TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Cooling System - Air or Combustion Gas Test (008-019)
Section 8 - Cooling System - Group 08
Page 8-23
Pour the test fluid into the combustion gas leak test in-
strument until it is up to the yellow fill line on the instrument.
Insert the rubber tip of the combustion gas leak test in-
strument in the radiator fill neck. Hold the instrument down
firmly while turning back and forth to make sure that an air
tight seal is formed between the tester and radiator fill neck.
Start the engine, and run at high idle for approximately 30
minutes. Monitor the engine temperature and color of the
test fluid during engine operation. Do not allow the engine
temperature to exceed 100C [212F] during the test.
If the color of the test fluid changes from blue to yellow
anytime during the test, combustion gases are leaking into
the cooling system. Discontinue the test if the color of test
fluid changes from blue to yellow.
L-1079