Oberdorfer 402M-03 Bronze Flexible Impeller Pump with 1-1/4" Barb Ports and Single-Groove Pulley
The Oberdorfer 402M-03 is a bronze flexible impeller pump built for dependable engine cooling and raw water circulation. Fitted with 1-1/4" barbed inlet and outlet ports and a single-groove drive pulley, it's designed to bolt onto a belt-driven system and get to work moving water at rates up to 36 gallons per minute. The all-bronze housing resists corrosion in fresh or salt water, while a neoprene impeller and a high chrome nickel stainless steel shaft keep the internals turning smoothly even after years of service.
Inside, a mechanical carbon ring seal with a ceramic face keeps water where it belongs, and two sealed ball bearings, protected by Teflon barrier seals, carry the load without binding up. The cover attaches with an O-ring rather than a gasket, so servicing the pump doesn't mean scraping off old gasket material every time the impeller needs a look. A reversible wearplate extends the working life of the pump chamber, and because the impeller and cam are both easy to pull, routine maintenance stays quick and straightforward.
This pump was originally engineered for marine engine applications, including Chevrolet 327/427 blocks and John Deere JD6404 DR-15 setups, but its rugged bronze construction and belt-drive design make it just as useful anywhere a reliable, pulley-driven transfer pump is needed for engine cooling or general fluid circulation. Whether it's powering a boat's raw water system or standing in for a worn original pump, the 402M-03 is built to run hard and keep running.
Key Features
- All-bronze body and cover for corrosion resistance in fresh and salt water
- Neoprene flexible impeller for efficient pumping action
- High chrome nickel stainless steel shaft for strength and wear resistance
- Mechanical carbon ring seal with ceramic face for a reliable, leak-resistant barrier
- Two sealed ball bearings with Teflon barrier seals for smooth, long-lasting rotation
- O-ring seal between body and cover eliminates gasket replacement hassles
- Reversible wearplate extends pump chamber life
- Single-groove pulley for straightforward belt-drive installation
- Easy impeller and cam access for fast maintenance
Applications
- Marine engine raw water and cooling systems
- Belt-driven engine cooling on Chevrolet 327/427 and compatible blocks
- John Deere JD6404 DR-15 and GMC Toroflow marine engine setups
- General industrial and agricultural fluid transfer where a durable bronze pump is needed
- Replacement or upgrade for worn belt-driven cooling pumps
Specifications
- Port Size: 1-1/4" barbed inlet and outlet (hose slip-on)
- Pulley: Single-groove (A-groove), belt driven
- Maximum Flow Rate: Up to 36 GPM at 3000 RPM
- Pressure Range: Up to 34.6 PSI
- Temperature Range: 40°F to 140°F
- Suction Lift: Up to 15 feet when the impeller is wet
- Housing Material: Bronze
- Impeller Material: Neoprene rubber
- Shaft Material: High chrome nickel stainless steel
- Seal Type: Mechanical carbon ring seal, ceramic face
- Bearings: Two sealed ball bearings
Frequently Asked Questions
Q: Can the Oberdorfer 402M-03 be used with salt water?
A: Yes. The bronze housing and neoprene impeller are built to handle both fresh and salt water, which is why this pump is a common choice for marine raw water cooling systems.
Q: What size belt does the 402M-03 pulley take?
A: The pump ships with a single-groove (A-groove) pulley. Match your belt to the groove profile shown on the pump's dimension drawing, and keep it snug enough to avoid slippage without over-tightening.
Q: Can the impeller be replaced without removing the whole pump?
A: Yes. The cover is held on with screws and sealed with an O-ring rather than a gasket, so the impeller and cam can be swapped out in place without disturbing the plumbing connections.
Q: Is the 402M-03 self-priming?
A: It can lift water up to 15 feet when the impeller is wet, as long as the suction line is airtight. A foot valve on the suction side is recommended to help it prime reliably.
Q: What happens if the pump runs dry?
A: Running the pump without liquid quickly burns up the neoprene impeller, since the blades rely on the pumped fluid for lubrication. Avoid dry running and drain the pump before freezing temperatures to protect the impeller.
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