Unveiling the Secrets: How to Replace Your Yamaha 90 HP Outboard Water Pump with Ease

Replacing the water pump on your Yamaha 90 HP outboard motor is a crucial maintenance task that ensures the engine’s cooling system functions optimally. This comprehensive guide will provide you with step-by-step instructions, tools required, and troubleshooting tips to help you successfully complete the replacement.

Tools and Materials Required:

• New water pump kit
• Socket wrench set
• Screwdriver set
• Pliers
• Rags
• Gasket sealant
• Marine grease

Step-by-Step Instructions:

1. Safety Precautions:

• Disconnect the battery to prevent electrical shock.
• Allow the engine to cool down completely.

2. Remove the Lower Unit:

• Place the engine in neutral and tilt it up.
• Remove the bolts securing the lower unit to the powerhead.
• Carefully detach the lower unit and drain any remaining water.

3. Locate the Water Pump:

• The water pump is typically located on the lower unit’s front or side.

4. Remove the Old Water Pump:

• Remove the bolts or screws holding the water pump in place.
• Carefully pull the old water pump out of its housing.

5. Clean the Housing:

• Remove any debris or old gasket material from the water pump housing.
• Use a rag to clean the surfaces where the new water pump will be installed.

6. Install the New Water Pump:

• Apply a thin layer of marine grease to the new water pump impeller.
• Insert the new water pump into the housing and align it correctly.
• Secure the water pump with the bolts or screws.

7. Reassemble the Lower Unit:

• Align the lower unit with the powerhead and lift it into place.
• Tighten the bolts securing the lower unit.
• Reconnect the gear shift linkage.

8. Test the Water Pump:

• Reconnect the battery.
• Start the engine and run it at idle.
• Check for any leaks around the water pump.
• Observe the water stream from the telltale indicator to ensure proper water flow.

Troubleshooting Tips:

• If the water pump is not circulating water, check for blockages in the intake hose or impeller damage.
• If the water pump is leaking, tighten the bolts or replace the gasket.
• If the impeller is worn or damaged, replace it with a new one.
• If the telltale indicator is not producing a steady stream of water, check the water pump, thermostat, or cooling system for problems.

Wrap-Up:

Replacing the water pump on a Yamaha 90 HP outboard motor is a relatively straightforward task that can be completed with basic mechanical skills and the right tools. By following these instructions and troubleshooting tips, you can ensure your outboard engine receives proper cooling and operates reliably for many years to come.

Questions We Hear a Lot

Q: How often should I replace the water pump on my Yamaha 90 HP outboard motor?
A: Yamaha recommends replacing the water pump every 100 hours of operation or annually, whichever comes first.

Q: Can I use an aftermarket water pump kit?
A: Yes, you can use an aftermarket water pump kit, but ensure it is compatible with your Yamaha 90 HP outboard motor model.

Q: What are the signs of a failing water pump?
A: Signs of a failing water pump include reduced water flow from the telltale indicator, overheating, or engine damage due to insufficient cooling.