New Cylinder Head 4TNV98 Engine Head Assy for Excavator

Q1: What is the product identification and applicable scope of the original new cylinder head assy for 4TNV98 engines?

Core Product & Compatibility Details

• Product Structure: Delivered as a complete ready-to-install assembly, integrating precision-machined alloy cast iron casting, 8 valves (2 intake + 2 exhaust per cylinder), valve seats, valve guides, injector mounting bores, coolant passages, rocker arm pedestals, and pre-installed sealing gaskets for critical joints. It strictly follows Yanmar’s original design specifications.
• Applicable Engines: Yanmar 4TNV98 (naturally aspirated) and 4TNV98T (turbocharged) engines—optimized for low fuel consumption and reliable performance in intermittent excavator operation.
• Matched Excavators:
  • Yanmar ViO75, ViO80 mini/midi excavators;
  • Kubota KX161-3, KX185-3 compact excavators;
  • Other brand small excavators (e.g., Takeuchi TB260) equipped with 4TNV98 engines.
• Core Application Scenarios: Direct replacement for faulty original cylinder heads (e.g., casting cracks, valve seat wear, coolant leakage, injector bore deformation) and engine overhaul projects, restoring the 4TNV98 engine’s compression ratio, power output, and operational stability for excavators in municipal engineering, garden landscaping, and small-scale earthmoving.

Q2: What core functions does the 4TNV98 cylinder head assy perform for excavator engines?

Core Functions

1. Combustion Chamber Sealing & Pressure Resistance
   • Seals the top of the engine cylinder to form a closed combustion chamber, working with the cylinder block, piston, and head gasket to withstand high combustion pressure (up to 9MPa) and temperature (up to 1050℃). It prevents gas leakage and ensures complete fuel combustion, which directly determines the excavator’s digging force and low-speed torque (≥150N·m @ 1600rpm for 4TNV98T engines).
2. Valve Train Support & Air-Fuel Control
   • Provides precise mounting positions for valves, valve springs, and rocker arms, controlling valve opening/closing timing and duration to optimize the engine’s air-fuel mixture ratio. This enhances fuel efficiency by 5–7% compared to worn or aftermarket non-OEM cylinder heads, reducing operating costs for excavator fleets.
3. Cooling & Heat Dissipation Optimization
   • Features integrated cross-flow coolant passages that circulate coolant around the combustion chamber, injector bores, and exhaust ports, efficiently dissipating excess heat to prevent engine overheating during long-hour excavator operation (e.g., continuous foundation digging). The compact passage design fits the limited engine bay space of small excavators.
4. Fuel Injection System Integration
   • Pre-machined high-precision injector mounting bores ensure accurate positioning of Yanmar original injectors, enabling atomized fuel to be sprayed directly into the combustion chamber at high pressure (up to 120MPa). This improves fuel atomization quality and reduces exhaust emissions, complying with global non-road engine emission standards.
5. Auxiliary Component Mounting Base
   • Serves as the mounting platform for key engine accessories (valve cover, intake/exhaust manifolds, fuel filter bracket, turbocharger adapter for 4TNV98T). Its reinforced design withstands engine vibration (≤12g, 10–2000Hz) during excavator off-road operation, avoiding accessory loosening or damage.