ASTM D4340 Standard Test Method for Corrosion of Cast Aluminum Alloys in Engine Coolants Under Heat-Rejecting Conditions
3. Summary of Test Method
3.1 In this test method, a heat flux is established through a cast aluminum alloy typical of that used for engine cylinder heads while exposed to an engine coolant under a pressure of 193 kPa (28 psi). The temperature of the aluminum specimen is maintained at 135°C (275°F) and the test is continued for 1 week (168 h). The effectiveness of the coolant for preventing corrosion of the aluminum under heat-transfer conditions (hereafter referred to as heat-transfer corrosion) is evaluated on the basis of the weight change of the test specimen.

4. Significance and Use
4.1 It is essential that engine coolants prevent heat-transfer corrosion of aluminum cylinder heads during engine operation. Any corrosion products formed may deposit on interior radiator surfaces, reducing heat-transfer efficiency of the radiator. Overheating and boil-over of the cooling system may then occur.

4.2 This test method provides a means for selectively screening unused engine coolants and will readily distinguish those coolants that are unsuitable for use with aluminum cylinder head engines. However, satisfactory performance of a coolant in this test method does not ensure adequate long-term service performance. Additional, more comprehensive evaluations with simulated service, dynamometer, and vehicle tests should be used to establish the long-term effectiveness of the coolant.