Blog
Feedback
Refer a Friend

Cummins QSB 5.9 Parts - Cylinder Head Section

Loading...

Cylinder Heads & Related Components for Cummins QSB 5.9 Engines

The Cummins QSB 5.9 is a workhorse in the diesel engine industry, widely used in marine propulsion systems, power generation, agricultural equipment, and heavy-duty industrial machinery. At Diesel Pro Power, we provide everything you need to perform a top-end overhaul or cylinder head service on this robust engine platform. Whether you're servicing a single marine generator or an entire fleet of equipment, our QSB 5.9 cylinder head components are stocked, ready to ship, and built to OEM-level standards.

Complete Cylinder Head Assemblies for QSB 5.9

We offer brand-new Cummins QSB 5.9 cylinder heads for marine applications, fully assembled with valves and valve springs installed. These heads are ready to bolt on out of the box and are engineered for heavy-duty reliability in continuous operation environments.

Key Features:

  • Brand new—never remanufactured

  • Fully assembled with valves and springs

  • Machined for direct fit on QSB 5.9 and ISB 5.9 engines

  • Designed to withstand marine thermal and corrosion conditions

When you replace your head with a new, fully built unit, you eliminate the guesswork of rebuilding worn castings and avoid unexpected failures from cracked combustion chambers or eroded valve seats.

Intake & Exhaust Valves

Maintaining proper airflow and exhaust scavenging is essential to the performance and emissions compliance of the QSB 5.9 engine. Diesel Pro Power stocks both intake and exhaust valves, along with optional kits that include stem seals and keepers.

Intake Valves

  • Constructed for high-heat resistance and clean combustion

  • Suitable for ISB and QSB 5.9 engines

  • Ensures maximum airflow efficiency into combustion chambers

Exhaust Valves

  • Built to endure high temperatures from turbocharged exhaust flow

  • Include valve keepers to simplify installation

  • Also available in complete kits with stem seals for full rebuilds

Replacing old or worn valves helps restore compression, improve idle quality, reduce oil consumption, and prevent valve breakage under heavy loads.

Valve Seals, Inserts & Valve Guides

Over time, valve seals and valve seats wear down from heat and fuel contamination, leading to poor sealing and higher oil consumption. Diesel Pro Power carries every component necessary for a thorough valve job.

Valve Seals:

  • Separate versions for intake and exhaust valves

  • Prevent oil from leaking into the cylinder through the valve stem

  • Maintain clean combustion and extend engine life

Valve Inserts (Seats):

  • Press-fit hardened rings provide reliable valve sealing

  • Intake and exhaust versions in stock

  • Protect the head from wear in high-duty applications

Valve Guides:

  • Maintain proper valve alignment and reduce stem wear

  • Critical for consistent valve timing and smooth engine operation

These parts are must-haves for any top-end refresh and help ensure long-term sealing integrity inside the cylinder head.

Cylinder Head Bolts

Cylinder head bolts are torque-to-yield fasteners and must be replaced each time the head is removed. Using old bolts can compromise sealing pressure and lead to gasket failure.

We Stock Two Common Sizes:

Always use new head bolts during installation and follow Cummins’ torque sequence and angle specifications for best results.

Upper Gasket Set for QSB 5.9

Our upper gasket set for the Cummins QSB 5.9 is a comprehensive sealing solution designed specifically for top-end rebuilds and cylinder head replacement. Each kit includes:

  • Head gasket

  • Valve cover gasket

  • Intake and exhaust manifold gaskets

  • Injector and valve stem seals

  • Thermostat housing and miscellaneous upper engine gaskets

Whether you’re reassembling a marine auxiliary engine or refreshing an industrial machine, this gasket set ensures you won’t miss any seals critical to a leak-free engine.

Valve Cover Gasket

Although often overlooked, the valve cover gasket plays an essential role in keeping the engine sealed from oil leaks and contamination. Our gasket for the ISB and QSB 6.7 engines also fits the 5.9L versions and is constructed to OEM-quality standards.

Features:

  • Rubber-reinforced for long life

  • Designed to handle high crankcase pressures

  • Ensures a tight seal between the valve cover and cylinder head

Replace this gasket whenever the valve cover is removed during inspection or service to avoid oil leaks and contamination.

Valve Springs

Valve springs are critical for ensuring valves close completely and maintain proper contact with camshaft followers. Fatigued springs can lead to valve float, misfires, or even piston-valve interference in extreme cases.

Details:

  • OEM-matched for spring pressure and coil count

  • Compatible across multiple Cummins models including 4BT, 6BT, ISB, and QSB

  • Should be inspected or replaced during any head service

Springs are often reused too long. Avoid performance issues by replacing them when rebuilding a head.

Valve Inserts for QSB 5.9

Valve seat inserts provide the hardened interface where the valve contacts the cylinder head. These inserts must endure thousands of high-pressure closures per minute under extreme heat.

Available Inserts:

These parts are crucial when machining used heads and help ensure valves maintain proper sealing and heat dissipation throughout engine life.

Temperature Switch (Multi-Brand Use)

While not exclusive to the QSB 5.9, Diesel Pro Power also carries temperature switches that serve multiple engine types, including Cummins, Detroit Diesel, and Caterpillar.

Specifications:

  • Activates at 205°F

  • 1/2" NPT thread for universal fitment

  • Commonly used in marine engine panels or overheat alert systems

Installing or replacing this switch during a rebuild helps safeguard your investment from thermal damage.

Why Choose Diesel Pro Power for Your Cummins QSB 5.9 Cylinder Head Components?

Diesel Pro Power has been the trusted source for premium diesel engine parts for over two decades. With over 40,000 satisfied customers globally, we’ve built a reputation for delivering reliable parts, fast.

What We Offer:

  • In-stock cylinder heads with valves for QSB 5.9 marine applications

  • Full line of head bolts, springs, valves, seals, and gasket sets

  • Worldwide shipping with same-day fulfillment on most orders

  • Expert support to ensure the right fit for your engine configuration

We don’t just sell parts—we support them. From installation guidance to torque spec references, we help ensure your engine runs right the first time.

Where Is the QSB 5.9 Cylinder Head Used?

The QSB 5.9 is found in a range of commercial and industrial engines across multiple industries. Common applications include:

  • Marine propulsion and auxiliary generators

  • Agricultural tractors, sprayers, and balers

  • Construction equipment like loaders and backhoes

  • Stationary power units for pumps, compressors, and gen-sets

In all these environments, cylinder head performance is critical to engine power, efficiency, and reliability.

 

+
URL Copied Send Quote