Air in the coolant can result in loss of coolant from the overflow when the aerated coolant is hot. The heated air
expands, increasing the pressure in the system, causing the cap to open.
Similarly, coolant can be displaced through the overflow if the head gasket or a crack in the cylinder head leaks
compression gases to the cooling system.
NOTE: All cab heaters and air conditioners must be turned off, and the engine fan control must be turned to
the AUTOMATIC position, if applicable.
NOTE: Install the test equipment at the expansion tank filler neck on Marine applications.
Remove the radiator cap, and leave it off for the following test.
