any leaks, tighten the drain plug and filter, and wipe off any excess oil.

Step 10: Dispose of Used Oil Properly

Used engine oil should be disposed of responsibly and in accordance with local regulations. Contact your local waste management authority or recycling center to find out how and where to dispose of used oil. Do not pour used oil down the drain or into storm sewers, as it can contaminate water bodies and harm the environment.

Remember, changing the oil and filter is a crucial step in winterizing your Mercury 4-cylinder boat engine. It helps protect the engine from corrosion and ensures that your boat will be ready for the next boating season. Always follow the manufacturer's recommendations and consult a professional marine technician if you have any questions or concerns.

Protect the engine internals

Protecting the engine internals of your Mercury 4-cylinder boat engine is a crucial step in winterization to prevent corrosion. Here are the detailed steps you should follow:

Step 1: Remove the Spark Plugs

Before treating the engine internals, it is essential to remove the spark plugs. This step provides access to the cylinders and ensures that the treatment is applied directly to the internal components.

Step 2: Apply Engine Oil or Fogging Oil

For long-term storage, it is recommended to use either engine oil or fogging oil to protect the internal engine components. Fogging oil is a wax-based oil specifically designed to prevent corrosion. You should inject approximately one ounce of engine oil or spray fogging oil directly into each cylinder. Follow the directions on the product's container to ensure proper application.

Step 3: Distribute the Oil Evenly

After applying the oil, it is important to distribute it evenly across all internal components. To achieve this, you can manually rotate the engine flywheel a few revolutions. This action ensures that the oil coats all surfaces and provides maximum protection.

Step 4: Reinstall the Spark Plugs

Once you have evenly distributed the oil, the final step is to reinstall the spark plugs. This step ensures that the engine is ready for operation when the boating season arrives.

Additional Tips:

It is worth noting that some sources recommend using a marine-specific fogging oil product, such as Quicksilver Storage Seal. Additionally, it is crucial to perform this procedure after changing the engine oil and filter, as old oil can expose internal components to moisture and acidic combustion byproducts, leading to corrosion.

Grease the prop shaft and other points

To winterize a Mercury 4-cylinder boat engine, one of the steps is to grease the prop shaft and other points. This is an important step to ensure the engine is protected during the winter storage period.

Firstly, if you have removed the propeller to change the gear lube, it is a good time to check the hub kit and inspect the seal for any fishing line that may be present. This is often coated in grease and can be hard to spot, so use a sharp pick or small screwdriver to remove any line. Next, grease the prop shaft with a quality marine grease, such as Quicksilver 2-4-C. It is also recommended to grease other main lubrication points, including the steering linkage and tilt/trim mechanism, with a grease gun.

By following these steps and greasing the prop shaft and other points, you can help ensure your Mercury 4-cylinder boat engine is properly winterized and protected during the off-season.

Check and store the battery

To check and store the battery of a Mercury 4-cylinder boat engine, follow these steps:

Firstly, if your battery is a lead-acid battery, you must inspect the fluid level and add distilled water if necessary. It is important to ensure that the battery is fully charged.

Next, disconnect the battery from the boat and store it in a cool, dry place. It is recommended to store the battery on a maintenance charger to keep it charged and fresh until the spring. This will ensure that your battery is ready to go when you reinstall it in the spring.

Additionally, it is important to note that some dealers recommend using a battery terminal cleaner and protector to spray a corrosion inhibitor on the battery terminals before winter storage. This will help prevent corrosion and maintain the battery's performance.

Frequently asked questions