A little glycerin or dish soap will make it easier to slide on the pump cover and provide lubrication for a second or two before water enters the pump and lubricates the blades. Use neoprene impellers to cool the engine and pump fresh and saltwater. Inboard sterndrive motors typically include a flexible impeller raw water pump. Polyurethane impellers are used for ballast pumps on boats towing wakeboards.
The water pump is part of the boat’s cooling system. It takes in water and passes it over the engine so the water can absorb the heat generated therein. As the water does so, it becomes hotter and eventually turns to steam. At that point, the steam escapes through the boat’s exhaust system.
Marine engine cooling pumps and water pump impellers help extend the life of your outboard engine. Regular water pump maintenance helps keep your engine running at peak performance and can save thousands of dollars in potential engine damage.
There are many stories that say, “I have had my outboard for twenty years and have never replaced the water pump”; however, it is good preventative maintenance practice to replace the pump and housing at regular intervals. It is important to remember that proper boat maintenance can save a lot of time on the water, especially if we neglect to take care of our engine or, in this case, the water pump.
How Water Pumps Typically Work
In a typical outboard motor, a pump draws water as a cooling agent for the engine. If the impeller fails, the pump cannot pump cold water into the engine, which leads to overheating. If the impeller fails, the pump cannot pump cold water into the engine, which leads to overheating.
If you find that your impeller breaks down first, you can avoid major problems. The impeller usually fails due to dry rot associated with disuse, not overuse.
The outboard can stop pumping water from the canopy, overheat, limit the available RPM, and cause significant damage if not repaired. When this happens, the water flow is cut off, causing engine problems.
The engine is lowered by a pump below the waterline to prevent freezing and damage. Water enters the outboard motor through the lower block, which is below the water level while the boat is moving. Water is sucked in through the lower block by the impeller of the water pump, then forcibly lifted up to circulate through the motor assembly, and finally out through the drainage system.
Cooling water is sucked in through the intake grilles of the lower block to a rubber impeller attached to the drive shaft at the top of the lower block, and through it, it is pumped into the outboard motor. There it is circulated and eventually exits through the propeller again to cool it from the outboard exhaust gases. The orifice of the sensor emits a small visible stream of water after it has passed through the head to help indicate that cooling water is flowing.
Checking for Reliable Water Flow
Check the water inlet grill regularly to make sure nothing is blocking the water flow. Also, if you are using the boat in salt water, be sure to wash the engine and cooling system after each use. Of course, you should also check the wet transom exhaust for proper cooling water flow each time you start the engine.
Before reinstalling the pump, clean the mating surfaces to ensure there are no leaks. Clean the inside of the pump housing making sure it is free of scuff marks or scratches. If this happens, water can flow out of the impeller blades and the pump will not work as efficiently as it should. If this isn’t your first time out of the season and you notice a drop in water consumption, you may have a damaged pump housing or impeller.
Most circulation problems and motor overheating are caused by faulty water pump impellers. The raw water pump is driven by a belt on the engine and includes an impeller that drives the pump. The fan blows cold water into the marine engine to keep it cool while the engine is running.
When the impeller is broken, it shuts off the water supply to the engine and causes it to overheat. When the impeller fails, the pump cannot pump and the motor overheats. This can cause the impellers to overheat and then melt, reducing their ability to carry water to the motor. Water lubricates the impeller, and if it runs dry, the impeller can fail in a matter of seconds.
When the cooling system is filled with water, with no outlet, the impeller simply agitates it without cooling the engine. If it breaks down, the water supply stops, which leads to overheating of the engine. It travels upward through the engine head to circulate in the engine cooling passages.
What Happens When Impellers Malfunction
As the scale builds up to the water flow limiting point, the engine starts to overheat. Jansen and Greenwood agree that running the engine dry, that is, without supplying water to the pump, means instant death of the impeller. “Greenwood says he sees boat owners pushing the engine quickly with a choke at the launch pad just to make sure it’s ready to go when they fall into the water, as well as other people who think they need to start. engine after exiting. the boat out of the water to drain it.
“You may notice a slight flow of water from the pilot on the engine side and this could mean that the technician did not check for debris in the impeller.
Stop the engine immediately if no water flow is visible from the lower rear of the upper engine cover; Problem with impeller, loose outlets, or clogged water supply fitting. When inserting the unit into the center section, make sure that the drive shaft, shift shaft and water pipe are installed correctly.
With the boat engine off, check for debris, such as debris or algae, that may be blocking the water intake. Turn off the engine and check for anything such as weeds or debris that could block the water intake. If the old impeller comes apart and / or you see other debris (sticks, sand, dirt), be careful to blow out all water passages with compressed air to remove debris that could block the water passage. When the engine is restarted, the impeller is badly worn out by silt.
The pump then sucks in water through the gearbox outlets and rises into the housing. The impeller has an inlet that allows water to enter and vanes that push the liquid forward. As the rotating component of a centrifugal pump, the impeller accelerates the fluid outward from the center of rotation. This compression and expansion action is what gives the pump the ability to send water under pressure through the engine’s cooling chambers.
Conclusion
While he was moving forward at full throttle, he had enough water to cool the engine. Some people water their engines with water to cool them down until they get home. This means that there is a small reservoir at the top of the engine that uses a mixture of fresh water and coolant. The raw water is also pumped through a heat exchanger where it absorbs some of the heat from the fresh water and is again discharged overboard.
