Cummins QSB 4.5 Parts - Cylinder Head Section

Cylinder Heads & Related Components for Cummins QSB 4.5

The Cummins QSB 4.5 engine, widely recognized for its durability in industrial and marine applications, relies heavily on a high-quality cylinder head to maintain compression, manage air and fuel flow, and support efficient engine performance. At Diesel Pro Power, we offer a comprehensive catalog of cylinder heads and related top-end components built to meet or exceed OEM specifications.

Whether you're performing a top-end rebuild, replacing a failed head, or servicing related components such as valves, springs, or gasket sets, our inventory provides everything needed for long-lasting performance and reliable operation in QSB 4.5 engines.

New Cylinder Heads for Cummins QSB 4.5 Engines

Fully Assembled Cylinder Heads (With Valves)

We stock fully assembled cylinder heads for Cummins QSB 4.5 engines, complete with intake and exhaust valves installed. These heads are machined and ready for bolt-on installation, saving valuable time during overhaul or engine replacement procedures. Designed for heavy-duty use in marine and industrial environments, our heads feature robust castings and improved coolant flow for optimal heat dissipation.

Two versions are available:

• A variant with a female oil filter connection and no coolant drain plug.

• A version with the same oil filter connection type but equipped with a coolant drain plug for easier fluid service.

Both versions are pressure-tested and validated to meet high-performance tolerances.

Intake & Exhaust Valves for Cummins QSB 4.5

Proper air and exhaust flow is essential to engine efficiency, fuel economy, and emissions compliance. We supply intake and exhaust valves designed to match Cummins QSB 4.5 factory profiles and metallurgy. Each valve is precision-ground and heat-treated to resist wear, corrosion, and warping under high-temperature conditions.

Key Features:

• One intake and one exhaust valve per cylinder

• Valve stem surface hardened for longevity

• Designed to interface with OEM guides and seals

• Compatible with ISB/QSB 4.5, 5.9, and 6.7 engines

Whether you're replacing individual valves due to seat wear or performing a complete cylinder head rebuild, our intake and exhaust valves deliver the reliability needed for long-duty cycles.

Valve Seats, Inserts, and Valve Seals

Valve Seat Inserts

Over time, valve seats may erode or become pitted, especially in engines operating in harsh marine environments. We offer hardened valve seat inserts for both intake and exhaust ports that restore sealing integrity and combustion efficiency. These inserts are compatible with QSB 4.5 cylinder heads and machined for precise installation.

Valve Stem Seals

Valve stem seals play a vital role in controlling oil flow along the valve stem, preventing excess oil consumption and carbon buildup in the combustion chamber. Our valve stem seals for QSB 4.5 applications are built with high-heat rubber compounds and metal reinforcement for long-term sealing and oil control.

Valve seal failure is one of the most common causes of smoking, especially during cold starts. Replacing them during a top-end refresh can greatly reduce oil burn and improve emissions compliance.

Valve Springs & Keepers for QSB 4.5

Each QSB 4.5 valve is supported by a high-tension coil spring that helps control valve motion and seating accuracy. Our valve springs are made from chrome-silicon alloys, designed to maintain pressure under repeated high-RPM and high-heat conditions. These springs resist fatigue and valve float, making them ideal for heavy-duty marine or off-road applications.

We also provide valve keepers (locks) that secure the valve springs in position. Our keepers are compatible with OEM spring retainers and are precision-machined for a secure, vibration-resistant fit.

Cylinder Head Bolts for Cummins QSB 4.5

Proper head bolt torque and uniform clamping force are critical to preventing head gasket failure. We offer two types of cylinder head bolts commonly used on Cummins QSB engines:

• 70mm bolts – Typically used in smaller displacement Cummins B-series heads

• 131mm bolts – For deeper block designs with greater clamping depth

All head bolts are high-strength, torque-to-yield fasteners with rolled threads and hardened hex heads. For best results, head bolts should not be reused and should always be installed using the proper torque pattern and specifications.

Valve Cover Gasket for QSB 4.5

Our valve cover gaskets are made from molded rubber or silicone-based materials to ensure a tight seal against oil leaks. These gaskets are designed specifically for QSB 4.5 engines and are resistant to oil, heat, and pressure deformation.

Replacing the valve cover gasket is a best practice when reinstalling or inspecting the cylinder head, especially if you're also replacing the rocker assembly or injectors.

Cylinder Head Gasket Set (Upper Gasket Kit)

We supply upper gasket kits that include all necessary gaskets and seals required when servicing the top end of the engine. These kits typically contain:

• Cylinder head gasket

• Valve cover gasket

• Intake and exhaust manifold gaskets

• Injector O-rings

• Valve stem seals

• Miscellaneous seals and washers

Choosing a high-quality upper gasket set ensures consistent sealing across all critical joints and reduces the likelihood of coolant or oil leaks post-repair.

Common Cylinder Head Issues in Cummins QSB 4.5 Engines

1. Cracked Cylinder Head

Often caused by overheating, cracks in the cylinder head can lead to coolant intrusion, misfires, and combustion loss. Replacing the head is the only long-term solution for restoring compression and preventing cross-contamination.

2. Burnt Valves

Burnt valves occur due to improper seating, poor timing, or extreme exhaust temperatures. This can reduce power and increase emissions. Replacing damaged valves or the entire head (if erosion is severe) is necessary.

3. Oil or Coolant Leaks

Worn valve seals, damaged gaskets, or improperly torqued head bolts can lead to oil seepage or coolant leaks. These are easily addressed with new gasket sets and hardware.

4. Valve Seat Recession

Common in engines exposed to poor fuel or high-duty cycles, this issue results in valve misalignment and poor sealing. Installing new seat inserts restores functionality and prevents valve failure.

Benefits of Replacing a Complete Cylinder Head

Replacing the entire cylinder head assembly—rather than rebuilding—has several advantages:

• Reduced labor time (no machining or cleaning needed)

• Eliminates guesswork from diagnosing microscopic cracks

• Brand-new valves and guides pre-installed

• Peace of mind with zero-hour rebuild baseline

Our heads come ready to install, offering a turn-key solution for shops and fleet operators alike.

Compatible Applications for Cummins QSB 4.5 Cylinder Heads

The Cummins QSB 4.5 engine is used in a wide range of industries, and our cylinder heads are engineered to support:

• Marine auxiliary and propulsion engines

• Agricultural tractors and combines

• Mining equipment and loaders

• Industrial generators

• Forestry equipment

• Construction machinery (excavators, rollers, etc.)

Whether your QSB 4.5 engine powers a marine vessel, generator, or mobile industrial machine, our cylinder heads are trusted in hundreds of applications worldwide.

Installation Best Practices

1. Clean all mating surfaces: Ensure no debris or warping exists on the cylinder block deck.

2. Inspect dowel pins and alignment guides: Misalignment can result in gasket blowout or improper sealing.

3. Use new head bolts: Always replace head bolts with new ones; torque-to-yield bolts cannot be reused.

4. Apply correct torque sequence: Refer to Cummins’ published bolt pattern and torque specs to prevent head warping.

5. Inspect push rods and rocker assembly: Replace worn components and verify valve lash after reassembly.

Why Choose Diesel Pro Power?

With over 40,000 satisfied customers and decades of experience in diesel engine parts, Diesel Pro Power is a leading supplier of Cummins QSB 4.5 components. Our products are trusted by marine engineers, industrial service centers, and heavy-duty diesel shops worldwide.

What sets us apart:

• Expert technical support for Cummins engine families

• Fast worldwide shipping

• In-stock inventory of new and remanufactured components

• Bilingual customer service in English and Spanish

• Guaranteed quality on every part sold