This document is a service and repair manual for the cooling system of various Hyster forklift models, specifically the H8-12XM-6, H10XMS-6 (H190-280HD2, H230HDS) [K007]; H13-16XM-6, H10-12XM-12EC (H300-360HD2, H360HD2-EC) [J019]; and H16XM-9, H16XM-12, H18XM-7.5, H18XM-9 (H360-36HD, H360-48HD) [A238]. It provides general guidelines for maintenance and service, intended for use by trained and experienced technicians.
The cooling system is crucial for dissipating heat generated by various truck components, particularly the engine, hydraulic system, and transmission, to maintain controlled operating temperatures. Each of these systems has its own cooling core, which are mounted together in a cooling core assembly, along with a charge air cooler. Heat is dissipated by an airflow pulled through the cooling cores by a belt-driven fan.
Cooling Cores Function and Features:
Cooling cores transfer heat from the internal fluid (coolant or oil) or charge air to the external air. The efficiency of heat dissipation depends on the temperature difference between the air and the core, the volume of air pulled through the core (influenced by fan speed and environmental debris), and the volume of fluid passing through the core.
Factors affecting core efficiency include:
- External insulation: Dust particles forming deposits on the outside of the core can impede heat transfer. Regular cleaning is necessary.
- Fluid flow: Higher engine speeds generally lead to more fluid passing through the core when thermostats are fully open. Charge air flow increases with engine power.
- Internal insulation: Deposits inside the cooling core can impede heat transfer. Hydraulic and transmission oil coolers are less prone to internal deposits due to oil properties and filtration. Charge air coolers may accumulate dust over time.
Fan and Fan Clutch Features:
The fan pulls air through the cooling core assembly. Trucks with Tier 3/Stage III A engines have a fan directly connected to the fan pulley, turning proportionally to engine speed. Tier 4i/Stage III B engines feature a fan clutch to reduce fan speed when lower cooling capacity is sufficient, offering reduced power consumption and noise.
The fan clutch is a viscous coupling between the fan pulley and the fan, varying engagement from 30% to 95% based on engine speed and an electrical Pulse Width Modulation (PWM) signal from the Engine Control Module (ECM). Engagement is achieved by viscous oil between the rotor (connected to the engine pulley) and the housing (carrying the fan). A valve controls oil flow, and a magnet coil, activated by the ECM, adjusts the valve to change fan speed. A speed sensor in the anti-rotation bracket communicates fan speed to the ECM. In case of electrical failure, the clutch engages at maximum.
Clutch engagement is also affected by oil viscosity; it's higher at lower temperatures and lower at higher temperatures. The ECM compensates for these differences. Reaction time for engagement changes depends on viscosity and rotor speed.
Shroud Function:
A shroud on the cooling core assembly enhances fan efficiency by ensuring air is pulled only through the cooling cores. A narrow clearance between the fan and shroud improves efficiency. One-third of the fan extends outside the shroud to allow centrifuged air to escape, increasing propelled air volume. Seals prevent recirculation of warmed air.
Engine Cooling System Components and Operation:
The engine cooling system regulates heat dissipation to maintain optimal engine operating temperature. Key components include:
- Water Pump: Circulates coolant through the engine cooling system and optional cab heater, driven by the crankshaft pulley. Pump supply relates to engine speed but not proportionally.
- Thermostat: Controls coolant flow to the cooling core. Located at the top of the cylinder block, it closes the connection to the radiator when coolant is cold, forcing coolant through a bypass back to the water pump. It starts opening to the cooling core at 82°C (179°F) and is fully open at 91°C (196°F), closing the bypass. Operating without a thermostat can lead to overheating.
- Expansion Tank and Radiator Cap: The expansion tank allows coolant expansion, regulates system pressure, and facilitates de-aeration. The radiator cap houses a pressure valve that releases pressure between 90 kPa (13 psi) and 110 kPa (16 psi) and admits outside air when vacuum is between 2 kPa (0.3 psi) and 7 kPa (1 psi). A fluid level sensor signals the ECM if the coolant level drops below minimum, triggering an engine shutdown within 30 seconds.
- Cab Heater: Located under the cab floor, it uses heated coolant from the cylinder head, with flow controlled by a water valve.
Coolant Specifications:
Coolant is a mixture of water (48%), ethylene glycol (48%), and additives (4%).
- Water: Has the highest heat capacity and lowest cost but limited thermal usage and enhances corrosion. Distilled or deionized water is required to prevent mineral deposits.
- Ethylene Glycol: Extends thermal usage and suppresses corrosion. Optimum mixing ratio with water is typically 50/50. Higher concentrations reduce fluidity and heat capacity but raise the boiling point. Content can be measured with a refractometer.
- Additives: Provide corrosion protection, maintain pH, inhibit scale, de-foam, and protect against liner pitting. OAT type coolants maintain stable pH for up to 5 years. When additives deplete (pH drops below 7.7), coolant must be replaced. Mixing different coolants or additives can cause de-activation of protective additives, gel formation, or deposits.
- Coolant Quality Requirements: When replacing coolant, use an Organic Acid Technology (OAT) based product meeting Cummins requirements CES 14603 and bulletin 3666132. Essential properties include pH between 8.0 and 9.0, reserve alkalinity at least 2.5, total dissolved solids maximum 3,000 ppm, and specific chemical inclusions (nitrite or nitrite/molybdate) and exclusions (chromates, borates, silicates, phosphates, amines).
- Coolant Fill Quantities: Vary by model and engine tier. For example, K007 Engine, Tier 3/Stage III A requires 25.5 liters (6.7 gal), while K007 Engine, Tier 4i/Stage III B requires 19 liters (5 gal).
Charge Air Cooling System:
The turbocharger compresses intake air, which can reach high temperatures. The charge air cooler reduces intake air temperature before it enters the engine, improving performance and lowering emissions.
Transmission Oil Cooling System:
Described in Transmission 1300SRM1455, it includes a thermostat valve between the torque converter outlet port and the cooling core. The thermostat starts opening at 87°C (189°F) and is fully open at 102°C (216°F).
Hydraulic Oil Cooling System:
Hydraulic oil absorbs heat from hydraulic components and returns to the hydraulic tank. A separate gear pump provides oil flow through systems for oil filtration, oil cooling, and brake cooling.
- Oil Filtration and Oil Cooling: Pump supply is filtered by a 5-micron filter element with a 340 kPa (49 psi) bypass valve. A thermostatic valve in the filter adapter starts opening at 65°C (149°F) and fully opens at 80°C (176°F), directing oil to the hydraulic oil cooling core.
- Brake Cooling: A manifold connects supply and return hoses for service and wet brake cooling systems, including a 140 kPa (20 psi) relief valve.
- Hydraulic Control System: Activates fault codes and may reduce engine/vehicle speed if extreme hydraulic oil temperatures are detected. "h-hot" displays when oil temperature exceeds 90°C (194°F), potentially limiting vehicle speed to 10 km/h to reduce braking heat. "h-cold" displays when oil temperature is below -5°C (23°F), reducing engine speed to protect hydraulic pumps.
Maintenance and Repair Features:
The manual outlines detailed checks and procedures:
- Safety Precautions: Emphasizes disconnecting battery, using correct blocks, wearing safety glasses, using correct tools, using Hyster approved parts, and following WARNING and CAUTION notes.
- Cooling System Checks:
- Basic Checks: Inspect cooling core exterior for cleanliness, moisture, and oil (replace leaking cores). Check coolant level (must be above "MIN" when cold). Inspect drive belt for wear, damage, and tension. Check fan blades for wear/damage. Inspect coolant hoses for collapse (indicates defective vacuum valve in radiator cap).
- Coolant Quality Checks: Inspect expansion tank for deposits/rust (indicates quality problem). Perform visual test for clear fluid without cloudiness, debris, or oil (indicates possible head gasket/cylinder liner defect). Perform coolant acidity (pH) test (replace coolant if pH is below 7.7). Perform freeze protection test (check ethylene glycol content with refractometer, adjust if needed).
- Coolant Flow Checks:
- Thermostat: Check for proper opening/closing temperatures (82°C/179°F to 91°C/196°F for engine). Replace if malfunctioning.
- Water Pump: Check for pressure surges in upper radiator hose when engine is revved. If no surges, remove and inspect pump for leaks at weep hole, smooth rotation, and bearing play.
- Cooling Core Efficiency: Measure temperature difference between core entry and exit under specified conditions (e.g., 200°C/360°F charge air, 105°C/190°F engine coolant, 90°C/160°F hydraulic oil, 120°C/215°F transmission oil). Clean and flush if required difference is not met.
- Cooling Core Flow Restrictions: Use a thermometer to check for cold spots on the core, indicating restricted flow. Clean and flush if restrictions are found.
- Engine Leak Tests: Perform if coolant consumption is high, quality fails, pH drops, coolant is in engine oil, or excessive steam from exhaust.
- External Leak Test: Pressurize system to 140 kPa (20 psi) for 5 minutes. Check for leaks at connections, hoses, water pump, cooler core, and engine. Replace water pump if coolant escapes from weep hole.
- Check for Coolant Leak Into Engine Oil Sump: Sample oil from bottom of oil pan and examine for coolant presence (abnormal corrosion inhibitor levels, ethylene glycol, or water).
- Combustion Leak Test: Use a test kit or observe pressure buildup in the expansion tank when engine is started/revved. Release pressure immediately if it reaches 140 kPa (20 psi).
- Engine Cooling System Maintenance:
- Draining: Turn cab heater to hottest setting, let coolant cool, remove radiator cap, open drain valve or loosen coolant return hose.
- Filling: Close drain valve, reinstall return hose, turn heater to hottest, fill with specified coolant until level stabilizes at "MAX."
- Flushing: Drain, refill with clean water, run engine until hot, drain again. Repeat until water is clean. Then refill with cleaner, follow manufacturer instructions, flush twice, and refill with coolant.
- Cleaning: Drain, flush once. Then refill with cleaner, follow manufacturer instructions (max 3 hours to avoid damage), flush twice, and refill with coolant.
- Remove and Replace Procedures: Detailed instructions for drive belt, belt tensioner, water pump, thermostat, and cooling core assembly.
- Drive Belt: Remove by pivoting tensioner counter-clockwise, slipping belt off water pump pulley. For Tier 4i/Stage III B engines, disconnect fan clutch electrical connector and remove anti-rotation bracket bolt. Install in reverse.
- Belt Tensioner: Inspect for slippage at alternator pulley, spring force, play, and smooth rotation. Replace if faulty. Remove by removing drive belt and mounting bolt. Install in reverse, torqueing capscrew to 43 Nm (32 lbf ft).
- Water Pump: Drain cooling system. Remove drive belt, two capscrews, and water pump. Discard O-ring. Install new O-ring, ensuring weep hole is below shaft, install capscrews (torque to 24 Nm/18 lbf ft), install drive belt, refill coolant, and check for leaks.
- Thermostat: Remove, inspect, install.
- Cooling Core Assembly: Removal, disassembly, assembly, and installation procedures.
This manual provides comprehensive guidance for maintaining and repairing the cooling systems of the specified Hyster forklift models, ensuring their safe and efficient operation.
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