Outboard Lower Unit Not Pumping Water? How to Fix It

If your outboard lower unit is not pumping water, it can lead to serious engine issues like overheating. The water pump is responsible for circulating water through your outboard motor to keep it cool.

When it’s not working properly, your engine could overheat and cause expensive damage. This guide will help you troubleshoot and fix your outboard water pump issues easily.

Reason Your Outboard Lower Unit Not Pumping Water?

There are several reasons why your outboard motor lower unit may not be pumping water

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The most common causes include:

• Clogged water intake: Debris or algae can block the water intake, preventing water from reaching the pump.
• Damaged impeller: If the impeller is worn or damaged, it won’t be able to pump water effectively.
• Faulty water pump: A malfunctioning water pump can fail to circulate water, causing overheating.
• Airlock in the system: Sometimes, air can become trapped in the water pump system, blocking water flow.

Step-by-Step Guide to Fixing Your Outboard Lower Unit

1. Check the Water Intake for Blockages

The first thing to check if your outboard lower unit isn’t pumping water is the water intake. The intake is typically located near the bottom of the lower unit.

Inspect it for any debris or algae that might be clogging the intake. Clean out any visible blockages using a brush or hose.

Ensuring water can flow freely into the intake is crucial for proper pump function.

2. Inspect the Impeller

The impeller inside your outboard motor water pump is responsible for circulating the water. Over time, the impeller can become damaged, cracked, or worn out. If the impeller is damaged, it won’t pump water efficiently.

Remove the lower unit to access the water pump, and inspect the impeller for signs of damage. If necessary, replace it with a new one.

3. Check the Water Pump Housing and Seals

Sometimes, the water pump housing can become corroded, or the seals can wear out, preventing proper water circulation. Inspect the housing for any cracks or damage and ensure the seals are intact. If the housing is damaged, it’s important to replace it to ensure the water pump works properly.

4. Look for Airlocks in the System

An airlock in the water pump system can prevent water from circulating. To fix this, try starting the engine while it’s submerged in water. This can help push the air out of the system.

If the problem persists, you may need to remove the water pump and reassemble it to ensure all air has been released.

How to Prevent Future Issues with Your Outboard Lower Unit

Regular maintenance can help prevent your outboard lower unit from losing its water-pumping ability. Here are some tips:

• Regularly clean the water intake: Make sure to inspect and clean the intake area frequently to prevent debris buildup.
• Replace the impeller regularly: Even if the impeller isn’t showing obvious signs of wear, it’s good practice to replace it every 1-2 years or as recommended by the manufacturer.
• Inspect seals and housing: Ensure the seals and housing are in good condition. Replace them if necessary to avoid leaks and malfunctions.
• Use the motor in clean water: Operating in shallow or dirty water can introduce debris into the intake, affecting the pump’s ability to circulate water.

Conclusion: Keep Your Outboard Motor Running Smoothly

If your outboard lower unit is not pumping water, don’t panic! By following these troubleshooting steps, you can identify the problem and get your water pump working again. Regular maintenance and inspections are key to ensuring your outboard motor stays in great condition and avoids overheating.

Whether you have a Mercury or Yamaha motor, these tips will help you keep your motor running smoothly for years to come.