Cooling System 76 UENR0623-02 6. Look for air or combustion gas in the cooling system. 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. 7. Inspect the radiator cap for damage. The sealing surface must be clean. If the cooling system is equipped with a sight glass, the coolant should be to the correct level in the sight glass. On cooling systems without an indicator of the coolant level, fill the cooling system in order to be no more than 13 mm (0.5 inch) from the bottom of the filler pipe. 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. Making the Correct Antifreeze Mixtures Do not add pure antifreeze to the cooling system in order to adjust the concentration of antifreeze. Refer to Operation and Maintenance Manual, “Refill Capacities” for the correct procedure. The pure antifreeze increases the concentration of antifreeze in the cooling system. The increased concentration increases the concentration of dissolved solids and undissolved chemical inhibitors in the cooling system. i04169715 Cooling System - Test 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 63 . 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 antifreeze mixture must consist of equal quantities of antifreeze and clean soft water. The corrosion inhibitor in the antifreeze will be diluted if a concentration of less than 50% of antifreeze is used. Concentrations of more than 50% of antifreeze may have the adverse effect on the performance of the coolant.
Checking the Filler Cap One cause for a pressure loss in the cooling system can be a faulty seal on the radiator pressure cap. Personal injury can result from hot coolant, steam and alkali. 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. Illustration 63 g00286266 Cooling system pressure at specific altitudes and boiling points of water Remove filler cap slowly to relieve pressure only when engine is stopped and radiator cap is cool enough to touch with your bare hand. Personal injury can result from hot coolant, steam and alkali.
To check for the amount of pressure that opens the filler cap, use the following procedure: 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. 1. After the engine cools, carefully loosen the filler cap. Slowly release the pressure from the cooling system. Then, remove the filler cap. Remove filler cap slowly to relieve pressure only when engine is stopped and radiator cap is cool enough to touch with your bare hand. 2. Carefully inspect the filler cap. Look for any damage to the seals and to the sealing surface.
Inspect the following components for any foreign substances: 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. Filler cap