How To Change Water Pump On 40 H.p. Mariner Outboard

Maintaining your outboard motor is crucial for its longevity and performance. One essential component that requires regular attention is the water pump. A malfunctioning water pump can lead to overheating and severe engine damage. In this comprehensive guide, we will provide you with a detailed step-by-step process on how to change the water pump on a 40 HP Mariner outboard.

What You’ll Need

Before you begin, gather the necessary tools and materials:

• New water pump kit
• Socket wrench set
• Screwdriver
• Pliers
• Gasket sealant
• Rags
• Safety glasses

Safety Precautions

Always remember to prioritize safety when working on your outboard motor:

• Disconnect the battery before starting any work.
• Wear safety glasses to protect your eyes from debris.
• Allow the engine to cool down before touching any components.

Step 1: Remove the Lower Unit

• Place the outboard motor in neutral.
• Locate the drain plug at the bottom of the lower unit and remove it to drain the gear oil.
• Disconnect the shift linkage and electrical connections.
• Remove the bolts holding the lower unit to the powerhead.
• Carefully separate the lower unit from the powerhead.

Step 2: Remove the Water Pump Housing

• Identify the water pump housing located on the lower unit.
• Remove the bolts holding the housing in place.
• Gently pry the housing away from the lower unit.

Step 3: Remove the Old Water Pump

• Inside the housing, you will find the old water pump.
• Remove the bolts holding the water pump in place.
• Carefully lift out the old water pump.

Step 4: Inspect the Impeller

• Inspect the impeller inside the old water pump. If it is damaged or worn, replace it with a new one from the water pump kit.

Step 5: Install the New Water Pump

• Apply a thin layer of gasket sealant to the mating surfaces of the new water pump and the housing.
• Insert the new water pump into the housing.
• Secure the water pump with the bolts.

Step 6: Reinstall the Water Pump Housing

• Position the water pump housing back onto the lower unit.
• Secure the housing with the bolts.

Step 7: Reinstall the Lower Unit

• Align the lower unit with the powerhead.
• Insert the bolts and tighten them securely.
• Reconnect the shift linkage and electrical connections.
• Replace the drain plug and fill the lower unit with gear oil.

Troubleshooting

• If the water pump continues to fail after replacement, check for any obstructions in the water intake system.
• Inspect the impeller housing for cracks or damage.
• Ensure that the water pump belt is properly tensioned.

The Bottom Line

Replacing the water pump on a 40 HP Mariner outboard is a straightforward process that can be completed with the right tools and a bit of patience. By following these steps, you can ensure that your outboard motor receives the proper cooling it needs to operate efficiently and reliably.

Frequently Asked Questions

Q1: How often should I replace the water pump on my 40 HP Mariner outboard?

A1: It is recommended to replace the water pump every 2-3 years or as per the manufacturer’s maintenance schedule.

Q2: What are the signs of a failing water pump?

A2: Overheating, reduced water flow, and a noisy water pump are all indicators of a failing water pump.

Q3: Can I use any water pump kit for my 40 HP Mariner outboard?

A3: No, it is important to use a water pump kit specifically designed for your outboard model and year.