Cummins 4B Engine Parts - Cylinder Head Section

Cylinder Heads & Related Components for Cummins 4B Engine

Diesel Pro Power offers a complete range of cylinder head components for the Cummins 4B engine, designed to restore or enhance performance in marine and industrial applications. Whether you're rebuilding a worn-out head or replacing a cracked casting, our inventory covers all critical components to keep your 4B 3.9 engine operating with optimal power and efficiency.

Complete Cylinder Heads for Cummins 4B

We carry brand-new cylinder heads for the Cummins 4B 3.9 engine, assembled with valves and springs and ready for installation. These cylinder heads are engineered to meet original equipment specifications and are offered with either 7mm or 9mm injector tubes, depending on your engine’s injector configuration.

Each head is built from high-strength cast iron, precision-machined to ensure flatness, and inspected for structural integrity. The valve seats are hardened to withstand extreme heat and resist recession, while the valve guides and springs are pre-installed to simplify installation. These ready-to-bolt-on heads are ideal for mechanics and fleet managers looking to minimize downtime.

Whether you're working on a 4B naturally aspirated model or a turbocharged 4BT variant, Diesel Pro Power ensures the correct head configuration is available for your engine’s injector type and performance needs.

Intake and Exhaust Valves

High-quality intake and exhaust valves are essential for maintaining proper airflow and combustion in your Cummins 4B engine. Each intake valve is engineered for precision sealing, smooth airflow, and resistance to heat and corrosion. Similarly, our exhaust valves are designed to handle extreme exhaust gas temperatures without warping or pitting over time.

We supply one valve per cylinder, ensuring exact replacements that restore full compression and efficiency. All valves are compatible with factory valve springs, retainers, and guides used in the 4B and 4BT engines.

Valve Rotators

Valve rotators are small but critical components that enhance valve life and ensure even seat wear. On the Cummins 4B exhaust side, they reduce heat buildup by slowly rotating the valve during operation. This minimizes hot spots, helps prevent valve burning, and contributes to more stable performance over extended periods.

Our valve rotators are manufactured with durable materials designed to handle thousands of cycles and are engineered for precise fitment in the Cummins 4B’s cylinder head design.

Cylinder Head Bolts

A successful cylinder head installation on a 4B engine depends heavily on using the correct head bolts with proper torque sequences. We offer head bolts in both 70mm and 120mm lengths, matching Cummins factory specs. These bolts are engineered to provide proper clamping force without stretching or failing under thermal cycling.

It’s crucial to replace head bolts during cylinder head service, as reusing old bolts can lead to uneven torque distribution and eventual gasket failure. Our bolt sets are designed to handle the stress of diesel combustion and high compression ratios seen in the 4B engine family.

Head Gaskets and Upper Gasket Sets

The head gasket is one of the most critical sealing components in your Cummins 4B engine. We supply standard-size head gaskets and complete upper gasket sets that include all the necessary seals for cylinder head installation—valve cover gaskets, intake and exhaust manifold gaskets, injector tube seals, and more.

Standard and oversized gasket options are available to accommodate resurfaced cylinder heads. These gaskets are built with multi-layered construction and high-quality materials to withstand high combustion pressures and coolant temperatures.

Proper gasket sealing ensures no coolant or combustion gas leaks, maintaining engine performance and preventing costly breakdowns.

Valve Springs: Intake and Exhaust

Valve springs keep the valves seated tightly against their seats while controlling the opening and closing action during the engine’s cycle. Diesel Pro Power provides springs designed specifically for the Cummins 4B’s intake and exhaust valves.

The intake springs are precision-wound to maintain seating force without premature fatigue. Exhaust springs are designed for higher temperature resistance, critical in turbocharged applications where exhaust temperatures are elevated.

Replacing valve springs during a head rebuild is a best practice to prevent valve float or loss of compression under load.

Valve Inserts: Intake and Exhaust

Valve seat inserts, sometimes called valve inserts, are installed in the cylinder head to provide a hard-wearing surface for the valve to seal against. Over time, valve seats can become pitted, cracked, or recessed due to high heat and poor lubrication.

Diesel Pro Power supplies both intake and exhaust valve inserts for the Cummins 4B and 4BT engine family. These are precision-ground and constructed from hardened alloys to resist wear and extend valve life.

Installing new inserts is often necessary during head machining, particularly on engines that have experienced valve seat erosion or overheating.

Valve Guides: Intake and Exhaust

Valve guides provide lateral support to the valve stem, ensuring proper alignment and controlling oil flow. We carry intake and exhaust valve guides for the Cummins 4B, compatible with both naturally aspirated and turbocharged variants.

Our guides are built to exact dimensions and made from wear-resistant materials, allowing for long service life even in high-temperature environments. If you’re rebuilding your cylinder head or experiencing valve instability, replacing worn guides is a must.

Valve Guide Seals

Valve guide seals prevent excess oil from leaking into the combustion chamber via the valve stem. Our seals are compatible with both intake and exhaust valves for the 4B 3.9 engine, designed to withstand extreme temperatures and oil exposure.

Worn or hardened valve seals can lead to blue smoke at startup and increased oil consumption. Replacing them during a cylinder head rebuild ensures clean combustion and reduced emissions.

Push Rods

Push rods are critical in transferring camshaft motion to the rocker arms. We offer high-strength push rods for the Cummins 4B engine, engineered for proper length and rigidity. These components are especially important for engines with valve train wear or when converting from flat-tappet to roller lifters.

Our rods are straight-checked and made with durable materials to prevent bending or warping under high loads.

Rocker Arm Nuts

Rocker arm nuts secure the rocker arms onto the push rods and allow for valve lash adjustments. These heavy-duty hex nuts are specifically made for Cummins engines and are essential for maintaining proper valve clearance.

When adjusting valves or servicing the rocker arms, replacing worn or rounded nuts ensures accurate valve timing and reduces the risk of back-off under engine vibration.

Fuel Manifolds

The fuel manifold in a 4B engine ensures balanced fuel delivery to the injectors. Our replacement fuel manifolds are designed for durability and leak-free performance. Whether your manifold has cracked from age or vibration, or you’re rebuilding the top end of the engine, replacing the manifold ensures consistent injection pressure and clean fuel distribution.

Gasket for Push Rod Cover

The push rod cover gasket seals the lower half of the cylinder head to prevent oil leaks along the valve train. This component is often overlooked during head service, but a worn or damaged gasket can lead to oil seepage along the side of the block.

Our push rod cover gaskets are made from high-quality materials and engineered for a perfect fit in the Cummins 4B platform.

Temperature Switches (For Associated Cooling Systems)

For engines using shared cooling system components between Cummins and Detroit Diesel platforms, temperature switches are available that activate at preset temperatures. These are ideal for marine and generator applications where coolant temperature management is critical.

Each switch features the correct thread type and temperature rating to integrate with your engine’s electrical monitoring system and help prevent overheating.

Built to Perform in the Harshest Environments

All of the Cummins 4B cylinder head parts offered by Diesel Pro Power are selected for marine and industrial-grade durability. These components are not designed for passenger vehicles or automotive conversions. Instead, they meet the performance, reliability, and service-life standards required in commercial vessels, generators, and heavy equipment.

Whether you are performing routine top-end service or a complete engine overhaul, having the right cylinder head components makes all the difference. Our team supports over 40,000 satisfied customers around the world with fast shipping, expert guidance, and reliable diesel parts that keep critical equipment running strong.

Why Choose Diesel Pro Power for Your Cummins 4B Cylinder Head Needs?

• Fast Global Shipping – We stock all 4B cylinder head components in our distribution center for rapid delivery worldwide.

• Marine & Industrial Focus – Unlike general auto parts suppliers, we specialize in equipment built for continuous-duty applications.

• Trusted by Professionals – Diesel mechanics, fleet operators, and OEM rebuilders rely on our quality parts and proven performance.

• Outstanding Support – Need help identifying the correct injector tube size or bolt length? Our team is available to assist with technical questions and fitment details.