The Ford procedure, “Engine Test for Coolants in Aluminum Systems,” was used to demonstrate aluminum transport deposition in a Ford Escort engine with a silicate-containing coolant. Evidence of aluminum transport was gathered from physical and chemical analysis of coolant samples, corrosion specimen weight losses, and inspection of cooling system components. The loss of hot surface aluminum protection corresponded with the depletion of silicate from solution during the test. Corrosion of heat-rejecting aluminum surfaces led to the presence of aluminum in solution, and the resultant deposition of aluminum phosphate in the radiator. Inspection of the coolant passages of the aluminum cylinder head at the completion of the test showed evidence of extensive corrosion.

In a second dynamometer test, it was shown that aluminum transport deposition can be prevented by the use of a coolant with adequate silicate stability. In this case, the silicate concentration remained high enough to insure hot surface aluminum protection throughout the test. Evaluation of the radiator at the completion of the test showed essentially no loss of heat rejection capacity. Inspection of the cylinder head showed no signs of corrosion.