Engine Water Pump

Cummins 4B Engine Parts – Fresh Water Pump and Cooling System Components

The Cummins 4B 3.9L engine is one of the most durable and efficient four-cylinder diesel engines in industrial and marine applications. Whether it's used for pumps, generators, or compact marine vessels, keeping the engine cool is essential for maximizing performance and engine life. At Diesel Pro Power, we offer a complete selection of Cummins 4B fresh water pump and cooling system parts, designed for fast shipping and long-term reliability.

Engine Water Pump for Cummins 4B 3.9L

Direct-Fit Fresh Water Pump Replacement

This engine-mounted centrifugal water pump is engineered for Cummins 4B 3.9L engines. It ensures proper coolant circulation through the engine block and cylinder head, preventing overheating during prolonged or high-load operation. This pump is a drop-in replacement and fits a wide range of Cummins CPL numbers, including but not limited to: 1975, 2122, 2292, 2893, 2686, 8039, 741, and 2243.

• Heavy-duty cast construction
  
  

• Pulley-driven design with OEM-spec fitment
  
  

• Includes gasket or O-ring seal depending on configuration
  
  

• Matches original equipment coolant flow rates and pressure
  
  

This pump supports both industrial-grade diesel engine applications and marine engines requiring raw water-to-freshwater heat exchanger configurations.

Thermostats for Cummins 4B Cooling Systems

Maintaining optimal engine temperature starts with the right thermostat. Cummins 4B thermostats are temperature-sensitive valves that open and close to regulate coolant flow between the engine block and the radiator or heat exchanger.

165°F Thermostat

Perfect for marine and cold-weather applications, the 165°F thermostat opens earlier to help prevent overheating when coolant flow needs to start sooner. Common in vessels and enclosed spaces with limited airflow.

• Ideal for marine cooling systems using heat exchangers
  
  

• Allows earlier coolant flow
  
  

• Reduces thermal load on engine components
  
  

180°F Thermostat

The 180°F thermostat maintains factory engine temperature for most industrial applications. It balances warm-up time with thermal efficiency.

• Standard temperature rating for industrial duty cycles
  
  

• Excellent for generator sets, pumps, and mobile equipment
  
  

• Compatible with Cummins 4B, 4BT, ISB, and QSB variants
  
  

Thermostat Gaskets and Seals

To complete any thermostat service job, you'll need proper sealing components. We supply OEM-quality gaskets and seals that provide a leak-free fit.

• Thermostat Housing Gasket – Seals the thermostat cover to the engine block
  
  

• Thermostat Seal – Forms a tight seal around the thermostat housing neck
  
  

• All seals are built to withstand prolonged heat and coolant exposure
  
  

Belt Tensioners and Fan Drive Components

Your Cummins 4B’s water pump relies on the belt drive system for consistent performance. We carry tensioners and fan belts designed specifically for the B-Series platform.

Belt Tensioners

We offer two compatible tensioners based on pulley type:

• Plain Pulley Tensioner – Ideal for standard belt systems with smooth pulleys
  
  

• Grooved Pulley Tensioner – Designed for serpentine systems with ribbed belts
  
  

Each tensioner keeps your belt at the correct tension to prevent slippage or premature wear.

Belts for Water Pump, Alternator, and Fan Drive

We stock a wide range of serpentine V-belts for Cummins 4B engine applications. These belts drive the water pump, alternator, and cooling fan from the crankshaft pulley.

Belt Features:

• Ribbed (8-rib) serpentine design
  
  

• Width: 1.125"
  
  

• Various lengths available: 53.50", 57.5", 59", 59.5", 60", 66.53", 66.92", 69", and more
  
  

Common Belt Uses:

• Water Pump Drive – Ensures continuous coolant circulation
  
  

• Alternator Drive – Powers charging system for battery and electrical components
  
  

• Fan Drive – Maintains airflow across radiator or heat exchanger
  
  

Our belts are compatible with multiple Cummins engine families, including 4B, 4BT, ISB 5.9, ISB 6.7, QSB 5.9, and QSB 6.7.

High-Temp Silicone Coolant Hoses

Durable silicone hoses are essential for coolant transfer between the water pump, thermostat housing, radiator, and other components. Our reinforced coolant hoses for the Cummins 4B engine are made from heat- and pressure-resistant silicone.

Available Inner Diameters:

• 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 and is rated for marine and industrial coolant systems. Perfect for applications requiring tight bends and minimal deformation under heat.

Hose Clamps for Cooling & Fuel Lines

Secure every hose connection with stainless steel clamps rated for high vibration and thermal cycles. We stock clamps in various sizes to accommodate all hose diameters used in the Cummins 4B engine cooling system.

Effective Diameter Ranges:

• From 9/16" up to 3.5"
  
  

• Compatible with both coolant and fuel hoses
  
  

• Easy-to-install worm gear design
  
  

All clamps are corrosion-resistant and tested for extended exposure to heat and fluid.

Supporting Cooling System Parts

Temperature Switch

We offer a compatible engine temperature switch for Cummins 4B applications. This sensor closes at 205°F and features 1/2" NPT threading for easy installation. It is essential for activating alarms or shutdown sequences in high-temp conditions.

Radiator Cleaner

Keep your coolant system running efficiently with a radiator cleaner designed for diesel engines. This product removes rust, scale, and mineral buildup from the heat exchanger and internal coolant passages.

• Compatible with Cummins and Detroit Diesel
  
  

• Safe for use with aluminum, brass, and copper cores
  
  

• Ship-ground within the USA and Canada
  
  

Why Choose Diesel Pro Power for Cummins 4B Cooling System Parts?

With over 40,000 satisfied customers worldwide, Diesel Pro Power is the trusted source for hard-to-find and reliable diesel engine parts. All products are in stock, competitively priced, and ready to ship fast. Our Cummins 4B parts are quality-tested to meet or exceed OEM performance—ensuring that your engine stays cool and runs strong.

Whether you're servicing an industrial genset, rebuilding a marine propulsion system, or restoring a legacy machine, we provide the cooling system parts you need to get the job done right the first time.