Cummins NH855 Engine Parts – Oil Pump & Lubrication System

The Cummins NH855 engine, part of Cummins’ proven heavy-duty series, is built for reliability and endurance in demanding marine and industrial applications. A properly functioning lubrication system is essential to keep this large displacement engine running smoothly, preventing wear, overheating, and premature failure of internal components.

Below, you’ll find a complete catalog of oil system components for the Cummins NH855, including oil pumps, oil coolers, thermostats, seals, filters, pressure switches, and related accessories. These parts are carefully designed to maintain proper oil circulation, regulate temperature, and protect your investment in one of Cummins’ most trusted engine platforms.

Oil Pump Assemblies for Cummins NH855

The oil pump is the heart of the NH855 lubrication system. It ensures that pressurized oil reaches the crankshaft, camshaft, bearings, pistons, and valve train. Without a properly functioning pump, engine damage can occur quickly.

Cummins NH855 Oil Pump Assembly
Designed specifically for both Small Cam and Big Cam I NH855 engines, this pump assembly provides the reliable oil pressure required under load. Engineered for durability, the gear-driven design ensures long service life and consistent performance in both marine and industrial environments.

Regular inspection of the oil pump is critical. Signs of pump wear include low oil pressure, excessive bearing wear, or noisy operation. Replacing the oil pump during major service intervals ensures continued protection of your NH855 engine.

Oil Coolers & Installation Kits

Oil coolers help maintain proper lubrication by controlling oil temperature. Overheated oil loses viscosity and its ability to protect engine components, which can lead to premature wear.

Cummins Oil Cooler Core
Heavy-duty tube bundle core measuring 6.5" x 4". This cooler is designed to dissipate heat efficiently, keeping oil within the recommended operating temperature range.
Oil Cooler Installation Kit for Cummins NH855
Complete installation hardware ensures a proper fit and seal when replacing or servicing the oil cooler.

Together, these components prevent overheating and maintain stable oil flow across varying load conditions.

Oil Filters & Filter Accessories

Clean oil is vital to the health of the NH855. Contaminants such as carbon deposits, dirt, and metal fragments can quickly damage bearings and moving parts if left unfiltered.

Spin-On Oil Filter
Compatible with both Cummins and Detroit Diesel engines, this spin-on filter provides efficient filtration and easy installation.
Oil Filter Removal Wrench
Adjustable removal tool suitable for Cummins, Detroit Diesel, and Caterpillar engines. Sized for filters ranging from 4-21/32" to 5-5/32", this wrench makes servicing easier in tight spaces.

Using quality filters and the right removal tools helps ensure smooth service intervals and long-term engine protection.

Thermostats & Oil Cooler Temperature Regulation

Temperature regulation is essential to balancing oil flow and cooling.

Cummins Thermostat for Oil Cooler
Designed for Cummins NH855, NT855, and N14 engines. Calibrated to open at 225°F, ensuring oil is circulated through the cooler when temperatures rise beyond optimal levels.

This thermostat plays a critical role in preventing overheating, reducing thermal stress, and maintaining oil viscosity for reliable lubrication.

Seals, Gaskets & Zincs

Preventing leaks and corrosion is a key part of maintaining your NH855 oil system.

Cummins Oil Seal for Fan Hub
Protects the fan hub from oil leaks, ensuring lubrication stays contained within the system. Compatible with NH855, NT855, and N14 engines.
Cummins Gasket for Bypass Valve
A precision washer seal designed for secure installation, reducing the risk of leaks at bypass points.
Zinc Anodes for Oil & Fuel Coolers
Designed for Cummins marine engines, these zinc inserts protect oil and fuel coolers from galvanic corrosion. With a brass plug and replaceable zinc insert, they are a simple but effective way to extend the life of your cooling and lubrication components.

Oil Pressure Switches

Oil pressure monitoring is essential for engine safety. Pressure switches detect abnormal conditions and can trigger alarms or shutdown systems to protect against damage.

Fuel & Oil Pressure Switch – 5 PSI
Activates at low pressure to provide early warnings.
Fuel & Oil Pressure Switch – 10 PSI
Common for mid-range pressure applications, ensuring adequate lubrication.
Fuel & Oil Pressure Switch – 20 PSI
Helps monitor oil system performance in higher-pressure operating conditions.
Fuel & Oil Pressure Switch – 27 PSI
Provides added protection in heavy-duty applications, ensuring lubrication is never compromised.

All switches are threaded with 1/8" NPT fittings for secure installation and reliable electrical connection to monitoring systems.

Oil Pressure & Temperature Gauges

Monitoring oil conditions in real time helps prevent catastrophic engine failure.

Mechanical Gauges
Direct-read gauges provide immediate, reliable oil pressure and temperature readings.
Mechanical Gauges with Alarms
Enhanced safety with built-in alarms for low or high readings.
Electrical Gauges (12 Volt & 24 Volt options)
Designed for both standard and heavy-duty applications, providing easy integration into marine and industrial panels.

Proper instrumentation ensures operators have continuous visibility into the NH855’s lubrication system performance.

Why Choose Diesel Pro Power for Cummins NH855 Oil System Parts?

With over 40,000 satisfied customers worldwide, Diesel Pro Power has become the trusted source for Cummins NH855 parts. Every component we carry—from oil pumps to gauges—is designed for reliability, durability, and ease of installation.

When you shop with Diesel Pro Power, you benefit from:

Fast worldwide shipping.
Easy-to-navigate catalog organized by engine model.
Expert customer support for technical questions.
High-quality aftermarket and OEM-compatible components.

Cummins Oil Cooler Core

Frequently added by mechanics