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COOLING SYSTEM 1 FAULT DIAGNOSIS ENGINE OVERHEATING Before conducting any cooling system diagnosis: See Description and operation, Engine Cooling 1. Is coolant level correct? NO - Allow engine to cool, top up level to YES - Continue. 2. Is coolant in radiator frozen? YES - Slowly thaw and drain system. See Adjustment, Coolant Requirements NO - Continue. 3. Is air flow through radiator restricted or blocked? YES - Apply air pressure from engine side of radiator to clear obstruction. NO - Continue. 4. Are there any external leaks, from hoses, coolant pump, engine gaskets or the heater unit? See Adjustment, Coolant Requirements NO - Continue. 5. Are fan blades fitted correct way round, concave side towards engine? Rectify. YES - Continue. 6. Is viscous unit operating correctly? See Description and operation, Viscous Fan Renew. See Repair, Viscous Coupling YES - Carry out a pressure test on radiator cap and system. Check thermostat type, See Repair, Thermostat 7. Is temperature sender and gauge giving accurate readings? Substitute parts and compare readings. YES - Continue. 8. Carry out cylinder pressure test to determine if pressure is leaking into cooling system causing If problem is not diagnosed, check the coolant system If the coolant only, or both systems are contaminated, If only the lubrication stystem is contaminated with |