6.2.5. Diagnostics and troubleshooting - 156 - MAINTENANCE OF MAJOR COMPONENTS Complaints Possible causes Corrections 1.
Engine overheating • Lack of coolant • Radiator cap pressure valve spring weakened • Fan belt loosened or broken • Fan belt fouled with oil • Thermostat inoperative • Water pump defective • Restrictions in water passages due to deposit of scales • Injection timing incorrect • Restriction in radiator core • Gases leaking into water jacket due to broken cylinder head gasket • Replenish coolant • Replace cap • Adjust or replace fan belt • Replace fan belt • Replace thermostat • Repair or replace • Clean radiator and water passages • Adjust injection timing correctly • Clean exterior of radiator • Replace cylinder head gasket 2.
Engine overcooling • Thermostat inoperative • Ambient temperature too low • Replace thermostat • Install radiator curtain 3. Lack of coolant • Radiator leaky • Radiator hoses loosely connected or damaged • Radiator cap valve spring weakened • Water pump leaky • Heater hoses loosely connected or broken • Cylinder head gasket leaky • Cylinder head or cylinder block cracked • Correct or replace • Retighten clamps or replace hoses • Replace cap • Repair or replace • Tighten or replace hoses • Replace cylinder head gasket • Replace cylinder head or block 4.
Cooling system noisy • Water pump bearing defective • Fan loosely fitted or bent • Fan out of balance • Fan belt defective • Replace bearing • Retighten or replace fan • Replace fan • Replace fan belt