Where is the impeller/water pump on my early model blueband mercury 20Hp outboard?
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Located just atop the lower gearcase assembly, they`re easy to access and service, too. The pump houses a rubber impeller that`s keyed to the engine driveshaft. Water enters the lower gearcase through inlets on the sides of the gearcase, just above the propeller shaft area.
Explanation: The impeller is mounted on one shaft or different shaft. A multistage centrifugal pump has more than two impellers. The multistage centrifugal is similar to the centrifugal pumps working.
If you see excessive swelling, noticeable wear and/or cracks, or one or more of the impeller vanes have broken off, replace the impeller pump immediately. You also need to replace the impeller if the vanes are not making contact with the pump body. Impeller pumps work best when you run them on a regular basis.
The heart of the cooling system of your vehicle is the water pump, and as a key part among its components to carry out its function, there is the impeller.
How Often Should You Change the Water Pump On Mercury Outboard? In most cases, you won`t need to replace the water pump unless the housing is damaged. Instead, replacing the water pump impeller every three years or sooner should avoid most water-pump-related issues and keep your outboard running in excellent condition.
If your impeller fails, the water pump cannot pull in water, and your engine will overheat – and potentially leave you stranded far from shore, adrift with no power.
Impellers are attached to a shaft that is connected to a motor.
The impeller shaft rotates in ball and roller bearings and is either common to the turbine shaft or split in the center and connected by a coupling, which is usually designed for ease of detachment.
All impellers should be changed at a minimum of three years. Some will not make it that long depending on many things, how often it is used… too little and it will deform and tend to dry rot. Use it alot and it will wear out from spinning around in it`s housing.
The water pump is attached directly to the engine block and operates by centrifugal force. If the water pump isn`t working, the coolant will remain stagnant, and the engine will overheat. A modern car engine can withstand slight overheating, but severe overheating can damage it.
MerCruiser impellers should be replaced every three years.
It`s common to find pump impellers with significant surface damage. The three most common causes of surface damage are erosion, corrosion and cavitation.
Impeller failure
Erosion is caused by the suspended particles in the fluid being pumped. Impeller failure can also result from corrosion or cavitation. Corrosion is caused by chemical reactions between the pumped fluid and the metals used in pump manufacture.
A grinding or droning sound will, again, indicate a problem with the bearings in the motor, while a scraping sound could indicate the impeller is damaged or dislodged.
How to Tell if Your Impeller is Bad. If your boat overheats it could be a sign that your raw water pump isn`t working. One of the first things you should check is the impeller inside the pump. If the impeller is cracked, melted or the vanes have lost their flexibility then it`s time to replace it.
The speed and diameter of the impeller determines the head or pressure that the pump can generate. The rotational speed and height of the impeller blades determines the flow that the pump can accommodate [4, 5]. The design of the impeller diameter is critical because it affect the performance of the centrifugal pump.
Tests prove that Globe`s Run-Dry® impellers outperform standard neoprene or rubber impellers and are guaranteed to run-dry for up to 15 minutes.
How many hours do boat engines last? Well-maintained inboard engines, inboard outboard engines (unless diesel), and outboards have a serviceable, average life of about 1500 – 2000 hours. If you`re looking at a gas-fueled marine engine close to or exceeding 1000 hours, inboard or outboard, proceed with caution.
There are many methods for repairing the impeller of the water pump. There are many methods for repairing the impeller cavitation, such as ARC polymer composite material coating, powder spraying (welding), epoxy resin coating, and rubber and nylon composite material repair, etc.
Impeller Damage
As is the case for the housing of your pump, the impeller is susceptible to damage done by excessive heat during use. Dry running your pump causes friction, and this friction is strong enough to heat up the impeller, causing it to melt.
If the impeller runs backwards, the liquid is still discharged from the pump. This is due to centrifugal forces that move the fluid in the normal direction. Put simply, the flow doesn`t reverse, making reverse rotation hard to detect.
The inlet, or suction side of a pump is the point of lowest pressure in a given pump. For positive displacement pumps, the lowest pressure occurs just prior to rotor meshing; for centrifugal pumps, lowest pressure is near the eye of the impeller.
The action of the impeller increases the fluid`s velocity and pressure and also directs it towards the pump outlet.
Typically when they`re replaced or the pump housing is opened for inspection, they should be lubricated to give them a chance to suck in the water initially without abrading against the sides of the pump. Once water starts flowing through, this will lubricate them.