DIY Guide: Changing the Impeller on Your Yamaha Outboard

Embarking on changing the impeller on your Yamaha outboard motor is a crucial maintenance step that ensures the longevity and efficiency of your engine. This DIY guide is designed to walk you through the process step by step, ensuring you can confidently perform this essential task. The impeller, a vital component of the engine's cooling system, requires regular inspection and replacement to prevent overheating and engine damage.

Whether you're a dedicated enthusiast or simply looking to expand your maintenance skills, this guide will provide the knowledge and techniques needed to successfully change the impeller on your Yamaha outboard.

In the video embedded within this article, the impeller replacement was performed on a Yamaha F200 outboard. However, the video and the step-by-step instructions included within this article apply to:

• F150
• F175
• F200

What You’ll Need for the Job

• Yamaha Water Pump Repair Kit
• Yamalube Marine Grease
• Screwdrivers
• Power Screwdriver
• Socket Wrench Set
• Mallet
• Chisel Set
• Rags 

Why is the Water Pump Important to Your Yamaha Outboard?

The water pump is vital to your Yamaha outboard's cooling system. Here’s why it's crucial:

• Prevents Overheating: The water pump circulates water through the engine, dissipating heat and preventing the engine from overheating.
• Ensures Engine Efficiency: Efficient cooling contributes to optimal engine performance, ensuring your outboard runs smoothly and efficiently.
• Extends Engine Life: By preventing overheating, the water pump helps avoid engine damage, extending the lifespan of your outboard motor.
• Maintains Fuel Economy: An engine that operates at the correct temperature is more fuel-efficient, saving you money and reducing emissions.
• Critical for Safe Boating: A failure in the cooling system can lead to engine breakdowns, potentially leaving you stranded. Regular maintenance of the water pump is essential for safe boating experiences.

In summary, the water pump is not just another component; it's central to the health and performance of your Yamaha outboard. Regular checks and maintenance are crucial to ensuring its reliability and safety on the water.

Signs of Potential Problems with the Impeller or Water Pump

To identify issues with your Yamaha outboard's impeller or water pump based on motor performance and other operational indicators, watch for these signs:

• Engine Overheating: A primary sign of a failing impeller or water pump is the engine running hotter than usual, which can potentially lead to overheating warnings.
• Decreased Water Flow from the Cooling System: If you notice a reduced flow of water exiting the cooling system, it could indicate a blockage or damage to the impeller.
• Unusual Noise from the Water Pump Area: Any new or unusual noises coming from the area of the water pump could signal a malfunction or debris caught in the impeller.
• Steam or Excessive Heat from the Engine While Running: Steam or noticeable heat emanating from the engine while in operation can be a symptom of inadequate cooling.
• Engine Performance Issues: Difficulty starting the engine, loss of power, or erratic performance might be linked to an inefficient cooling system caused by impeller or water pump problems.
• Visual Signs of Wear or Damage When Inspecting: Beyond performance, visual inspection can reveal damaged, worn, or broken impeller blades upon removal.

Tools and Materials Needed for Impeller Replacement

Having the right tools and materials to replace the impeller on your Yamaha outboard is crucial for a smooth and successful process. Here's what you'll need:

• New Water Pump Kit: Must match your Yamaha Outboard model.
• Marine Grease: Lubricates impeller and pump housing.
• Socket Wrench Set & Flathead Screwdrivers: For loosening/tightening tasks.
• Power Driver: Speeds up screw and bolt driving.
• Mallett: For tapping parts into place and removing/installing parts.
• Rags and paper towels: For cleaning and wiping tasks.
• Safety Glasses & Gloves: Protect eyes from debris and hands from cuts/abrasions.

Step-by-Step Guide to Removing the Old Impeller

1. Remove the Lower Unit (Gear Case)

• Position the lower unit in an appropriate workspace for convenient access during the procedure.

2. Remove Existing Water Pump Assembly

• Unfasten the bolts that hold the housing in place.
• Carefully remove the housing, trying to keep the cup stationary.
• Check the housing for wear or heat damage signs and replace them if needed.
• Remove the collar and spacer above the cup housing using a flathead screwdriver.
• Pull the metal impeller housing away from the shaft.
• Remove the washers securing the impeller to the plate, remembering the order of the two flat washers around the wave washer.
• Slide the impeller off the shaft by sliding it upwards.
• Inspect the impeller for any evidence of overheating, like melting.

3. Installing the New Water Pump Kit

• Slide the new impeller onto the shaft.
• Install the flat washer/wave washer sandwich.
• Slide the collar back into place on top of the wave/washers.
• Tap the collar and washers back into place using a mallet and wrench.
• Apply 2-4-C grease inside the plastic housing before inserting the O-ring.
• Install the O-ring and then the new metal cup into the plastic housing.
• Add more grease to the housing before installing the large O-ring.
• Slide the plastic housing back over the shaft.
• Hold the shaft with a cloth or paper towel and turn it clockwise while pressing down to ensure the housing is seated correctly.
• Reinstall the bolts securing the housing.

4. Reinstall the lower unit

 

Final Insights: Ensuring Your Outboard's Longevity Through Impeller Care

Replacing the impeller on your Yamaha outboard is a key maintenance task that can significantly impact the performance and longevity of your engine. By following the steps outlined in this guide, even those with minimal experience in boat maintenance can complete this task. Having the right tools and materials on hand, recognizing the signs of wear and damage, and understanding the importance of the water pump and impeller in your engine's cooling system are all critical components of this process.

Regular maintenance, including impeller replacement, ensures your outboard motor runs efficiently and reliably, helping you avoid costly repairs and extend the life of your engine. Remember, properly caring for your Yamaha outboard will ensure it remains ready for your next boating adventure.

**Important Note**

Always consult your engine's owner's manual for instructions and information specific to your engine. For clarification on changing a water pump impeller, consult a Yamaha-certified mechanic.

PartsVu and Platinum Mobile Marine Partnership

Huge thanks go to Frank Cutri, the owner and operator of Platinum Mobile Marine, a mobile mechanic service serving the Lee County, Florida area, for partnering with PartsVu on the Boat Maintenance Matters series.

Together, we are working hard to build a library of step-by-step instructions on common outboard motor repair and maintenance tasks.