By Chris Butler
Each year customers come to my dealership and ask what needs to be done to their boat for the upcoming season. Most people understand the importance of regular maintenance on their boat, such as changing the oil in the engine and lower unit, but they struggle with changing their water pump. I think the reason for this is because they don’t understand the difference between the water pump in their car and the one on their outboard motor.
A vehicle’s water pump is a closed loop with freshwater and an anti-freeze. Closed loop means there should not be anything being pumped through the system from the outside environment. The pump itself is under the hood of your vehicle, and the outside housing is never submerged, unless you wreck your car into the water. You change your coolant about every 65,000 miles, and in some vehicles they recommend 100,000 miles. I looked in the maintenance book for my truck and couldn’t find a time they recommend changing the water pump, only the coolant. Usually, when a vehicle’s water pump fails or starts to fail, there will be puddles of anti-freeze that a person will notice on the ground. A driver may also notice the car running hot by the temperature gauge. In some cases the vehicle will completely overheat, spilling coolant everywhere, but most drivers stop the vehicle before any major damage is done.
An outboard water pump is very different, especially when you consider saltwater. If you think about it, a water pump spends almost all of its running life in one of the most corrosive environments on the planet: saltwater. This coolant is not only saltwater, but whatever may be in that water, including sand, mud, shells, bags and marsh grass. The entire housing is submerged in this environment, as well.
The way an outboard water pump works is fairly simple. It has either a metal or plastic housing with a rubber impeller that looks like a starfish. It rotates at the speed of the driveshaft and draws water through it and sends it to the rest of the motor to keep it cool. If it sucks up sand or mud, it sends it through the rest of the engine, and, in most cases, those items exit out the “pee hole.”
Over time, this debris takes a toll on the water pump and housing, causing the pump to lose flow or volume. This causes the engine to run hotter and eventually will cause the engine to overheat. The problem with an overheat situation on an outboard is that once the pump quits, all coolant (saltwater) leaves the engine because of gravity. This can cause the temperature of an engine to spike and cause internal damage, which is always costly.
I recommend to most customers to change their water pump every other year, and if you fish in shallow water and pump a lot of sand and mud, then I recommend every year. The cost on average is $250, but a water pump keeps a $10,000 to $20,000 piece of equipment running correctly. The other benefit of changing the water pump every other year is it allows either you or the technician to clean and lubricate the mounting bolts for the lower unit. I have seen my technicians spend eight hours (which the customer is paying for) on breaking a lower unit loose to get to a water pump because the customer thought they were saving money by not changing their water pump for five years. However, they failed to realize that salt was building up in the mounting bolts and causing them to swell.
A little preventive maintenance will save you big in the future. See you on the water.