Cummins 6CT Engine Parts – Gasket Section

The Cummins 6CT 8.3 is one of the most respected mid-range heavy-duty engines, relied upon in marine, industrial, construction, and agricultural applications worldwide. For an engine of this caliber, maintaining proper sealing and preventing fluid or gas leaks is critical to performance and reliability. Gaskets form the backbone of these sealing systems, ensuring tight connections between components such as cylinder heads, intake and exhaust manifolds, oil coolers, and water pumps.

Diesel Pro Power offers a comprehensive catalog of Cummins 6CT gaskets, seals, and gasket kits—designed for both standard rebuilds and marine applications. With more than 40,000 satisfied customers worldwide, our catalog covers everything from single replacement seals to full upper and lower gasket sets.

Cylinder Head & Upper Engine Gaskets

Head Gasket for Cummins 6CT

The head gasket is one of the most critical sealing elements in any diesel engine. On the Cummins 6CT, it ensures a secure seal between the cylinder head and the block, maintaining compression while preventing coolant and oil from mixing. Standard head gaskets are available for engines rated up to 230 HP, making them ideal for marine propulsion systems, generators, and industrial equipment in this power range.

Key Benefits:

• Maintains combustion chamber pressure for efficiency and power.

• Prevents oil and coolant cross-contamination.

• Designed to handle the thermal expansion of the 6CT engine.

Cummins 6CT Upper Gasket Set

The upper gasket set is essential during top-end rebuilds, typically including the head gasket, intake and exhaust manifold gaskets, valve cover gaskets, injector seals, and other upper sealing components. For Cummins 6CT engines rated at 450 HP and below, this kit simplifies ordering and ensures all necessary gaskets are on hand during maintenance.

Applications:

• Marine top-end rebuilds.

• Cylinder head replacement or reconditioning.

• Valve and rocker cover maintenance.

Lower Engine Gaskets

Cummins 6CT Lower Gasket Set

The lower gasket set covers the sealing needs of the bottom end of the engine. It usually includes gaskets for the oil pan, rear cover, gear housing, oil cooler, and front cover. By using a complete set, mechanics avoid the risk of mismatched materials or dimensions that could lead to leaks.

Typical Uses:

• Overhaul or rebuild procedures.

• Resolving oil leaks in older 6CT engines.

• Long-term preventative maintenance for high-hour marine engines.

Intake & Exhaust Gaskets

Exhaust Manifold Gasket

The 6CT engine requires six exhaust manifold gaskets per engine. These gaskets prevent hot exhaust gases from escaping between the cylinder head and the manifold, ensuring proper turbocharger performance and avoiding power loss.

Exhaust Manifold Outlet Connection Gasket

This gasket seals the connection where exhaust gases exit the manifold and enter the turbo or piping. A proper seal helps prevent exhaust leaks, which could otherwise reduce turbo efficiency and increase backpressure.

Turbo Mounting Gasket

For water-cooled turbochargers, this gasket ensures leak-free operation where the turbo mounts to the manifold. Proper sealing here is crucial to maintaining both boost pressure and coolant circulation.

Intake Manifold Cover & Connection Gaskets

The intake system requires precision sealing to prevent air leaks that could disrupt engine performance. Cover and connection gaskets are designed for the high airflow demands of the 6CT, ensuring every cylinder receives consistent, pressurized air.

Cooling System Gaskets

Marine Raw Water Pump Mounting Gasket

For marine applications, a gasket is required to mount the raw water pump securely to the engine. This gasket prevents saltwater leaks that could corrode surrounding components or reduce cooling efficiency.

Marine Water Pump O-Rings

The Cummins 6CT uses specific O-rings at the inlet and outlet ports of the raw water pump. Each engine requires two O-rings, which are designed to handle continuous exposure to seawater while resisting swelling or degradation.

Heat Exchanger Gasket

Engines like the 6C, 6CT, 6CTA, and QSC often rely on a marine heat exchanger for cooling. The 5-inch diameter heat exchanger gasket ensures tight sealing, preventing coolant leaks that could compromise marine engine reliability.

Thermostat Gasket

Located at the thermostat housing, this gasket ensures a secure seal to maintain proper coolant flow regulation. A reliable thermostat gasket is essential to keep engine temperature within the optimal range.

Oil System Gaskets

Oil Cooler Gaskets

The oil cooler requires both an inner and outer cover gasket. These gaskets ensure that engine oil remains properly routed through the cooler without leaks. If these gaskets fail, oil pressure may drop or coolant contamination could occur.

Oil Cooler Cover Gasket

Both inner and outer cover gaskets are available for complete oil cooler servicing. Using fresh gaskets during oil cooler maintenance or replacement ensures long-term sealing reliability.

Gear Housing & Cover Gaskets

Gear Cover Gasket

The gear cover gasket seals the front timing gear cover, preventing oil leaks from the gear train area.

Gear Housing Gasket

This larger gasket is critical for sealing the gear housing to the block. Because the gear housing contains moving parts under high stress, precision sealing is necessary to avoid oil leaks and maintain correct lubrication.

Rear Cover Gasket

Sealing the rear cover plate, this gasket prevents oil leakage from the back of the engine. It is particularly important in marine installations where space is tight and even minor oil leaks can create hazards.

Valve Train Gaskets

Valve Cover Gasket

The valve cover gasket provides a seal between the cylinder head and the valve cover, preventing oil seepage. On a Cummins 6CT, this gasket is exposed to constant temperature fluctuations, requiring a durable material that resists hardening.

Fuel & Auxiliary Gaskets

Fuel Transfer Pump Gasket

Each fuel pump requires two gaskets, ensuring that diesel fuel is delivered to the engine without leaks or air intrusion.

Water Pump & Seal Gaskets

Engine Fresh Water Pump Seal

This seal prevents leaks in the engine’s freshwater pump, ensuring that coolant circulates effectively through the block and head.

Sealants, Compounds & Gasket Makers

Beyond traditional gaskets, Cummins 6CT maintenance often involves high-temperature sealants and gasket makers for added reliability. Diesel Pro Power stocks a wide selection of professional-grade products, including:

• Hi-Temperature Jointing Compound – For turbocharger and extreme heat applications.

• High Tack Sealant Spray – Ideal for holding gaskets in place during assembly.

• Liquid Gasket Maker – Used where cut gaskets are impractical.

• Sensor-Safe Silicone RTV – Protects sensitive sensors while forming a durable seal.

• Cold Weld Compounds – Emergency repairs or reinforcement of sealing surfaces.

• Non-Hardening Pliable Sealant – Stays flexible in vibration-intense environments.

These products ensure mechanics and operators have flexible sealing solutions when traditional gaskets alone are not enough.

Why Choose Diesel Pro Power for Cummins 6CT Gaskets

• Comprehensive Coverage: From small O-rings to complete gasket sets, everything needed for Cummins 6CT engines is available in one place.

• Marine & Industrial Focus: Components designed to withstand the harsher conditions of seawater cooling and continuous operation.

• Global Reliability: With more than 40,000 satisfied customers worldwide, Diesel Pro Power is the trusted supplier for Cummins parts.

• Fast Shipping: Same-day shipping ensures downtime is minimized, no matter where you are located.