1. Insufficient coolant in system.
2. Water pump drivbelt defective or not adjusted properly.
3. Radiator core blocked or radiator grille dirty and restricted.
4. Thermostat faulty.
5. Fan blades broken or cracked.
6. Radiator cap not maintaing proper pressure. Have cap pressure tested by a gas station.
7. Ignition timing incorrect.

2. Overcooling

1. Thermostat faulty.
2. Inaccurate temperature gauge or sending unit.

3. External coolent leakage

1. Deteriorated or damaged hoses or loose clamps. Replace hoses and/or tighten clamps at hose connections.
2. Water pump seals defective. If this is the case, water will drip from the weep hole in the water pump body.
3. Leakage from radiator core or header tank. This will require the radiator to be professionally repaired.
4. Engine drain plugs or water jacket core plugs leaking.

1. Leaking cylinder head gasket. Have the cooling system pressure tested.
2. Cracked cylinder bore or cylinder head. Dismantle engine and inspect.

1. Too much coolant in the system.
2. Coolant boiling away due to overheating.
3. Internal or external leakage.
4. Faulty radiator cap. Have the cap pressure tested.

1. Inoperative water pump. A quick test is to pinch the top radiator hose closed with your hand while the engine is idling, then let it loose. You should feel the surge of coolant if the pump is working properly.
2. Restriction in cooling system. Drain, flush and refill the system. If necessary, remove the radiator and have it reverse flushed.
3. Water pump drivebelt defective or not adjusted properly.
4. Thermostat sticking.