Winterize Mercury 115 Pro Xs

Winterize Mercury 115 Pro Xs

by

As the boating season comes to an end, properly winterizing your Mercury 115 Pro XS is essential to keep it in top condition for the next season. Winterization prevents engine damage, corrosion, and fuel system issues caused by cold temperatures and long periods of inactivity.

This guide provides a detailed step-by-step process to winterize your Mercury 115 Pro XS efficiently, ensuring smooth performance when you’re ready to hit the water again.

Why Winterization is Important

1. Prevents Engine Damage

  • Freezing temperatures can cause cracked engine components.

  • Protects the cooling system from ice expansion.

2. Avoids Fuel System Issues

  • Stale fuel can lead to clogged injectors and carburetor problems.

  • Ethanol in fuel absorbs moisture, causing phase separation.

3. Extends Engine Life

  • Prevents internal corrosion.

  • Ensures a quick and hassle-free start in spring.

Tools and Supplies Needed

Before starting the winterization process, gather these essential supplies:

  • Marine fuel stabilizer

  • Fogging oil

  • Engine flush kit

  • Freshwater supply

  • SAE 90 lower unit gear oil

  • Drain pan

  • New fuel filter and oil filter

  • Spark plug wrench

  • Grease gun with marine grease

  • Clean rags and safety gloves

Step-by-Step Guide to Winterizing Mercury 115 Pro XS

1. Add Fuel Stabilizer

Fuel stabilizer helps prevent ethanol-related issues and fuel degradation.

Steps:

  1. Fill the fuel tank at least ¾ full to minimize condensation.

  2. Add the recommended amount of fuel stabilizer (check the manufacturer’s instructions).

  3. Run the engine for 5-10 minutes to circulate stabilized fuel through the system.

2. Flush the Cooling System

Flushing removes salt, debris, and contaminants from the cooling passages.

Steps:

  1. Connect a flush kit or garden hose to the engine’s flushing port.

  2. Start the engine and let it idle for 10 minutes.

  3. Ensure a steady water flow through the telltale.

  4. Turn off the engine and disconnect the hose.

3. Fog the Engine

Fogging oil protects internal engine components from corrosion during storage.

Steps:

  1. Remove the air intake cover to access the throttle body.

  2. Spray fogging oil into the air intake while the engine runs at low RPM.

  3. Turn off the engine once you see white smoke from the exhaust.

4. Change Engine Oil and Filter

Old oil contains contaminants that can cause corrosion.

Steps:

  1. Warm up the engine for 5 minutes to thin the oil.

  2. Remove the oil drain plug and let the oil drain completely.

  3. Replace with fresh marine-grade 4-stroke oil.

  4. Install a new oil filter and tighten it securely.

5. Drain and Refill Lower Unit Gear Oil

Water in the lower unit can freeze and cause gear case damage.

Steps:

  1. Place a drain pan under the lower unit.

  2. Remove the lower drain screw and allow the oil to drain.

  3. Check for milky oil, which indicates water contamination (repair seals if necessary).

  4. Refill with fresh SAE 90 marine gear oil using a gear pump.

  5. Reinstall the drain screw securely.

6. Inspect and Replace the Fuel Filter

A clogged fuel filter can cause engine performance issues.

Steps:

  1. Locate the fuel filter under the cowling.

  2. Remove the old filter and inspect for debris or water.

  3. Install a new fuel filter and tighten it properly.

7. Check and Replace Spark Plugs

Worn-out spark plugs can lead to hard starts and misfiring.

Steps:

  1. Use a spark plug wrench to remove old plugs.

  2. Inspect for carbon buildup or corrosion.

  3. Install new spark plugs and tighten to specifications.

8. Lubricate Moving Parts

Proper lubrication prevents rust and stiffness during storage.

Steps:

  1. Apply marine grease to the steering linkage, throttle cables, and pivot points.

  2. Grease the propeller shaft to prevent corrosion.

9. Remove the Battery

Cold temperatures can drain and damage the battery.

Steps:

  1. Disconnect the negative (-) terminal first, then the positive (+) terminal.

  2. Store the battery in a cool, dry place.

  3. Connect a trickle charger to maintain charge.

10. Store the Engine Properly

Protecting your Mercury 115 Pro XS from harsh winter conditions is crucial.

Steps:

  1. Store the boat in a dry, well-ventilated space.

  2. Use an engine cover to prevent dust buildup.

  3. Tilt the engine downward to drain any remaining water.

Common Winterization Mistakes to Avoid

1. Forgetting to Use Fuel Stabilizer

  • Old fuel can gum up the carburetor and fuel injectors.

2. Not Draining the Lower Unit

  • Water in the gear case can freeze and crack components.

3. Ignoring the Battery

  • A dead battery in spring can cause delays and added costs.

4. Skipping Fogging Oil

  • Internal corrosion can lead to engine failure.

FAQs About Winterizing Mercury 115 Pro XS

1. How Often Should I Winterize My Mercury 115 Pro XS?

  • Winterize the engine before every off-season or if the boat will sit unused for more than a month.

2. Can I Skip Oil Changes If My Engine Is New?

  • No. Even new engines need fresh oil before winter storage to prevent internal damage.

3. Should I Remove the Propeller?

  • It’s recommended. Removing the propeller allows you to inspect the shaft for fishing lines or debris.

4. Can I Use Car Engine Oil Instead of Marine Oil?

  • No. Marine-grade oil is specially formulated to handle high moisture and salt exposure.

5. Do I Need a Professional for Winterization?

  • Many boaters prefer DIY winterization, but professional services can ensure thorough protection.

Properly winterizing your Mercury 115 Pro XS ensures that your engine remains in optimal condition throughout the off-season. By following these steps, you can prevent costly repairs, extend your engine’s lifespan, and enjoy a trouble-free start when boating season returns.

Taking the time to flush, lubricate, and store your engine correctly will save you money and effort in the long run.