Investigation of severe corrosion of aluminum parts in stored diesel engine cooling systems

The causes of severe corrosion of aluminum parts in the cooling systems of 250-hp diesel engines during long-term storage were studied. The engines were maintained on a 2-yr schedule that included replacement of the coolant - an inhibited solution of water and ethylene glycol. Three main causes of the corrosion were found, i.e., pitting corrosion initiated by chloride ions present in tap water used for the coolant preparation; inactivation of the applied inhibitors by calcium and magnesium ions present in water; and the development of microbiologically induced corrosion. It is recommended that the coolant mixture should be prepared only with deionized water. For this specific coolant, the field concentration should not be < 30 vol%.