Detroit Diesel 3-71 Non-Turbo - 2 Val Engine Water Pump - Aftermarket

Parts for Detroit Diesel 371 Non-Turbo (2-Valve Head Type) – Engine Water Pump Section

Engine Overview and Cooling System Function

The Detroit Diesel 371 Non-Turbo engine is a single-cylinder variant of the famous 71-Series two-stroke line that includes the 471 and 671. Compact, durable, and efficient, the 371 engine was engineered for light industrial and marine auxiliary use where steady torque and long service intervals were priorities. Like all 71-Series engines, the 371 depends on a precisely balanced cooling system to maintain optimal performance.

The water pump is the heart of that system, pushing coolant through the cylinder block, oil cooler housing, and thermostat before returning it through a radiator or heat exchanger. Even slight wear on impellers, bearings, or seals can reduce flow and lead to overheating, especially in continuous-duty environments. Diesel Pro Power supplies complete, high-quality replacement components for every part of this system—new pumps, gaskets, thermostats, fittings, hoses, and clamps—all engineered for direct fit and long service life.

Every part on this page is in stock and ready for fast worldwide shipping, ensuring operators can restore full cooling efficiency without long downtime.

Fresh Water Pumps for Detroit Diesel 371 Engines

Right-Hand Rotation Fresh Water Pump

This new right-hand rotation water pump is designed specifically for Detroit Diesel 371, 471, and 671 engines. It delivers factory-level coolant flow to protect against overheating in continuous-duty service.

Type: New replacement pump, not remanufactured
Rotation: Right-hand (clockwise when viewed from the rear of the engine)
Construction: Heavy-duty cast housing, balanced impeller, precision bearings, and shaft seal for consistent flow
Application: Industrial, generator, and marine propulsion systems using the 371 non-turbo configuration
Performance: Maintains optimal coolant circulation under full-load operation and ensures stable operating temperature

This pump is a direct replacement that bolts on without modification. Diesel Pro Power ensures every new unit is pressure-tested and balanced for long-term reliability.

Left-Hand Rotation Fresh Water Pump

The left-hand rotation pump is engineered to meet the same durability standards as the right-hand version but is oriented for opposite engine rotation. Many marine twin installations require left-hand rotation for port-side engines, making this pump the correct solution for those setups.

Rotation: Left-hand (counter-clockwise viewed from rear)
Fitment: Detroit Diesel 371, 471, and 671 engines in left-hand rotation configuration
Design: Robust casting and impeller geometry optimized for steady coolant delivery in marine service
Quality: Every pump is tested for correct flow rate and sealing integrity before shipping

Both right- and left-hand pumps are manufactured to OEM specification and shipped with a full warranty, ensuring dependable cooling system operation.

Gaskets, Seals, and Flanges for Water Pumps

Water Pump Gasket

A proper gasket seal is essential to prevent leaks between the pump housing and engine block. This Detroit Diesel water pump gasket is made from high-temperature composite material resistant to coolant additives and pressure cycling. It ensures a tight, leak-free seal for thousands of hours of service.

Water Pump Flange

The pump flange supports the connection between the water pump outlet and the engine’s coolant plumbing. Precision-machined for a 1.558-inch inner diameter, this flange maintains correct alignment under high vibration conditions. Durable surface finish resists corrosion from coolant and environmental moisture.

O-Ring for Pump Outlet

The O-ring for the fresh-water pump outlet provides a flexible, high-temperature seal at the discharge side of the pump. Manufactured from coolant-resistant synthetic rubber, it helps maintain system pressure and prevents weeping at the outlet connection.

Cover Gasket and Housing Gaskets

Additional gaskets, including the water pump cover gasket and thermostat housing gasket, are available to complete the cooling system service. These precision-cut seals are designed to withstand high temperatures and repeated expansion cycles without deforming or leaking.

Water Seals

Diesel Pro Power also stocks water seals used throughout the cooling manifold and oil cooler housing. Available in multiple outside diameters (2-3/16", 2-1/2", and 2-3/4"), each seal features an inner lip to provide superior sealing between cast-iron mating surfaces.

Thermostats and Temperature Control Components

Detroit Diesel Thermostat

The correct thermostat ensures that coolant remains in the block long enough for the engine to reach its designed operating temperature. The Detroit Diesel 371 thermostat opens at 173°F, maintaining ideal temperature for fuel efficiency and lubricant protection.

Design: Direct OEM-style fit
Calibration: 173°F opening point for optimal heat balance
Use: Fits 371, 471, and 671 non-turbo configurations

Thermostat Gasket and Housing Gasket

Complementary gaskets seal the thermostat and housing cover to prevent coolant seepage during expansion and contraction cycles. Each gasket is precision-cut to Detroit Diesel specifications for perfect alignment and long-term reliability.

Radiators and Related Components

Detroit Diesel Radiator for Industrial Engines

For stationary and industrial engines, Diesel Pro Power offers a complete replacement radiator for the 371, 471, and 671 engines. Each radiator core is built with heavy-gauge copper and brass designed for superior thermal transfer and extended life.

Construction: Industrial-grade tanks and tubes for high vibration resistance
Cooling Capacity: Meets or exceeds OEM flow specifications
Fitment: Direct replacement for Detroit Diesel 371 industrial applications

Radiator Caps and Necks

The radiator cap maintains system pressure—critical for raising the boiling point of coolant. Options include small and large cap necks with precise inside diameters to match original housings.

Small Cap: 7-lb pressure rating; ideal for compact cooling systems
Cap Necks: Available in 1.63-inch, 2.17-inch, and larger diameters for various radiator configurations

All radiator components are designed to withstand constant thermal cycling without losing sealing tension.

Water Bypass Tubes and Fittings

Water Bypass Tube – Thermostat Connection

The water bypass tube allows limited coolant circulation when the thermostat is closed, preventing localized overheating in the cylinder head during warm-up. Constructed from corrosion-resistant steel, this tube ensures steady coolant routing and easy installation.

Drain Fittings

Draincocks are essential for proper maintenance of the cooling system. Diesel Pro Power offers both 3/8-inch and 1/4-inch threaded drain fittings for the 371, 471, and 671 engines. They provide a reliable means of draining coolant for seasonal service or repairs.

Radiator Service Accessories

Radiator Cleaner

To maintain system efficiency, Diesel Pro Power supplies radiator cleaner formulated to remove rust, scale, and oil residue from internal cooling passages. Regular use improves heat transfer and prevents thermostat sticking. Available for ground shipping in the USA and Canada.

Temperature Switch

A temperature switch compatible with Detroit Diesel, Cummins, and Caterpillar engines ensures reliable over-temperature monitoring. It activates at 205°F and uses a 1/2-inch NPT thread for universal installation in coolant manifolds or thermostat housings.

Coolant Hoses and Clamps

Silicone Coolant Hoses

Silicone hoses are a key upgrade for Detroit Diesel 371 operators seeking longer service life and improved heat resistance compared to standard rubber hoses. Diesel Pro Power stocks a full range of silicone coolant hoses in 1-foot sections with inside diameters from 3/4" to 4".

Each hose is reinforced for high pressure and temperature operation, resistant to oil mist, and ideal for marine or industrial environments.

Available diameters include:

3/4" – For small coolant lines or bypass circuits
1", 1-3/4", 1-7/8" – Common main and return lines
2", 2-1/8", 2-1/4", 2-3/8", 2-1/2", 2-3/4" – Standard radiator and water pump connections
3", 3-1/2", 4" – Heavy-duty and marine main coolant hoses

These hoses meet SAE J20 Class A standards and can handle extreme heat and vibration typical of Detroit Diesel engines.

Hose Clamps

To secure every hose connection, Diesel Pro Power offers a complete line of stainless-steel hose clamps. Each clamp provides an adjustable diameter range to fit standard coolant and fuel hose sizes.

Small clamps: Fit 9/16" to 1-1/16" hoses for bypass and return lines
Medium clamps: Fit 1" to 1.5", 13/16" to 1-3/4", and 11/16" to 1-1/4" ranges
Large clamps: Cover 1-5/16" to 2-1/4", 1-9/16" to 2-1/2", 2-5/16" to 3", and up to 3.5"

All clamps are corrosion-resistant, providing secure, vibration-proof sealing.

Monitoring and Instrumentation

Mechanical and Electric Gauges

Accurate temperature and pressure monitoring help protect your Detroit Diesel 371 engine. Diesel Pro Power supplies both mechanical and electric gauges:

Mechanical Gauges (Standard and Alarm Models): Provide real-time readings without electrical power, ideal for marine or generator applications.
Electrical Gauges (12- and 24-Volt): Suitable for control panels and remote monitoring systems.

Each gauge is calibrated for Detroit Diesel operating ranges and designed for reliability in vibration-intensive environments.

The Diesel Pro Power Difference

Complete Detroit Diesel Cooling Solutions

Diesel Pro Power has become the go-to source for legacy Detroit Diesel owners seeking quality, availability, and expertise. Every product on this page—whether a full water pump, thermostat, gasket, or coolant hose—is backed by years of field testing and customer trust.

Why Operators Choose Diesel Pro Power

Global Reputation: Trusted by over 40,000 satisfied customers across more than 180 countries.
Premium Quality: Every pump, seal, and accessory meets or exceeds Detroit Diesel factory standards.
Comprehensive Catalog: Parts are organized by engine model and system for quick identification.
Fast Worldwide Shipping: Orders ship quickly to marinas, ports, industrial sites, and maintenance facilities worldwide.
Expert Support: Experienced technicians assist with part selection, rotation direction, gasket compatibility, and installation guidance.

Choosing Diesel Pro Power means more than buying parts—it’s securing reliability, performance, and longevity for your Detroit Diesel 371 Non-Turbo engine.