Cummins ISB 5.9L Camshaft & Valve Train Parts Catalog

The camshaft and valve train in the Cummins ISB 5.9L engine are at the core of its performance, determining valve timing, fuel-air mixture delivery, and exhaust flow. In marine and industrial applications, where engines often operate under heavy load for extended periods, keeping these components in top condition is critical for reliability and efficiency.

At Diesel Pro Power, we provide premium camshaft components, bushings, and valve lifters for Cummins ISB 5.9L engines, as well as compatible ISB 4.5, QSB 4.5, QSB 5.9, and QSB 6.7 models. With over 40,000+ satisfied customers worldwide, our catalog is built to serve professionals who demand more than just parts — they need proven durability and expert support.

Engine Specifications & Applications

The Cummins ISB 5.9L is a 6-cylinder, in-line, turbocharged diesel engine widely used in both marine propulsion and industrial power generation. Known for its balance of fuel economy, torque output, and long service life, it has become a go-to choice for vessels, heavy-duty equipment, and stationary machinery.

Key specifications include:

• Displacement: 5.9 liters

• Configuration: Inline-6

• Aspiration: Turbocharged, with some models using intercooling

• Fuel System: High-pressure common rail or earlier mechanical systems (depending on build year)

• Bore & Stroke: 102 mm x 120 mm (4.02 in x 4.72 in)

• Applications: Marine main propulsion, auxiliary power units, gensets, industrial pumps, cranes, and construction machinery

In all of these roles, the camshaft assembly and related components must function flawlessly to deliver consistent timing, efficiency, and durability.

Understanding the Camshaft’s Role in the Cummins ISB 5.9L

The camshaft is responsible for controlling the precise opening and closing of the engine’s intake and exhaust valves. It does so by converting rotational motion from the crankshaft into linear movement that operates the valves via lifters, pushrods, and rocker arms.

In a Cummins ISB 5.9L, accurate valve timing is vital for:

• Achieving maximum torque across the RPM range

• Ensuring efficient combustion

• Minimizing fuel consumption

• Controlling exhaust emissions

• Protecting the turbocharger from excessive exhaust backpressure

A worn camshaft, or damage to supporting components such as lifters and bushings, can lead to severe performance losses and even complete engine failure.

Camshaft Bushings for Cummins ISB 5.9L

Function and Importance

Camshaft bushings act as precision bearings that support the camshaft journals within the engine block. These bushings must endure constant rotation under high pressure while maintaining oil clearance that prevents metal-to-metal contact.

When bushings wear out, common issues include:

• Camshaft misalignment

• Increased friction and heat

• Accelerated cam lobe wear

• Loss of valve timing accuracy

Signs of Worn Camshaft Bushings

• Metallic knocking from the valve train

• Low oil pressure due to excessive clearance

• Irregular valve timing, resulting in rough idle or reduced power

• Metal particles in the oil filter during routine service

Diesel Pro Power Camshaft Bushings – Key Features

• High-grade alloy construction for maximum strength and wear resistance

• Precision-machined for perfect fit in Cummins ISB and QSB engines

• Designed for stable lubrication and reduced friction

• Fully compatible with ISB 4.5, ISB 5.9, QSB 4.5, QSB 5.9, and QSB 6.7

Replacement Recommendation: Always replace camshaft bushings during major overhauls or when installing a new camshaft. Doing so prevents premature wear and ensures smooth operation.

Valve Lifters (Tappets) for Cummins ISB 5.9L

Role in the Valve Train

Valve lifters, or tappets, sit between the camshaft lobes and the pushrods, transferring the cam’s rotational movement into the vertical motion needed to open and close valves. In the ISB 5.9L, proper lifter operation is essential for maintaining correct valve lift and duration.

Types of Valve Lifters Offered

We supply two types of lifters for ISB and QSB engines, tailored to build year:

Pre-2003 ISB & QSB Valve Lifters

• Designed for older cam profiles and valve train geometry

• Hardened contact surfaces to resist scuffing and wear

• Maintains OEM lift and duration specifications

2003 and Later ISB & QSB Valve Lifters

• Modified design to match updated camshaft profiles in electronically controlled engines

• Improved surface finish for reduced break-in wear

• Supports higher injection pressures and tighter emission standards

Symptoms of Failing Valve Lifters

• Ticking noise from the valve cover area

• Loss of engine power or misfires

• Uneven valve operation detected during adjustment

• Metal debris in oil from lifter face wear

Maintenance Tip: Always install lifters in matched sets and pair them with a camshaft in good condition to prevent rapid wear.

Common Causes of Camshaft & Lifter Failure

Camshaft and lifter damage can be caused by several factors:

1. Poor Lubrication: Low oil pressure or oil contamination accelerates wear.

2. Improper Break-In: Skipping the break-in procedure for a new camshaft can lead to early lobe failure.

3. Valve Train Misalignment: Bent pushrods, worn rocker arms, or improper assembly can cause uneven loading.

4. Overloading: Prolonged high-load operation without proper cooling or lubrication.

5. Foreign Particles: Dirt or metal fragments circulating in oil can scratch or pit surfaces.

Best Practices for Installation

When installing camshaft and valve train components in a Cummins ISB 5.9L:

• Use Assembly Lube: Always coat lobes, journals, and lifter faces before initial startup.

• Verify Oil Flow: Ensure passages are clear before assembly.

• Follow Torque Specs: Over- or under-tightening can cause distortion or misalignment.

• Check Endplay: Excessive endplay can lead to timing irregularities and premature wear.

• Align Timing Marks Precisely: Incorrect timing can cause catastrophic piston-to-valve contact.

Camshaft and Valve Train Maintenance Schedule

For marine and industrial applications, preventive maintenance is essential:

• Every 500 hours: Inspect valve lash and adjust if needed.

• Every 1,000 hours: Check oil for contamination and inspect valve train noise.

• At Overhaul Intervals: Replace camshaft bushings and inspect all lobes for wear.

Marine & Industrial Considerations

In marine engines, camshaft wear can be accelerated by:

• Continuous high-load operation

• Saltwater corrosion if ventilation is inadequate

• Extended idle periods leading to oil film breakdown

In industrial engines, issues often arise from:

• Dust ingestion in off-highway environments

• Heat cycling in stationary generators

• Vibration in pump and compressor drives

Selecting high-quality camshaft components designed for heavy-duty service mitigates these risks.

Why Choose Diesel Pro Power

• Global Reach: We ship worldwide with fast, reliable service.

• Proven Quality: Components tested to meet or exceed OEM standards.

• Expert Guidance: Our team can advise on installation and maintenance.

• Stock Availability: Ready-to-ship parts for ISB 5.9L and related engines.