Maximize the productivity of your heavy equipment under continuous, demanding work cycles. The Workhorse tier cylinder head for the Kawasaki 70ZV wheel loader (QSB 5.9 24-valve electronic engine) is engineered to withstand long shifts, severe thermal expansion, and sustained high-load operations. Assembled using a renewed, pressure-tested OEM core and brand-new, high-quality internal components, this upgraded cylinder head integrates heavy-duty fixes to handle elevated cylinder pressures and eliminate common field failures on the job site.

Upgrades Over the Daily Driver: Precision O-Rings

High-cycle material handling and severe industrial environments generate intense internal heat, causing rapid thermal expansion, the leading cause of head gasket blowouts. The Workhorse model tackles this vulnerability by introducing precision-cut O-rings machined directly into the deck surface. This mechanical modification locks the head gasket securely in place, drastically improving sealing under high cylinder pressures and severe operating temperatures to guarantee zero combustion leaks and prevent costly operational downtime.

Premium Component Breakdown

• Remanufactured Casting: Built from a premium OEM 24-valve core casting that has passed rigorous diagnostic testing and is machined to like-new industrial specifications.

• New Wear Components: Equipped with all-new, high-quality valve seats, valve seals, and valve guides.

Key Features and Heavy-Duty Fixes

This industrial-grade head features critical durability updates, backed by an intense inspection protocol to guarantee every heavy-duty specification is met.

• 40 PSI Pressure Testing: Following all machining work, every cylinder head is pressure-tested at 40 PSI to confirm zero leaks and ensure complete casting integrity before delivery.

• Blow-Proof Plugs: Threaded, blow-proof plugs are installed in the top of the head for superior leak prevention, replacing standard factory pressed-in plugs that prone to failure during severe thermal cycles.

• Final Quality Control: The head undergoes an extensive final cleaning and strict inspection process. A detailed sign-off sheet is generated, measuring and recording critical specifications using a profilometer, including:

  • Valve Recessions

  • Stem Heights

  • Installed Spring Heights

  • Spring Pressures

  • Keeper and Lock Positions

  • Roughness Average (RA) Surface Finish

Precision Machining Process

Choate Engineering Performance has incorporated critical modifications to address common failure points of factory 5.9L 24V cylinder heads, drastically improving field reliability:

• Optimal Sealing Surface: The deck is resurfaced to meet or exceed OEM specifications for Roughness Average (Ra), maximizing the sealing surface performance for the head gasket under high-pressure loading.

• Valve Train Geometry Alteration: We custom blueprint the 24V head to alter valve height and valve recession, achieving maximum durability for high-cycle loader applications.

• Valve Train Longevity Fix: Valve stem heights are precisely altered to optimize geometry and remove excessive preload on the hydraulic lifter. This crucial modification decreases wear and significantly extends the life of the bridges, crossheads, and lifters.

• Optimized Flow and Sealing: Valve seats are cut with a precise three-angle profile to optimize combustion efficiency and ensure a perfect seal.

• Valve Prep: Valves are reground and margins are meticulously inspected to guarantee proper sealing against the new seats.

• All-New Wear Components: New valve stem seals, valve seats, valve guides, and injector cups are installed across the entire assembly.

Meticulous Cleaning and Prep Process

Our commitment to quality begins before machining, with an intensive cleaning and stress-relieving process to ensure a flawless starting point:

• Magnetic Particle Inspection (MPI): Each core is subjected to MPI testing to thoroughly check for any cracks or subsurface imperfections common in high-hour castings.

• Thermal Stress Relieving: The head undergoes a stress-relieving process in a specialized furnace to bake away residual industrial oils and grease.

• Material Relaxation: The head is shot-blasted to strip rust and scale, a crucial step that relaxes the cast iron before any precision machining begins.

• Thread Prep: All broken factory bolts and studs are professionally removed to ensure threads are clean, chased, and ready for a seamless installation.