LO 11-8 Outline maintenance procedures and identify tools and methods used to perform maintenance on a diesel engine cooling system

Preventive Maintenance for Cooling Systems

The following tasks help keep a diesel engine’s cooling system in good working order:

• Pressure test the radiator cap to check for the recommended system pressure level.
• Check the thermostat for proper opening and closing.
• Pressure test the system to identify any external leaks in the cooling system, including the radiator, water pump, engine cooling passages, radiator and heater hoses, cylinder head gasket, and heater core.
• Visually inspect the coolant color and condition to check for oil, transmission, and fuel leakage into the cooling system.
• Visually inspect all cooling system components, including belts, hoses, and belt tensioners.
• Test the engine fan clutch for proper operation.
• Measure the freeze protection of the coolant using a refractometer or hydrometer Figure 73.
• When conventionally formulated, type I antifreeze is used, measure nitrite/nitrate levels to indicate correct levels or DCA/SCA. This can be done using coolant test strips or other chemical tests at every oil change interval by dipping test strips into the coolant through the radiator opening. Test strips may also indicate pH level, ratio of glycol, and other levels of corrosion inhibitors. Note that test strips should not be used to check excessively hot or cold coolant. Ideally, coolant should be at room temperature for correct chemical analysis.
• Complete a lab analysis of the additive package in ELC at 300,000 miles (482,800 km). Field test kits are not currently available to evaluate levels of SCA or DCA.
• If preferred, add extender to HOAT and NOAT ELC at 300,000 miles (482,800 km).
• Flush and fill the cooling system every 200,000 miles (321,900 km) or every 2 years if conventionally formulated, type I antifreeze is used and every 600,000 miles (965,600 km) if ELC is used.

FIGURE 11-73: Verifying correct freeze protection for either propylene or ethylene glycol using a refractometer.