Engine overheating

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 expansion tank seam. 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. If problem is not diagnosed, check the coolant system NO - Continue. for engine oil contamination and engine lubrication system for coolant contamination.
4. Are there any external leaks, from hoses, coolant pump, engine gaskets or the heater unit? If the coolant only, or both systems are contaminated, YES - Investigate and rectify. See Adjustment, suspect cylinder head gaskets or radiator. Coolant Requirements NO - Continue. If only the lubrication stystem is contaminated with coolant, suspect inlet manifold or front cover gaskets.
5. Are fan blades fitted correct way round, concave side towards engine? NO - Rectify. YES - Continue.
6. Is viscous unit operating correctly? See Description and operation, Viscous Fan NO - Renew. See Repair, Viscous Coupling YES - Carry out a pressure test on radiator cap and system. Check thermostat type, operation and correct fitting See Repair, Thermostat
7. Is temperature sender and gauge giving accurate readings? NO - Substitute parts and compare readings. YES - Continue.
8. Carry out cylinder pressure test to determine if pressure is leaking into cooling system causing over pressurising and loss of coolant.