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Flexible Impeller pump max flow 36 GPM max pressure 34.6 PSI 402M

Flexible Impeller Pump - 402M

Designed for Daytona Marine Engine using Chevrolet Blocks NO 327 and 427. Designed for American Marine LTD. Using John Deere Block NO JD6404 DR-15 and GMC Block Toroflow 63701893. Adaptable to other engines using these blocks.

These Flexible Impeller pumps are made of high quality bronze of maximum corrosion resistance. All shafts consist of stainless steel grade 303. Top of the line models have ball bearings and mechanical seals while others have bronze or carbon bearings and lip type seals. Impellers are made of Neoprene Rubber. Nitrile impellers are available as an option. Flexible blades on the periphery of the impeller provide the pumping action. While the impeller rotates the liquid between the blades is continuously squeezed out into the discharge port by a machined in cam located inside the pump chamber.

The impeller must be replaced if it is worn out or has been damaged by debris or by running the pump dry. Symptoms of a defective impeller are low pumping pressure and low flow causing overheating of the boat engine. Poor pump performance can also be caused by slippage of V-belts, so belts should be checked for tightness. To replace the impeller remove screws and cover, pull out the impeller with needle nose pliers or two screwdrivers. Be careful not to dent the pumping chamber with these tools. When inserting new impeller, line up key slot in impeller with the key in the shaft. Use oil on shaft and avoid forcing the impeller onto the shaft. The impeller should also be removed for storage periods to prevent the blades from taking a permanent set.

If water drips from the weep hole or from the area where the shaft exits the pump, the seal is defective and must be replaced. While the Polytetrafluoroethylene (PTFE) barrier seal provides a first line of defense, prolonged running of the pump with a leaky seal can destroy the ball bearings resulting in catastrophic pump failure and engine shut-down. For seal replacement, the pump must be removed from the engine and disassembled in order to gain access to the seal area. Where mechanical seals are used, both components (stationary and rotating member) must be replaced at the same time. Lip seals must be pushed out of their press-fitted position and new seals pressed into place, using a sealant on the outside of the lip seal housing. Refer to exploded view drawings for seal location and part numbers for ordering purposes.


  • Bronze Construction - Corrosion Resistance
  • Reversible Wearplate
  • Polytetrafluoroethylene (PTFE) Barrier Seals Protecting Ball Bearings
  • Mechanical Carbon Ring, Ceramic Face Main Pump Seal
  • Two Sealed Ball Bearings Spaced for Maximum Load Ability
  • Large Vent & Drain Openings Separate Seal & Bearing Areas
  • Shaft Slinger for Additional Bearing Protection
  • Neoprene Impeller
  • High Chrome Nickel Stainless Steel Shaft
  • O-Ring Seal Between Body and Cover Eliminates Gasket Problems
  • Impeller & Cam Easily Replaced


Select proper belt size to match pulley groove as shown on dimension drawing on back. Belt must run sufficiently tight to prevent slippage. Do not over tighten. Pump will operate satisfactorily when mounted in any position. Special mounting holes are provided as part of extended cover casting.

Direction of shaft rotation determines inlet and outlet ports (see dimension drawing). Prior to installation, rotate the pump manually in direction of rotation to set flexible blades in direction desired.

Rubber impellers generate high rubbing friction unless lubricated by liquid being pumped. DO NOT RUN DRY. Lack of liquid will cause impeller to burn up.

The pulley is normally installed at the factory. If field service requires pulley removal and reinstallation, proceed as follows:

Pulley Removal: Loosen and remove the three three cap screws in the tapered steel bushing. Thread the three cap screws in the tapped removal holes, and progressively tighten each one until the aluminum pulley is loose on the tapered steel bushing. If the steel bushing won’t slip off the pump shaft, wedge screwdriver blade in saw cut to expand and overcome tightness.

Pulley Installation: Align the pulley groove with the belt centerline. Tighten the three bushing cap screws drawing the tapered steel bushing into the aluminum pulley and thereby tightening the steel bushing onto the pump shaft. Tighten the screws evenly and progressively. This insures an even draw down to eliminate pulley wobble. DO NOT tighten each screw independently. The ultimate maximum recommended torque is 75 inch-lbs.
Note: For two groove pulley, see 402M-06 (7562) - consult factory.


Liquids compatible with neoprene can be pumped including fresh and salt-water solution and mild chemicals. Do not pump severe solvents or acids. When possible, flush pump with fresh water after each usage.

Extremes of cold and heat will affect impeller life. Limits of 40°F to 180°F should be observed. Do not allow liquid in pump to freeze. Drain pump by loosening cover screws. Use methyl alcohol based anti-freeze compounds such as Zerex, Shell Zone, Pyro Permanent, Permagard, or Dowgard.


Suction lift of 15 feet is possible when impeller is wet. Suction lines must be air tight in order for pump to self-prime.