SENR9977 47 Testing and Adjusting Section i01889427 Cooling System - Inspect i01964006 Cooling System - Test This engine has a pressure type cooling system. A pressure type cooling system gives two advantages: Remember that temperature and pressure work together. When a diagnosis is made of a cooling system problem, temperature and pressure must be checked. The cooling system pressure will have an effect on the cooling system temperature. For an example, refer to Illustration 53. This will show the effect of pressure on the boiling point (steam) of water. This will also show the effect of height above sea level.
The pressure type cooling system can operate safely at a higher temperature than the boiling point of water at a range of atmospheric pressures. The pressure type cooling system prevents cavitation in the water pump. Cavitation is the sudden generation of low pressure bubbles in liquids by mechanical forces. The generation of an air or steam pocket is much more difficult in a pressure type cooling system. Regular inspections of the cooling system should be made in order to identify problems before damage can occur. Visually inspect the cooling system before tests are made with the test equipment. Visual Inspection Of The Cooling System 1. Check the coolant level in the cooling system.
g00286266 Illustration 53 2. Look for leaks in the system. Cooling system pressure at specific altitudes and boiling points of water 3. Inspect the radiator for bent fins and other restriction to the flow of air through the radiator. 4. Inspect the drive belt for the fan. Personal injury can result from hot coolant, steam and alkali. 5. Inspect the blades of the fan for damage. At operating temperature, engine coolant is hot and under pressure. The radiator and all lines to heaters or the engine contain hot coolant or steam. Any contact can cause severe burns. 6. Look for air or combustion gas in the cooling system. 7. Inspect the radiator cap for damage. The sealing surface must be clean.
Remove filler cap slowly to relieve pressure only when engine is stopped and radiator cap is cool enough to touch with your bare hand. 8. Look for large amounts of dirt in the radiator core. Look for large amounts of dirt on the engine. 9. Shrouds that are loose or missing cause poor air flow for cooling. The coolant level must be to the correct level in order to check the coolant system. The engine must be cold and the engine must not be running. After the engine is cool, loosen the pressure cap in order to relieve the pressure out of the cooling system. Then remove the pressure cap. The level of the coolant should not be more than 13 mm (0.5 inch) from the bottom of the filler pipe.
If the cooling system is equipped with a sight glass, the coolant should be to the correct level in the sight glass.