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Cummins NT855 Engine Parts - Cylinder Head Section
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Cylinder Heads & Related Components For Cummins NT855
At Diesel Pro Power, we offer a complete range of cylinder head components for the Cummins NT855 engine—one of the most dependable and widely used industrial diesel engines in the world. Our Cummins NT855 cylinder head products are carefully selected to meet or exceed OEM standards, ensuring lasting performance in heavy-duty applications such as marine propulsion, construction equipment, oilfield machinery, and stationary power systems.
Complete Cylinder Heads for Cummins NT855
Diesel Pro Power carries new Cummins NT855 cylinder heads that come fully assembled with valves and springs. These are ideal replacements for worn or damaged heads and are compatible with all major NT855 configurations, including both Small Cam and Big Cam variants. Whether you're performing a top-end rebuild or a complete engine overhaul, using a new head ensures reliability from the start.
Each NT855 cylinder head we supply is pressure-tested for cracks and casting defects. The installed valve train components are matched to the engine’s valve timing specs, and the assembled head arrives ready for installation.
Key features of our complete NT855 cylinder heads include:
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Pre-installed intake and exhaust valves
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Heavy-duty valve springs
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Hardened valve seats for improved heat resistance
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Precision-machined surfaces for optimal sealing
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Compatible with turbocharged and naturally aspirated models
These heads are especially suited for operators who want to reduce downtime and avoid the hassle of sourcing and assembling individual valvetrain parts. We do not carry remanufactured cylinder heads for this engine—only new, ready-to-install versions for peace of mind and long-term durability.
Intake and Exhaust Valves for Cummins NT855
The NT855 cylinder head supports 12 intake and 12 exhaust valves in its design. These valves operate under extreme temperatures and high pressures, making high-quality replacements critical during top-end servicing.
Our intake valves for the NT855 are manufactured to maintain consistent airflow into the combustion chamber. These standard replacement valves feature a 30-degree seating angle and are heat-treated for long-term reliability in high-duty applications.
Exhaust valves endure significantly higher thermal stress than intake valves. Our NT855 exhaust valves are built from durable alloy materials, making them ideal for engines running under continuous load. These valves are a must-replace component during any cylinder head rebuild due to the thermal fatigue they experience over time.
Valve Springs for Intake and Exhaust Valves
Each NT855 engine uses 24 valve springs—one per valve. These springs maintain pressure against the valve to ensure proper opening and closing cycles, even at high RPMs. Over time, valve springs lose tension and can lead to poor engine performance or even valve float.
Our NT855 valve springs are manufactured to exacting tension specs and are compatible with both intake and exhaust valves. Whether you're replacing a full set or addressing one failed spring, we provide consistent quality that meets Cummins specifications.
Valve Seals and Guides for NT855
Valve stem seals play a critical role in keeping oil from leaking into the combustion chamber while still allowing the valve stem to move freely. NT855 engines require these seals on both intake and exhaust valves to prevent oil consumption and carbon buildup.
Our NT855 valve seals are constructed from high-temperature rubber compounds for durability under extended operating conditions. They are recommended for any rebuild involving valve service.
Valve guides ensure proper valve alignment and limit lateral movement. As these components wear, they can cause oil blow-by and misaligned seating. We offer intake and exhaust valve guides that are machined to factory tolerances and ensure smooth operation across all NT855 variations.
Valve Seat Inserts (Valve Inserts)
Valve inserts sit within the cylinder head and provide a hardened surface for valves to seat against. These are essential for maintaining compression and preventing valve seat erosion. NT855 engines use 24 inserts total—one per valve.
Our inserts are manufactured with high-grade alloy and are compatible with both naturally aspirated and turbocharged NT855 configurations. They are an excellent replacement option when the original seat area shows pitting or wear.
Cylinder Head Gaskets and Upper Gasket Sets
Proper sealing is crucial when reassembling the cylinder head to the NT855 block. Diesel Pro Power offers both individual head gaskets and complete upper gasket sets designed specifically for this engine platform.
Head Gaskets
The Cummins NT855 uses a single-piece head gasket to seal combustion chambers and fluid passages. These gaskets are designed to withstand combustion pressures and coolant/oil flow without failure. It's critical to install a new head gasket any time the cylinder head is removed.
For complete top-end rebuilds, we recommend the NT855 upper gasket set. These kits include the head gasket, valve cover gaskets, intake and exhaust manifold gaskets, and other vital seals needed for a proper reassembly.
Cylinder Head Bolts
Head bolts are subjected to extreme pressure as they secure the cylinder head to the engine block. For the Cummins NT855, 36 cylinder head bolts are required per engine.
We offer high-strength, torque-to-yield head bolts manufactured to Cummins engineering specifications. These bolts are critical for maintaining proper clamp load and preventing head gasket leaks. Always replace cylinder head bolts when installing a new head to avoid uneven torque or fatigue failure.
Push Rods for NT855 Engines
Push rods transmit motion from the camshaft to the rocker arms. The NT855 platform uses different push rods for the valve rocker arms and injector rocker arms, depending on the configuration.
Each NT855 engine requires 12 push rods for the valve rocker arms. These rods must maintain precise dimensions to ensure accurate valve timing. Ours are manufactured to factory length and hardened for wear resistance.
NT855 engines also use 6 additional push rods specifically for injector operation. We carry push rods for both Big Cam and Small Cam NT855 variants, as the lengths and design may differ slightly. Always confirm which version you’re working with before ordering replacements.
Rocker Covers and Gaskets
The rocker cover (valve cover) protects the upper valvetrain components from dirt and oil loss while providing access for maintenance. We supply both styles of rocker covers used in the NT855 engine family, including the original cork gasket design and newer silicone variants.
When replacing or removing the cylinder head, it’s good practice to inspect and replace the rocker cover gasket to avoid future leaks. Whether you're working with the original or upgraded valve cover style, we have you covered.
Supporting Hardware & Components
In addition to core cylinder head parts, Diesel Pro Power supplies all necessary supporting hardware to complete a successful NT855 head replacement:
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Injector Tubes: These transfer fuel from the injector to the combustion chamber. Proper sealing is essential to prevent fuel leaks and maintain pressure.
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O-Rings for Injector Tubes: These seals are inexpensive yet critical. Always replace them during head servicing.
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Temperature Switches: We offer compatible temperature switches that trigger cooling system activation to protect the engine.
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Heavy Hex Nuts: Used for adjusting rocker arm screws. These should be replaced if rounded, stripped, or corroded.
Why Choose Diesel Pro Power for Cummins NT855 Cylinder Head Parts?
With over 40,000 satisfied customers, Diesel Pro Power is the trusted source for Cummins NT855 engine parts. Our catalog is engineered for professional rebuilders and operators who demand reliability, fast delivery, and responsive customer service.
Whether you're performing routine maintenance, repairing a cracked head, or doing a complete top-end rebuild, we have the parts, expertise, and inventory to keep your engine running at peak efficiency.
