How to Clean a Bilge Pump on a Boat

Boat bilge pumps, like any machinery, require regular maintenance and cleaning. A bilge pump that is clogged or damaged may not work, which could mean that your boat sustains damage or even sinks in extreme cases. Knowing what your bilge pump does and how to clean it properly is essential to prevent this. 

What is a Boat Bilge Pump?

Boat bilge pumps are small pumps installed in your boat’s bilge wells that remove excess water from leaks, spills, and drainage systems. In the case of corrosive water from leaks and spills, the bilge pump will remove this and keep your boat from destabilizing or forming blisters on the fibreglass surfaces. In extreme cases, the bilge pump could save your life if your boat starts to take on water and sink.

The number of bilge pumps you need will depend on the size of your boat, but it’s recommended that you have 3 to 4 pumps onboard.

There are two basic types of electric bilge pumps: manual and automatic.

Manual bilge pumps are affordable, easy to install, and easy to maintain. In addition, you can install a float switch and make your manual bilge pump more automatic. Manual pumps are best for smaller recreational crafts.

Automatic bilge pumps have a float switch that activates the pump when the water levels inside the bilge are high enough. Automatic bilge pumps are necessary for boats over 20 feet long that feature sleeping bunks. 

4 Types of Bilge Pumps

Not all bilge pumps are created equal. Aside from size, capacity, and type, there are 4 styles:

  1. Reciprocating
  2. Centrifugal
  3. Flexible Impeller
  4. Diaphragm

A Reciprocating Bilge Pump is a positive displacement pump which traps a specific volume of liquid and forces it into the discharge hose. Reciprocating bilge pumps are able to run dry and so pump virtually all water out of the bilge well. However, they have a lower overall capacity and are not well suited to handling debris.

Centrifugal Bilge Pumps are the most common type. These pumps use rotating impellers that push the bilge water into the discharge hose. Centrifugal bilge pumps are low cost, high capacity and can handle smaller debris. 

Flexible Impeller Pumps differ from centrifugal pumps. They have a rubber impeller with a curved shape caused by squeezing the pump casing. These are self-priming positive displacement pumps so that they can remove virtually all bilge water and debris. In addition, flexible impeller pumps should not run dry, unlike a reciprocating bilge pump. 

Diaphragm Bilge Pumps are another type of positive displacement pump. They are best suited for small to medium boats, as they don’t require priming and can be run dry. This type of pump efficiently manages to push water up and out of the discharge hose, but it struggles with debris.

How to Clean a Boat Bilge Pump

The most important part of maintaining a clean bilge pump is prevention, but an occasional cleaning will still be necessary to keep it working well. Cleaning the pump is about as pleasant as wiping down a household bathroom, but these steps should make it easy.

First, here’s what you will need to clean your boat’s bilge pump:

Have you got everything you need? Great! Now here’s how to clean a boat bilge pump.  

  1. Locate and open the access panel close to your bilge pump. This panel is toward the aft of your boat.
  2. Clear away any physical debris from the bilge area, reaching as far forward as possible. 
  3. Ensure the pump activation switch is off and disconnect the pump from the boat’s wiring harness.
  4. With your screwdriver, loosen the clamp holding the discharge hose onto the pump before removing the hose.
  5. Twist the top of the pump counter-clockwise until it is free of the strainer base.
  6. Once you have removed this part of the pump, grasp the bottom and twist the top counter-clockwise until it comes away from the lower casing.
  7. Clear away debris from both parts of the pump. 
  8. Vacuum the entire bilge area of your boat, including the strainer base of the pump.
  9. Take the pump halves away from the boat and use your vinegar – or cleaner – and a scrub brush to remove mold or dirt from your bilge pump.
  10. Rinse the pump with clean, fresh water, keeping the wires dry.
  11. Spread a thin layer of marine grease onto the O-ring seal in the pump.
  12. Reattach the two halves of the pump. If the pump is not positioned as before, you may have difficulty reconnecting the discharge hose.
  13. Position the clamp over the discharge hose and insert the hose into the pump.
  14. With your screwdriver, tighten the clamp enough that it holds but not so tight that it crushes the hose.
  15. Reconnect the wires. Do not flip the activator and switch it back on until you either check the bilge pump’s performance or your boat is in the water.
  16. Close the access panel.
  17. Pat yourself on the back for a job well done!

If your boat is on a trailer, you might want to test the bilge pump. Put the drain plug in and pour 4-5 gallons of water into the bilge through the access panel. If your pump is automatic, it should activate and remove the water. You can also test the manual switch by turning the switch off. Make sure you know what type of bilge pump you have and whether it’s able to be run dry.

Cleaning boat bilge pumps may be an undesirable job, but fortunately, it only needs to be done once a year. Together with regular parts maintenance, cleaning will keep your bilge pump working. 

Don’t have what you need to clean or repair your boat bilge pump? A quick visit to our Marine Store will provide everything you might need to maintain your craft.