Cummins QSB 6.7 Parts - Piston Kit Section

Cummins QSB 6.7 Piston Kit Catalog

The Cummins QSB 6.7 engine is a workhorse across marine, industrial, agricultural, and construction applications. Known for its durability, power delivery, and emission compliance, it is essential that replacement parts like piston kits meet the original engine’s design standards. Diesel Pro Power supplies complete piston kits and supporting components for QSB 6.7 engines to support reliable rebuilds and performance optimization.

Overview of the QSB 6.7 Piston Design

The Cummins QSB 6.7 uses a one-piece steel or aluminum piston designed to deliver strength and efficient combustion under high-cylinder pressures. These pistons typically feature:

• Integrated combustion bowls to promote cleaner fuel burn.

• Coated skirts for reduced friction and extended life.

• Durable steel piston pins to withstand high thermal and mechanical loads.

• Heat-treated ring lands for superior wear resistance.

Each piston kit is assembled with the essential components for one cylinder, including piston, pin, retaining clips, and optional ring sets and liners where applicable.

Compatibility by CPL Number

Cummins engine rebuilds depend heavily on the engine’s CPL (Control Parts List) number, which ensures that the piston geometry, compression ratio, and bore tolerances match the intended application. The piston kits available for the QSB 6.7 platform at Diesel Pro Power support numerous CPL configurations, such as:

• CPL 1982, 1995, 1989, 1998, 2048 – Typically found in marine auxiliary and genset applications.

• CPL 3602, 8529, 8530, 8781, 8782 – Frequently installed in newer Tier 3 and Tier 4 industrial platforms.

• CPL 426, 427, 656, 1100 – Popular across generator packages and export models.

• CPL 1584, 1610, 1629, 1700, 1701, 2605, 2743 – Used in both propulsion and auxiliary roles in marine environments.

• CPL 8466, 8510, 8611, 8615, 8725, 8733, 8754, 8755, 8756 – Common in updated QSB models with improved emissions and turbo systems.

When choosing your piston kit, confirm your CPL number to ensure proper fitment and performance.

What’s Included in Each Piston Kit

Each Cummins QSB 6.7 piston kit available from Diesel Pro Power is designed for direct-fit installation and includes:

Piston Assembly

• One-piece piston construction

• Standard bore size (for standard rebuilds)

• Engineered for high thermal load

• Coated skirt for low wear and noise

Wrist Pin (Piston Pin)

• Hardened steel construction

• Interference or slip-fit design based on CPL

Pin Retainers

• Two per piston

• Prevent lateral movement of the pin

Optional Add-Ons

• Cylinder liner (standard bore size) if required by engine block condition

• Piston ring set matched to piston specifications

All components are brand-new and sourced to meet or exceed OEM specs for QSB 6.7 engines.

Piston Ring Sets for QSB 6.7

To achieve proper compression, oil control, and minimal blow-by, the ring set is just as critical as the piston itself. Diesel Pro Power offers ring sets that match piston kit specifications exactly and are sold separately for flexibility.

Ring Set Features:

• Three-piece design: Compression ring, intermediate scraper, and oil control ring

• Chrome or moly-coated surfaces for extended life

• Precision-cut ring gaps to reduce oil consumption and improve sealing

• Ring sets are individually matched to piston kits based on CPL requirements

Each ring set is designed for a single piston and should always be replaced during any top-end or full overhaul.

Cylinder Liners for QSB 6.7

Some QSB 6.7 engine blocks are serviceable with wet or dry liners, depending on the version and rebuild requirements. Cylinder liners are available in standard size and are matched to the correct piston geometry. They are commonly required when:

• The engine block has experienced scoring or wear

• A rebuild requires re-sleeving for standard bore restoration

• OEM tolerances must be maintained for emissions and fuel efficiency

Key Benefits:

• Extended block life with standard reconditioning

• Allows reuse of connecting rods and crankshaft journals

• Restores cylinder roundness and concentricity

• Saves time compared to oversize machining

Compression Ratio and What It Means

While the QSB 6.7 pistons are typically standard across many CPLs, compression ratios may vary depending on the engine’s emissions configuration and turbo system. Compression ratio refers to how much the air-fuel mixture is compressed in the cylinder before ignition. A higher ratio often provides more torque and fuel efficiency but may require tighter manufacturing tolerances and specific ring setups.

Common Ratios:

• 17.3:1 – For high-efficiency marine genset and industrial use

• 16.5:1 – For moderate boost turbo setups

• 15.5:1 – For Tier 3+ engines with advanced emissions control

Always match piston kits with the correct compression ratio based on CPL and intended use.

Applications of the Cummins QSB 6.7 Engine

Piston kits for the QSB 6.7 engine are used across diverse platforms, including:

Marine

• Auxiliary generators for yachts and commercial vessels

• Propulsion systems for fishing vessels and patrol boats

• Hydraulic pumps and winch systems for marine equipment

Industrial

• Stationary power generators (prime or standby)

• Mining and quarrying equipment

• Forklifts and mobile cranes

• Water pumps and oilfield support equipment

Agricultural and Off-Highway

• Tractors and harvesters

• Irrigation engines

• Earthmovers and graders

Each of these environments places unique stress on pistons due to load profiles, fuel quality, and cooling systems. Diesel Pro Power ensures all piston kits meet the demands of these applications.

Signs Your QSB 6.7 Pistons Need Replacement

Don’t wait for a complete engine failure. If you notice any of the following symptoms, it may be time for a top-end rebuild with new pistons:

• Loss of compression or blow-by at the crankcase breather

• Blue or white exhaust smoke during acceleration or cold starts

• Abnormal piston slap or knocking sounds

• Increased oil consumption or visible oil residue in the exhaust

• Scoring or damage to cylinder walls

Routine inspections and compression tests can help identify worn piston rings or pistons early—allowing for scheduled rebuilds before major damage occurs.

Choosing the Right Kit for Your Rebuild

When ordering piston kits for your QSB 6.7 engine, always:

1. Confirm the CPL number on your engine’s dataplate

2. Assess the block condition to determine whether new liners are required

3. Replace the ring set any time the piston is replaced

4. Order one kit per cylinder – QSB 6.7 engines are inline 6-cylinder configurations

For full overhauls, consider pairing piston kits with compatible main bearings, rod bearings, and a top gasket set.

Why Buy Your QSB 6.7 Piston Kits from Diesel Pro Power?

With over 40,000 satisfied customers worldwide, Diesel Pro Power has become the trusted source for Cummins engine components. Our piston kits are:

• In stock and ready to ship globally

• Backed by a comprehensive warranty

• Supported by easy online ordering and customer service in English and Spanish

• Matched by CPL to ensure proper fit and reliability

• Designed for marine, industrial, and off-highway use

We make it simple to get the exact parts you need without the guesswork.