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Johnson Pump Impeller - Nitrile (F4B) With Glycerine - Small

Johnson Pump Impeller - Nitrile (F4B) With Glycerine - Small


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Johnson Pump Impeller - Nitrile (F4B) With Glycerine - Small.      Ref19: AF-09-810B-9

For the well-being of your boat engine your water cooling pump must be able to supply a minimum specified continuous flow of cooling water. The flexible impeller in your pump, which provides this pumping action, is a wear part. Over time the impeller will lose its ability to maintain the pressure needed for the flow of cooling water and must be replaced.     

A good quality impeller will provide you with many months of problem-free operation. For an impeller of lesser quality the performance can degrade so rapidly that you, at best, must replace the impeller more often; at worst, you could be left adrift with engine damage. 

Remove the impeller with slip joint pliers or a Johnson Pump Impeller.



  • Compatible Pump - F4
  • Material - Nitrile
  • Outer Diameter - 50.8mm
  • Inner Diameter - 12mm
  • Width - 22mm

How to fit a new impeller:




Lubricate the shaft and the inside of the pump body and the end cover. Use Johnson Pump Lubrication to help develop prime and prevent damage from dry-running the pump at initial start-up. Mount the impeller by making a pushing and twisting movement in the rotating direction. Lubricated impellers should not be stored for extended periods of time. The engine should be run after installation of a new impeller to wash out the lubrication. These recommendations apply to any service work on the pump and its components that require the use of lubrication inside the pump for assembly and start-up.

Warning! Do not use any petroleum-based products to lubricate the inside of the pump. Only use Johnson Pump Lubrication. Other products can damage the impeller which will damage the pump and lead to engine failure. Do not run the impeller without water or lubricant; this can cause engine failure or a fire.

1. A vacuum is created as the flexible impeller vanes straighten upon leaving the cam drawing liquid into the pump.

2. The rotating impeller carries liquid from the inlet to the outlet port.  As a consequence of their design flexible impeller pumps can pass fairly large solids.


3. When the flexible impeller vanes regain contact with the cam they bend and the liquid is discharged from the pump in a uniform flow.  Liquids can be pumped in the opposite direction by reversing the rotation of the pump.

For more information, please click here. 

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