Cummins QSB 5.9 Overhaul Kits – Complete Rebuild Solutions by CPL

Diesel Pro Power offers complete Cummins QSB 5.9 rebuild kits tailored by CPL (Control Parts List) number, ensuring a perfect fit for your industrial or marine diesel engine. Whether you're dealing with loss of compression, excessive blow-by, poor fuel economy, or coolant in the oil, these engine overhaul kits include the components needed to return your QSB 5.9 to OEM-level performance.

Each overhaul kit is designed for long-term durability and reliable fit, with quality components that meet or exceed Cummins specifications. Below you’ll find a breakdown of the Cummins QSB 5.9 rebuild kit we carry, compatible CPL numbers, and supporting parts and tools necessary for a successful engine rebuild.

Engine Overview: Cummins QSB 5.9

The Cummins QSB 5.9 is a widely used 6-cylinder diesel engine known for its reliability in heavy-duty equipment, marine vessels, and industrial applications. Built with electronic controls and high-pressure common-rail fuel injection, the QSB5.9 offers low emissions and strong performance in a compact package.

• Displacement: 5.9 liters (359 cubic inches)

• Configuration: Inline 6-cylinder

• Fuel System: High-pressure common-rail

• Cooling: Liquid-cooled

• Typical Applications: Marine propulsion, generator sets, agricultural tractors, loaders, excavators, construction equipment

Overhaul Kit for Cummins QSB5.9 (CPL 8464, 8732)

Key Features:

• Compatible with CPL numbers 8464 and 8732

• Includes pistons, rings, liners, rod bearings, main bearings, thrust washers, gaskets, and seals

• Designed for standard size rebuilds

• Compression ratio: 17.2:1

• This means the air-fuel mixture is compressed to 1/17.2 of its original volume before ignition, producing efficient combustion with strong torque output

This kit supports engines with rear gear train configurations and standard bore size. If your pistons are oversized or your block has been bored previously, confirm measurements before installation.

Signs it’s time for a rebuild:

• Difficulty starting when cold

• Decreased engine power under load

• Elevated crankcase pressure or excessive oil vapor

• Evidence of fuel dilution or coolant in the oil

Supporting Components & Tools for a Complete Rebuild

A successful overhaul requires more than pistons and gaskets. Below are essential components and tools available for QSB 5.9 rebuilds:

Piston Cooling Nozzles

• Designed to maintain piston temperature by spraying oil onto the piston underside

• Critical for preventing piston seizures and excessive wear during high-load operation

• One required per cylinder

Front Crankshaft Seal Kits

• Includes the front crank seal and installation sleeve

• Prevents oil leakage at the crank pulley seal location

• Available in multiple variants: one with a dust shield and one with a plain sleeve—verify which your CPL requires

Rear Crankshaft Seal Kits

• Contains a double-lip seal and installation sleeve for engines with a wet clutch housing

• Prevents rear main oil leaks and premature clutch contamination

Recommended Service Tools

Feeler Gauge (.002” to .025”)

• Required for valve lash adjustment

• Valve clearance must be reset after head removal to maintain proper engine timing and breathing

Piston Ring Assembly Tool

• Ensures correct installation of piston rings without overstressing or breaking them

• Compatible with Cummins QSB 5.9 and similar engines

Fuel Filter Wrench (3-7/16" to 3-3/4")

• Simplifies removal of spin-on style fuel filters without damaging the filter housing

• Especially useful in confined marine engine compartments

Oil Filter Wrench (4-21/32” to 5-5/32”)

• Adjustable design fits a wide range of oil filter sizes for easy removal and installation

• Prevents over-tightening which can damage filter gaskets

Essential Filters & Consumables

Cummins Oil Filter

• Spin-on style, standard for QSB 5.9

• Helps remove soot, metal, and other contaminants from the lubrication system

• Replace with every oil change and during rebuilds

Fuel Filter and Water Separator

• Protects the high-pressure fuel system from particulates and water intrusion

• Should be replaced when performing any engine rebuild or fuel system service

• Keep a spare on hand for remote field or marine operations

Cooling System Maintenance

Radiator Cleaner

• Non-corrosive cleaning solution for diesel engine radiators

• Removes scale, rust, and oil residue from coolant channels

• Always flush and clean cooling systems before returning a rebuilt engine to service

Electrical & Monitoring Accessories

Temperature Switch

• Closes at 205°F to activate alarms or shutdowns for over-temperature protection

• Commonly installed in marine and industrial generator sets

Gauges

• Available in mechanical and electrical variants (12V or 24V)

• Use oil pressure and temperature gauges to monitor engine performance after rebuild

• Optional models include alarm contacts for remote safety panels

Why Buy Your QSB 5.9 Rebuild Kit from Diesel Pro Power?

With over 40,000 satisfied customers worldwide, Diesel Pro Power is a trusted leader in diesel engine parts distribution. Our Cummins QSB5.9 rebuild kits are matched to specific CPLs, helping you avoid the guesswork and compatibility issues that often occur when ordering from generic suppliers.

• Fast shipping across North America and globally

• In-stock guarantee on most major components

• English and Spanish support from real diesel engine experts

• Marine and industrial focus—no automotive crossover

How to Identify Your CPL Number

Your engine’s CPL (Control Parts List) number is a critical identifier that ensures correct fitment of pistons, gaskets, and liners. Look for the CPL stamped on the dataplate located on the gear housing or valve cover. Never guess—an incorrect CPL match can result in piston clearance issues, gasket leaks, or incompatible timing gear specifications.

If you need help identifying your CPL, contact our support team for assistance.

When Should You Overhaul a Cummins QSB5.9?

Common signs that a rebuild is needed include:

• Noticeable drop in compression on one or more cylinders

• Excessive crankcase blow-by or oil leaking from the breather tube

• Coolant consumption with no external leak (possible liner cavitation)

• Fuel dilution in the oil (indicates poor injector sealing or worn rings)

• Poor fuel economy or rough idle

If your engine is showing more than one of these signs, especially combined with high hours or miles, it’s time to consider an overhaul.