Cummins ISB 5.9 Fresh Water Pump & Cooling System Components

The Cummins ISB 5.9 engine is renowned for its reliability, durability, and versatility across a wide range of marine, industrial, and stationary applications. At the core of the ISB 5.9's thermal control system is the fresh water pump—a vital component that maintains engine temperature by circulating coolant through the engine block and cooling system. This detailed catalog covers all major parts that support the Cummins ISB 5.9 cooling circuit, from water pumps to belts, hoses, thermostats, and sensors.

Engine Water Pump for Cummins ISB 5.9

The Cummins ISB 5.9 fresh water pump is designed to maintain a continuous flow of coolant throughout the engine under high-load conditions. Diesel Pro Power supplies a reliable water pump compatible with dozens of CPL configurations, including but not limited to CPL#s 1975, 2122, 8266, 8306, 2893, 2063, 2292, 1889, 2071, 1948, 8444, 8236, 2891, 1288, 2372, 2243, 599, 2530, 714, 1962, 1519, 8208, 2014, 1523, 8267, 2373, 1524, 8217, 2686, 8304, 2208, 8239, 2377, 1525, 1522, 8039, 2109, 2264, 2246, 2302, 2351, 1967, 1268, 741, 591, 2486, 721, 594, and 1965.

Water Pump Features:

• Cast aluminum or iron housing

• High-efficiency impeller

• Precision-sealed bearing assembly

• Factory-calibrated flow performance

Each water pump is a direct-fit replacement, ensuring easy installation and long-term operation under high-temperature and high-vibration conditions.

Water Pump Seal Ring

When replacing the water pump, it's critical to also replace the seal ring. This component provides a tight seal between the pump and engine block, preventing coolant leakage and maintaining internal system pressure.

Features:

• Resistant to heat and coolant additives

• Precisely machined for a perfect fit

• Helps eliminate air leaks that could cause cavitation

Proper sealing ensures efficient cooling and prolongs the life of your water pump and engine.

Cummins ISB 5.9 Thermostats

Thermostats are crucial for maintaining consistent engine temperature by regulating coolant flow based on temperature.

165°F Thermostat:

• Opens earlier to improve cooling response

• Best suited for marine and generator use in cooler climates

180°F Thermostat:

• Standard option for most ISB 5.9 installations

• Maintains fuel efficiency and engine longevity

Thermostat Seal:

• Protects against leaks between the housing and block

• Maintains seal integrity at high temperatures and pressures

Replacing the thermostat during water pump service ensures the entire cooling system functions optimally.

Belt Tensioners for ISB 5.9 Engines

Tensioners keep drive belts tight and properly aligned. Diesel Pro Power offers two models:

Plain Pulley Style Tensioner:

• Easy to install and service

• Supports a wide range of B-series engines

Grooved Pulley Style Tensioner:

• Enhanced belt grip

• Compatible with ISB, QSB, 6C, and 6CT models

Replacing the tensioner with your water pump helps avoid premature belt wear or failure.

Serpentine Belts for Water Pump, Alternator, and Fan

Drive belts power the fresh water pump and other accessories. Available belts include:

• 53.50"

• 59.50"

• 66.53"

• 66.92"

• 69.0"

Features:

• 8-rib serpentine design

• High friction surface for reduced slippage

• Reinforced construction to withstand extreme heat

Belt replacement is essential during cooling system overhauls to ensure consistent pump operation.

Radiator Cleaner and System Flush Additive

A thorough flush of the coolant system removes deposits and corrosion before installing a new pump or thermostat.

Radiator Cleaner Benefits:

• Dissolves scale and debris

• Enhances coolant flow

• Helps maintain lower engine temperatures

Compatible with marine and land-based Cummins ISB 5.9 installations.

Coolant Temperature Switch

The coolant temperature switch activates an alert or fan circuit when coolant exceeds 205°F. It features:

• 1/2" NPT thread

• Fast response design

• Reliable performance in marine, generator, and industrial engines

Ideal for safety shutdown systems or auxiliary fan control in critical applications.

Silicone Coolant Hoses

Diesel Pro Power offers a complete selection of premium silicone hoses that outperform traditional rubber alternatives.

Available Inner Diameters:

• 3/4" to 4"

Key Advantages:

• Withstands high engine temperatures

• Superior resistance to chemical breakdown

• Long-term durability in saltwater environments

Perfect for replacing OEM hoses or custom routing around auxiliary components.

Coolant Hose Clamps

Heavy-duty clamps ensure leak-free connections at every hose joint. Options include:

• Standard worm-gear clamps from 9/16" to 3.5"

• Stainless steel construction

• High-torque fastening for high-pressure systems

Clamps should be replaced during pump, hose, or thermostat servicing.

Gauges for Temperature Monitoring

Keep your ISB 5.9 engine safe with real-time monitoring:

Gauge Types:

• Mechanical with or without alarm

• Electric 12V and 24V options

Monitoring systems let you detect problems early and help prevent severe overheating.

Installation Tips for Water Pump & Cooling System Service

1. Drain and Flush: Use radiator cleaner and flush to prepare the system.

2. Inspect All Seals: Replace thermostat seals and water pump O-rings.

3. Replace Belts and Tensioners: Prevent belt-related failures.

4. Use Silicone Hoses and New Clamps: Ensure longevity and proper sealing.

5. Test Coolant Temp Sensor and Switches: Confirm accuracy after reassembly.

6. Refill and Bleed Air: Refill with recommended coolant and bleed system thoroughly.

7. Monitor System: Use gauges or sensors to ensure correct temperatures under load.

Applications That Rely on the ISB 5.9 Cooling System

The Cummins ISB 5.9 powers a wide range of equipment:

• Marine propulsion systems

• Mobile generators

• Agricultural tractors and irrigation units

• Construction machinery

• Stationary pump systems

Every application demands precise thermal control. A properly maintained cooling system ensures dependable service in all of them.

Why Diesel Pro Power?

With over 40,000 satisfied customers worldwide, Diesel Pro Power is the trusted source for Cummins engine parts. We offer:

• Expert customer service

• Parts organized by engine model

• Fast worldwide shipping

• Quality parts tested for reliability

Our ISB 5.9 cooling system catalog provides everything you need to keep your engine running cool and efficient.