Detroit Diesel 671 Non-Turbo (2-Valve Head Type) – Fresh Water Pump & Cooling System Parts Catalog

The Detroit Diesel 671 Non-Turbo (2-Valve Head Type) engine is part of the iconic Detroit Diesel 71 Series — a legacy of two-stroke powerplants known for reliability, simplicity, and durability across marine, industrial, and power generation applications. Whether powering tugboats, cranes, or stationary equipment, these engines depend on a precise and efficient fresh water cooling system to maintain performance under demanding conditions.

Diesel Pro Power offers a complete line of Detroit Diesel 671 Non-Turbo cooling system components, including fresh water pumps, thermostats, hoses, gaskets, fittings, and repair kits, ensuring that your engine runs at optimal temperature and efficiency.

Overview of the Detroit Diesel 671 Cooling System

The 671 Non-Turbo engine uses a dual-circuit cooling design, separating fresh water (coolant) from raw water in marine configurations. The fresh water system circulates coolant through the engine block, cylinder head, and oil cooler, while the raw water (in marine use) passes through a heat exchanger to dissipate heat into seawater.

In land-based or industrial setups, the engine uses a radiator-based cooling system, circulating coolant through the radiator via the fresh water pump and thermostat. The efficiency of this system relies heavily on properly functioning components — particularly the fresh water pump, which keeps coolant flowing continuously through the engine passages.

Detroit Diesel 671 Fresh Water Pumps

Right-Hand Rotation Pump

The right-hand rotation water pump is designed for engines rotating clockwise when viewed from the flywheel end. This configuration is common in truck, industrial, and marine auxiliary applications. Built with robust impellers and heavy-duty bearings, this pump ensures reliable coolant circulation and steady engine temperature control.

• Application: Detroit Diesel 371, 471, and 671 engines

• Rotation: Right-hand (clockwise)

• Construction: Cast iron housing with precision-machined impeller

• Condition: New

• Use Case: Marine auxiliary engines, stationary power generators, and industrial drives

Left-Hand Rotation Pump

For engines rotating counterclockwise, the left-hand rotation pump delivers the same flow capacity and durability as the right-hand model. Designed for mirrored installations or twin-engine marine setups, this pump maintains balanced cooling between port and starboard engines.

• Application: Detroit Diesel 371, 471, 671

• Rotation: Left-hand (counterclockwise)

• Material: Heavy-duty cast iron

• Condition: New

• Usage: Ideal for twin marine propulsion systems or reverse-mounted installations

Both versions are designed to meet or exceed OEM Detroit Diesel specifications, ensuring direct compatibility and long service life.

Fresh Water Pump Repair Kits

Routine wear can degrade seals, bearings, and impellers within a pump. Diesel Pro Power’s Detroit Diesel 671 water pump repair kit allows quick and cost-effective servicing without full replacement.

Each kit includes:

• Pump shaft seals

• Bearings

• O-rings

• Gaskets

• Impeller hardware

This kit restores pump efficiency, reduces leaks, and prolongs the lifespan of your cooling system.

• Compatibility: Right-hand and left-hand pumps

• Condition: New

• Installation: Straightforward, with standard workshop tools

Properly rebuilding a pump every few years helps prevent overheating, cavitation, and internal corrosion.

Gaskets and Seals for the 671 Cooling System

Maintaining proper sealing is essential for preventing coolant leaks and preserving system pressure. Diesel Pro Power carries every gasket and O-ring required for your Detroit Diesel 671 cooling system.

Water Pump Gasket

This gasket fits between the water pump and engine block, ensuring a tight seal under high-pressure coolant circulation. Made from heat-resistant composite material, it prevents leakage and withstands temperature extremes.

Water Pump Cover Gasket

A vital seal for the rear pump cover or access plate. Over time, old gaskets can crack and allow coolant seepage. Replacing them ensures proper flow and avoids internal air leaks that could reduce pump efficiency.

Thermostat Housing and Thermostat Gaskets

• Thermostat Housing Gasket: Ensures a tight connection between the thermostat housing and cylinder head.

• Thermostat Gasket: Prevents coolant from bypassing the thermostat, ensuring accurate temperature regulation.

These gaskets are precision-cut for a perfect fit, preventing coolant leaks and maintaining consistent temperature control.

Detroit Diesel 671 Thermostat

The Detroit Diesel thermostat regulates engine temperature by controlling coolant flow between the block and radiator or heat exchanger. For the 671 Non-Turbo 2-valve configuration, the recommended thermostat opens at 173°F (78°C), ensuring optimal operating temperature for performance and efficiency.

• Opening Temperature: 173°F

• Application: 371, 471, 671 engines

• Function: Maintains proper engine operating range, prevents overcooling and overheating

Replacing an old thermostat improves fuel efficiency, reduces engine stress, and ensures consistent temperature management in varying ambient conditions.

Seals and Fittings for the 671 Fresh Water System

Proper sealing and secure connections are critical in any liquid-cooled engine. Diesel Pro Power offers OEM-grade O-rings, drain fittings, and manifold seals for the Detroit Diesel 671 cooling circuit.

O-Rings for Pump Outlets

High-temperature O-rings provide leak-free connections at the pump outlet and hose interfaces. These durable elastomer seals withstand long-term exposure to coolant, vibration, and temperature cycling.

Drain Fittings

Draincocks and fittings allow controlled coolant drainage during maintenance or storage. Available in both 3/8-inchand 1/4-inch configurations, they fit seamlessly into the Detroit 671 block or manifold, ensuring convenient fluid servicing.

Water Manifold to Oil Cooler Seals

These large-diameter seals (2.5" and 2.75") maintain a tight bond between the water manifold and the oil cooler housing. Worn or hardened seals can cause cross-contamination between oil and coolant — a costly issue easily prevented through timely replacement.

Radiator and Cooling Accessories

In industrial configurations, the Detroit Diesel 671 Non-Turbo uses a heavy-duty radiator for coolant heat dissipation.

Industrial Radiator

Designed specifically for 371, 471, and 671 engines, this radiator maintains consistent coolant temperature even under sustained heavy loads. Constructed from durable brass and copper cores, it ensures long-term corrosion resistance and efficient thermal transfer.

• Use: Industrial and stationary engines

• Features: High-capacity core, reinforced tanks, and precision-welded joints

• Benefit: Reliable cooling in hot or continuous-duty environments

Radiator Caps and Necks

The radiator system is complemented by correctly sized caps and necks to maintain pressure and coolant retention. The 7 PSI radiator cap ensures the proper pressure balance, increasing the coolant’s boiling point and improving efficiency.

• Small Neck: 1.63” ID – for compact radiator designs

• Large Neck: 2.17” ID – for high-volume radiator systems

Correct cap and neck selection maintains the system’s pressure integrity and prevents coolant loss under high temperatures.

Water Bypass Tube

The water bypass tube connects the thermostat housing to the water pump, enabling continuous circulation when the thermostat is closed. This feature ensures smooth warm-up and prevents localized hot spots.

• Application: 71 Series (371, 471, 671)

• Material: Corrosion-resistant steel or brass

• Function: Stabilizes engine temperature during warm-up and partial-load operation

Cooling System Maintenance Accessories

Radiator Cleaner

Deposits inside the radiator or heat exchanger can significantly reduce cooling efficiency. Diesel Pro Power’s radiator cleaner removes scale, rust, and sediment buildup safely and effectively. Recommended for both marine and land-based Detroit Diesel 671 engines.

Temperature Switch

A universal temperature switch fits Detroit Diesel, Cummins, and Caterpillar engines. This switch closes at 205°F, activating warning lights or alarms to protect against overheating. The standard 1/2” NPT thread allows for direct replacement on most Detroit 671 models.

Detroit Diesel Green Engine Paint

Restore your engine’s classic look with Detroit Diesel Green Paint — durable, heat-resistant, and true to the factory color. Ideal for touch-ups after component replacement or full restorations.

Silicone Coolant Hoses

The coolant hoses play a crucial role in connecting the pump, radiator, thermostat housing, and heat exchanger. Diesel Pro Power offers premium silicone hoses with exceptional heat resistance, flexibility, and longevity compared to standard rubber hoses.

Available Sizes (Inside Diameter)

• 3/4”

• 1”

• 1-3/4”

• 1-7/8”

• 2”

• 2-1/8”

• 2-1/4”

• 2-3/8”

• 2-1/2”

• 2-3/4”

• 3”

• 3-1/2”

• 4”

Each hose is sold by the foot for customizable installation lengths, ensuring a perfect fit for your Detroit Diesel 671 configuration.

Advantages of Silicone Hoses

• Superior heat and pressure resistance

• Longer lifespan than conventional hoses

• Resistant to coolant chemicals and oil exposure

• Smooth interior surfaces improve coolant flow

Hose Clamps and Fittings

Durable stainless-steel hose clamps ensure secure connections and leak prevention across all coolant lines. Diesel Pro Power stocks a complete range of clamps in various diameter ranges, providing compatibility for every hose size in the Detroit Diesel 671 cooling circuit.

Each clamp features:

• Corrosion-resistant construction

• Wide band for uniform pressure distribution

• Adjustable screw-tightening mechanism

These clamps are essential for maintaining coolant integrity and preventing air intrusion into the system — especially critical for older engines operating under vibration and thermal stress.

Mechanical and Electrical Temperature Gauges

For precise monitoring, Diesel Pro Power offers both mechanical and electrical gauges compatible with Detroit Diesel engines. Available in 12-volt and 24-volt versions, these gauges allow accurate temperature tracking, ensuring your cooling system performs efficiently.

• Mechanical gauges: Use direct coolant sensing for reliable readings without electrical input.

• Electrical gauges: Ideal for dashboards, control panels, and marine installations requiring remote readouts or alarms.

Proper instrumentation helps operators detect early signs of cooling system issues before damage occurs.

Maintaining the Detroit Diesel 671 Cooling System

Consistent maintenance is key to preserving engine health. Follow these general service recommendations:

1. Inspect the water pump annually for bearing noise, seal leaks, or reduced coolant circulation.

2. Replace thermostats every 2–3 years or whenever erratic temperature readings occur.

3. Flush the cooling system periodically using an approved radiator cleaner to prevent corrosion and scale buildup.

4. Replace hoses and clamps at the first sign of wear or cracking.

5. Monitor coolant pressure and temperature with calibrated gauges to ensure optimal performance.

Regular attention to these components helps extend the lifespan of your Detroit Diesel 671 Non-Turbo engine and minimizes costly downtime.

Why Buy Detroit Diesel 671 Non-Turbo Fresh Water Pump & Cooling System Parts from Diesel Pro Power

Choosing the right supplier is just as important as choosing the right component — especially when maintaining a classic workhorse like the Detroit Diesel 671 Non-Turbo (2-Valve Head Type) engine. At Diesel Pro Power, we understand that reliability and precision matter most when it comes to keeping your equipment running efficiently. That’s why thousands of customers worldwide depend on us for Detroit Diesel cooling system components that meet or exceed OEM standards.

Global Reputation for Excellence

With over 40,000 satisfied customers in more than 180 countries, Diesel Pro Power has built a global reputation for consistency, trust, and service. From commercial fleets to marine operators, industrial sites, and power generation facilities, our customers rely on us to deliver the right part the first time. Our commitment to quality extends beyond sales — it’s rooted in decades of experience supporting Detroit Diesel two-stroke engines around the world. Whether you operate a vessel in the Caribbean, a generator in the Arctic, or heavy equipment in South America, Diesel Pro Power ensures that your parts arrive promptly and perform flawlessly.

Premium Aftermarket Quality You Can Count On

Every component we sell — from fresh water pumps and repair kits to thermostats, gaskets, and hoses — is carefully inspected to ensure compliance with Detroit Diesel engineering standards. Our products are designed for long-term durability, providing the same precision fit and performance as OEM parts, often with modern material improvements. This means better corrosion resistance, longer seal life, and enhanced thermal stability in extreme temperature environments.
We know that even a small coolant leak can lead to significant downtime or engine failure, which is why Diesel Pro Power only supplies tested, dependable components trusted by professionals in marine, industrial, and commercial sectors.

Complete, Easy-to-Navigate Catalog

One of Diesel Pro Power’s core strengths is our fully organized online catalog, tailored specifically to Detroit Diesel engines. Each part is indexed by engine model, series, and system, allowing operators and technicians to locate compatible components quickly. For the Detroit Diesel 671 Non-Turbo engine, the cooling system section includes detailed listings for every item — pumps, repair kits, gaskets, seals, hoses, clamps, thermostats, radiators, and fittings. This streamlined organization eliminates guesswork and saves valuable time during maintenance or overhaul projects.

Fast, Reliable Worldwide Shipping

Downtime costs money — whether your engine powers a tugboat, industrial compressor, or backup generator. Diesel Pro Power is structured for speed, offering same-day order processing and fast international delivery to minimize operational interruptions. Our logistics network reaches major ports, marinas, and industrial hubs across the globe, ensuring that Detroit Diesel 671 owners receive their components quickly and securely. We also provide reliable tracking and professional packaging, so your water pump or cooling system parts arrive ready for immediate installation.

Expert Technical Support and Guidance

Technical expertise is what sets Diesel Pro Power apart. Our support team includes specialists with in-depth knowledge of Detroit Diesel two-stroke engines, including the 71 Series family. They assist customers in selecting the correct pump rotation (right-hand or left-hand), verifying thermostat temperature ratings, confirming hose diameters, and ensuring proper gasket and seal compatibility. Whether you’re restoring a vintage marine engine or maintaining an industrial power unit, Diesel Pro Power’s experts are available to guide you through each step — from product selection to troubleshooting your cooling circuit.

A Long-Term Partner in Engine Performance

When you choose Diesel Pro Power, you’re not just buying replacement parts — you’re investing in a long-term relationship with a trusted industry partner. We share your commitment to keeping classic Detroit Diesel engines alive and performing at their peak. Our mission is to support engine longevity through access to premium parts, technical insight, and a seamless purchasing experience.
Every Detroit Diesel 671 owner, mechanic, and fleet operator who works with us benefits from a combination of heritage expertise and modern efficiency. From your first order to ongoing maintenance years later, Diesel Pro Power remains your dedicated source for every cooling system component you’ll ever need.