Step-by-Step Guide: Replace Your Yamaha 115 Four Stroke Water Pump in Minutes

Maintaining the health and performance of your Yamaha 115 four-stroke outboard motor is crucial for a reliable and enjoyable boating experience. One essential maintenance task is replacing the water pump, which plays a vital role in cooling the engine. This guide will provide a step-by-step tutorial on how to change the water pump on your Yamaha 115 four stroke, ensuring optimal engine performance and longevity.

Tools and Materials Required

Before you begin, gather the necessary tools and materials:

• Yamaha 115 four-stroke outboard motor
• New Yamaha water pump kit
• 10mm socket wrench
• 12mm socket wrench
• Phillips head screwdriver
• Flat head screwdriver
• Sealant
• Rags or paper towels
• Bucket or container

Safety Precautions

• Disconnect the battery before starting any work.
• Allow the engine to cool down completely before touching any components.
• Wear appropriate safety gear, including gloves and safety glasses.

Step-by-Step Guide

1. Remove the Lower Unit

• Locate the two bolts securing the lower unit to the powerhead.
• Use a 10mm socket wrench to loosen and remove the bolts.
• Carefully lift the lower unit straight up and away from the powerhead.

2. Access the Water Pump

• Once the lower unit is removed, you’ll see the water pump housing located at the bottom of the powerhead.
• Use a Phillips head screwdriver to remove the screws holding the water pump housing in place.

3. Remove the Old Water Pump

• Carefully remove the water pump housing to expose the impeller and seal.
• Use a flat head screwdriver to gently pry out the impeller.
• Inspect the impeller for damage or wear and replace if necessary.

4. Install the New Water Pump

• Apply a thin layer of sealant to the new impeller and insert it into the water pump housing.
• Place the new seal over the impeller and press it into the housing.
• Reinstall the water pump housing and secure it with the screws.

5. Reinstall the Lower Unit

• Carefully lift the lower unit and align it with the powerhead.
• Lower the lower unit and insert the bolts.
• Hand-tighten the bolts and then use a 12mm socket wrench to fully tighten them.

6. Connect the Water Line

• Reconnect the water line from the lower unit to the water pump housing.
• Ensure a secure connection to prevent water leakage.

7. Test the Water Pump

• Reconnect the battery.
• Start the engine and allow it to idle.
• Check for any water leaking from the water pump housing or connections.
• If there are no leaks, the water pump is installed correctly.

Additional Tips

• Replace the water pump impeller every 1-2 years to maintain optimal cooling performance.
• Inspect the water pump housing for any cracks or damage and replace if necessary.
• Use genuine Yamaha parts for the best fit and performance.

Wrapping Up

Changing the water pump on your Yamaha 115 four-stroke outboard motor is a relatively straightforward task that can be completed in about an hour. By following these steps carefully, you can ensure that your engine runs smoothly and efficiently for many years to come.

What People Want to Know

Q: How often should I change the water pump on my Yamaha 115 four-stroke outboard motor?
A: It is recommended to replace the water pump impeller every 1-2 years for optimal cooling performance.

Q: What are the signs of a failing water pump?
A: Overheating engine, reduced water pressure, or visible water leaks from the water pump housing.

Q: Can I use aftermarket parts for the water pump?
A: While aftermarket parts may be available, it is always recommended to use genuine Yamaha parts for the best fit and performance.