Eliminate head gasket vulnerabilities and valvetrain fatigue under the absolute harshest operating conditions. The Workhorse Plus tier cylinder head for the Kawasaki 70ZV wheel loader (QSB 5.9 24-valve electronic engine) is engineered specifically for severe-duty industrial applications where equipment breakdown and job site downtime are cost-prohibitive. Assembled using a renewed, pressure-tested OEM core and top-tier internal components, this premium head delivers maximum protection against extreme cylinder pressures, punishing thermal expansion, and continuous high-torque duty cycles.

Upgrades Over the Workhorse Tier: Heavy-Duty Valve Springs

While the Workhorse tier introduces a critical O-ringed deck, the Workhorse Plus upgrades the assembly with premium, heavy-duty valve springs and reinforced retainers. This severe-duty valvetrain configuration prevents valve float and spring fatigue during sustained full-load operation, managing the elevated exhaust backpressures common in industrial turbocharger setups. The result is absolute valvetrain stability and precise tracking when your loader is working at peak operational capacity.

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.

• Precision O-Rings: To combat severe thermal expansion common in high-utilization heavy equipment, precision O-rings are machined directly into the deck surface. This mechanical modification locks the head gasket securely in place, completely eliminating the risk of combustion leaks under extreme loads.

• New Valves: Equipped with all-new, high-quality intake and exhaust valves, verified for precise seating and clearance.

Key Features and Heavy-Duty Fixes

This severe-duty head undergoes an intensive inspection and upgrade protocol to guarantee every critical industrial metric is met.

• 40 PSI Pressure Testing: Following the machining process, every cylinder head is pressure-tested at 40 PSI to verify zero structural leaks and absolute casting integrity.

• Blow-Proof Plugs: Threaded, blow-proof plugs are installed into the top of the head for superior safety, replacing factory pressed-in freeze plugs that regularly fail during severe thermal spikes.

• Final Quality Control: The head undergoes a meticulous final cleaning and rigorous quality control checking. A comprehensive specification sheet is generated, using a profilometer to record:

  • Valve Recessions

  • Stem Heights

  • Installed Spring Heights

  • Spring Pressures

  • Keeper and Lock Positions

  • Roughness Average (RA) Surface Finish

Precision Machining Process

Choate Engineering Performance incorporates structural updates to resolve common factory vulnerabilities of the 5.9L 24V industrial cylinder head, significantly extending operational lifespan:

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

• Valve Train Geometry Alteration: The head is custom blueprinted to adjust valve height and valve recession, optimizing geometry for high-stress industrial applications.

• Lifter and Bridge Longevity Fix: Valve stem heights are precisely machined to remove excessive preload on the lifters, a critical adjustment that dramatically reduces wear and extends the service life of the bridges, crossheads, lifters, and camshaft.

• Optimized Flow and Sealing: Valve seats are cut with an industrial three-angle profile to optimize engine efficiency and ensure an airtight seal.

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

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

Meticulous Cleaning and Prep Process

Our manufacturing protocol begins with an intensive cleaning and stress-relieving process to ensure a flawless casting:

• Magnetic Particle Inspection (MPI): Every single core is subjected to MPI testing to scan for microscopic cracks or subsurface structural imperfections common in high-hour castings.

• Thermal Stress Relieving: Castings undergo a thermal baking process in a specialized furnace to eliminate residual industrial oils and grease by converting them to ash.

• Material Relaxation: The head is shot-blasted to strip away rust and scale. This vital step relaxes the cast iron before any precision machining takes place.

• Thread Restoration: All broken factory bolts and studs are professionally removed, leaving all holes clean, chased, and ready for a seamless installation.