1. Inoperative pressure cap

2. Defective thermostat and gasket leakage at thermostat housing

3. Loose, slipping or missing fan belt.

4. Radiator overflow overfilled. Defective radiator. Clogged water passage in radiator core, engine water jackets.

5. Loose hose connections or hose obstructed because of interior deterioration or collapse at a bend point.

6. Leaking or defective water pump.

7. Bent or missing fan blades

8. Air passages through radiator core plugged with insects leaves or debris. (Blow clear wit air or garden hose)

9. Internally blown or damaged head gasket, loose head bolts, or warped or cracked cylinder head or engine block.

10. Wrong grade of gasoline or low oil level.

11. Engine improperly timed or ignition faulty. Automatic vacuum control or distributor not operating properly

12. Insufficient anti-freeze in winter (freezing), low boiling point anti-freeze with high temperature thermostat, or non-recommended antifreeze material.

13. verheated engine, frequent starts and stops in heavy traffic, excessive idling, high speeds on hot days, pulling heavy loads on long grades, dragging brakes. All these conditions and combinations thereof are emphasized at higher altitudes.