6. COOLING SYSTEM MXU 500 IRS COOLING SYSTEM TESTING Cap Tester RADIATOR CAP INSPECTION Remove the radiator cap (refer to the "COOLANT REPLACEMENT" section in this chapter). Pressure test the radiator cap. Replace the radiator cap if it does not hold Radiator Cap pressure, or if relief pressure is too high or too low. It must hold the specified pressure for at least six seconds. Before installing the cap in the tester, wet the sealing surface. Cap Tester Radiator Cap Relief Pressure: 90 kPa (0.9 kg/cm, 12.8 psi) Pressurize the radiator, engine and hoses, and check for leaks. Excessive pressure can damage the cooling system components. Do not exceed 105 kPa (1.05 kg/cm, 14.9 psi). Repair or replace components if the system will not hold the specified pressure for at least six seconds. COOLANT REPLACEMENT PREPARATION The effectiveness of coolant decreases with the accumulation of rest or if there is a change in the mixing proportion during usage. Therefore, for best performance change the coolant regularly as specified in he maintenance schedule. Mix only distilled, low mineral water with the antifreeze. Recommended mixture: 1:1 (Distilled water and antifreeze) 6-5