Marine Water Pumps

Marine water pumps are responsible for keeping the boat’s engine cool while it is in operation. The way marine water pumps work is by pumping raw water from the bottom of your engine over the top of the engine continually so that the engine stays cool. Marine water pumps are made from a rubber plastic material so it is not going to last as long as other engine parts. In fact, most people who use their boats on a regular basis find that they have to replace the pump once a year, sometimes more or less depending on how often you use your boat and the type of conditions you use your boat in. Do not mistaken marine water pumps as the same as sea water pumps. The latter are used mainly for both indoor or outdoor sea water aquariums.

Marine water pumps go through a lot of abuse, even if you don’t do it intentionally. Almost everything that enters the water pump, including high turbidity water, is bad for the water pump. Even if you avoid shallow areas so that sand and mud doesn’t get sucked into the water pump, but sometimes you don’t know you have hit that area until it’s too late. All of the sand, mud, and small shells that are sucked into the water pump act like sand paper against the impellers. Marine water pumps are vital to boats because without them boats cannot function properly, which is why it is recommended that you change the pump every year. Luckily, changing marine water pumps is easy enough that you can probably do it yourself.

Steps To Changing Marine Water Pumps

1. Step One
   
   Use the right size wrench, which will depend on what outboard you have, to take off the six bolts on the bottom of the outboard. The easiest way to tell if they are the right bolts is they are the ones located right below the anti-cavitiation plate.
   
   
2. Step Two
   
   You will need to remove the trim tab located on the bottom of the anti-cavitiation plate. After the tab has been removed, keep it and the bolt to it separated from the other six bolts because they are not the same size.
   
   
3. Step Three
   
   The last bolt you have to remove is located underneath the trim tab. Once you remove this bolt the lower part of the outboard is ready to come off so be prepared. Use either body pressure or a jack stand to hold the lower unit in place until you have got the bolt out. Once you are ready, take out the lower unit carefully, while paying close attention to the motor and shift shafts. You might need to use a rubber mallet to get started, but this should also be done with care before moving onto the next steps on changing marine water pumps.
   
   
4. Step Four
   
   Set the lower unit on a worktable so that you can begin taking out the old water pump and placing it with the new one. The water pump will be covered with a plastic housing that is held on by four bolts. Carefully remove the bolts and plastic housing so that the water pump is exposed.
   
   
5. Step Five
   
   Remove the water pump impeller by sliding it over the motor shaft. Then remove the steel plate and gasket that the water pump is sitting on top of. If any of these pieces are stuck carefully use a screwdriver to remove them.
   
   
6. Step Six
   
   The plastic housing for marine water pumps also contains a stainless steel cup that needs to be removed, as well as the O-ring. On the motor shaft you will see a key way that needs to be removed, which might require the use of a flathead screwdriver.
   
   
7. Step Seven
   
   After laying out all of the parts for your new water pump you will want to put the pieces back on. You will want to start with the gasket for the lower unit and then place the steel plate over the gasket. You will put in the new key way and then the new impeller. Once you have placed the new O-ring around the edge of the stainless steel cup, place the assembly into the plastic housing. Now place the plastic housing back in place and the new water pump has been successfully installed.
   
   
8. Step Eight
   
   Now you just have to reassemble the lower unit back in place. Before replacing the lower unit you must use marine grease on both shafts. You will also need to make sure that the rubber hose for the speedometer is accessible so it is easy to connect as you are putting the lower unit back on. Once everything is flush you will want to install the trim tab bolt first and then the other six bolts to hold everything in place. Make sure you grease the bolts before tightening. The bolts shouldn’t be over tightened, but you want them to be secure.
   
   
9. Step Nine
   
   Marine water pumps must be tested before you put the boat back in the water to use. However, you will want to test the outboard in water to ensure everything is working properly. Rather than using the lake you can use a tub of water that is deep enough for the outboard. Look for the pee stream and check both gears. Consult the professionals whenever you’re in doubt about installation of marine water pumps.