For Conventional Green Coolant

To keep diesel bus engines running and ensure the best life-cycle value, regular cooling system maintenance is vital. Despite the emergence of extended-life coolants, most diesel engines on the road today require the use of conventional green coolants, which must be serviced more frequently. For these bus owners, the Bus Vehicle Center of International Truck and Engine Corporation offers the following tips for servicing diesel engines that use conventional coolant:

• Check coolant level daily.
• If coolant is extremely low and the engine is very hot, let the engine cool for approximately 15 minutes before adding coolant; then, with the engine running, add coolant slowly. Adding cold water to a hot engine may crack the cylinder head or crankcase.
• Only use coolant which has an ethylene glycol base or propylene glycol base antifreeze. Do not use coolant made with methoxy propanol or methyl alcohol. Only use one or the other, don't add propylene glycol to a cooling system that already contains ethylene glycol or vice versa. Both of these antifreezes must be of low silicate (less than 0.10% that meets ASTM D4985 specifications). If higher levels of silicate are used in diesel engines, the effect is

• Top off leaks with the proper mixture of the same antifreeze, water and supplemental coolant additives at the recommended concentration. Do not mix extended life coolants (red in color) with conventional coolants (green in color).
• Use distilled water, not tap water, in the cooling system. Distilled water does not contain chlorine or solids, which corrode the engine.
• Maintain antifreeze concentration by volume between 40 percent (freeze protection to -10⁰F) and 60 percent (freeze protection to -65⁰F) depending on expected surrounding temperature. Never exceed 68 percent concentration because freeze protection is diminished. In addition, the high concentration can plug coolant passages and cause overheating which damages the engine, or deposit on water pump seals causing seal leakage. Minimum concentration of 40 percent should be used to improve boil-over temperature even if freeze protection is not required. Never use water alone.
• Check the coolant for clarity. If the antifreeze is not doing its job, it will cause rust contamination, which turns the coolant stream brown. If it is contaminated, flush and refill the cooling system.
• Flush and refilling the cooling system is recommended every 100,000 miles, 3,800 hours or 24 months.
• To protect the engine from corrosion and cavitation, check the SCA concentration every 12,000 miles, 450 hours or six months using a test kit. Customers can either purchase a test kit from their dealer or have the dealer test the level. If the concentration is off, the SCAs must be replaced with the correct level of units, which can be purchased in filter or liquid form.
• A good reading through a Coolant Test Kit will indicate that the conditioner contained in the coolant is sufficient to insure cooling system protection. Test kit measurements are in units per gallon on International engines. The recommended level is 1.5 to 3.0 units of conditioner per gallon of coolant including make up coolant, with SCA levels never exceeding 3.0 units per gallon. After adding conditioner, run the engine until it is warm enough to circulate conditioner through the cooling system. (International recommends consulting the dealer when calculating the number of units that need to be added, as miscalculation can cause engine damage.
• Check the water hose condition and pliability. The cooling system performs a dual function of transferring heat from the engine and from the lubricating system. If the oil cooler fails, oil can leak into the cooling system and make the hoses too soft. In addition, age can cause hoses to become brittle. Problems with the hose can lead to leaks and downtime.
• If using a liquid SCA, use a non-SCA filter and change the coolant filter every 24,000 miles, 900 hours or 12 months.
• Check the radiator fins periodically to make sure they are free of bugs, leaves or other debris, and that they are not bent or damaged. Clogged or damaged fins prohibit the flow of outside air to the radiator and hamper efficient cooling system operation.

(For specific instruction on draining, cleaning and filling the cooling system, please consult the International^® Engine Operation and Maintenance Manual for International^® DT 466E, 530E and T444E engines.)