Oberdorfer 402M Bronze Flexible Impeller Pump - Engine Mount Configuration
Reliable engine cooling starts with a pump built to handle constant duty without breaking down, and that's exactly what the Oberdorfer 402M delivers. This engine-mounted, bronze-bodied flexible impeller pump was originally engineered for demanding marine powerplants, including Daytona Marine engines built on Chevrolet 327 and 427 blocks, along with American Marine Ltd. setups using John Deere JD6404 DR-15 and GMC Toroflow blocks. Its all-bronze construction resists corrosion from fresh water, salt water, and mild chemical exposure, making it a dependable choice anywhere an engine-driven cooling circuit needs to keep running under pressure.
What makes the 402M stand out is how it's built to mount directly onto the engine and draw power straight from the drive system, eliminating the need for a separate motor. The neoprene impeller moves up to 36 gallons per minute through a 1 1/4-inch hose connection, and the pump is self-priming with up to 15 feet of suction lift once the impeller is wet. An O-ring seal between the body and cover keeps things leak-free without relying on a gasket, while the stainless steel shaft and sealed design help the unit shrug off years of heat cycling and vibration.
Beyond its original marine applications, the 402M's straightforward belt-driven design and bronze housing make it adaptable to other engines using compatible blocks, and it's a common go-to for anyone rebuilding or upgrading an engine-mounted cooling system. Whether it's powering a boat's raw water circuit or supporting an industrial engine that needs the same kind of rugged, corrosion-resistant pumping action, the 402M is built to be mounted, belted up, and put to work with minimal fuss.
Key Features
- All-bronze body and cover for maximum corrosion resistance
- Neoprene flexible impeller for reliable self-priming operation
- O-ring seal between body and cover eliminates gasket issues
- High-grade stainless steel shaft for long service life
- Engine-mounted design driven directly off the engine's belt system
- Operates in any mounting position
- Special mounting holes cast into the extended cover for direct engine attachment
Applications
- Marine engine raw water and cooling circuits
- Daytona Marine engines using Chevrolet 327 and 427 blocks
- American Marine Ltd. setups using John Deere JD6404 DR-15 blocks
- GMC Toroflow 63701893 block cooling systems
- Industrial and off-highway engines requiring belt-driven coolant circulation
- General-purpose engine-mounted liquid transfer where neoprene compatibility is suitable
Specifications
- Port Size: 1 1/4" ID hose slip-on connection
- Flow Rate: Up to 36 GPM
- Impeller Material: Neoprene
- Seal Type: Lip seal / mechanical carbon-ceramic face seal (configuration dependent)
- Shaft Material: Stainless steel
- Temperature Limit: 40°F to 180°F (impeller life may be affected at temperature extremes)
- Max Shaft Speed: 3,000 RPM
- Suction Lift: Up to 15 feet when impeller is wet
- Body Construction: Bronze
Frequently Asked Questions
Q: Can the Oberdorfer 402M pump run dry for short periods?
A: No, the pump should never be run dry. The neoprene impeller relies on the pumped liquid for lubrication, and running without fluid will quickly burn up the impeller.
Q: What liquids is the 402M safe to pump?
A: It's compatible with fresh water, salt water, and mild chemicals that don't degrade neoprene. Severe solvents and acids should be avoided.
Q: Does the 402M need to be mounted in a specific orientation?
A: No, the pump is designed to operate satisfactorily in any mounting position, giving flexibility for different engine layouts.
Q: How is the pulley installed or removed on the 402M?
A: The pulley uses a tapered bushing secured with three cap screws, tightened evenly and progressively to a maximum of 75 inch-lbs. Removal uses the same screws threaded into dedicated removal holes to press the pulley off the bushing.
Q: What happens if the pump sits idle in freezing conditions?
A: Liquid left inside the pump can freeze and cause damage, so it should be drained by loosening the cover screws, or protected with a methyl alcohol-based anti-freeze compound.
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