Pressure Tester Method
The engine should be at normal operating temperature. Recheck the system cold if the cause of coolant loss is not located during the warm engine examination.
Carefully remove the radiator pressure cap from the filler neck and check coolant level. Push down on cap to disengage it from the stop tabs. Wipe the inside of filler neck and examine the lower inside sealing seat for nicks, cracks, paint, dirt and solder residue. Inspect the radiator-to- reserve/overflow tank hose for internal obstructions. Insert a wire through the hose to be sure it is not obstructed.
Inspect cams on the outside of filler neck. If the cams are damaged, seating of the pressure cap valve and tester seal will be affected.
Attach pressure tester (7700 or an equivalent) (1) to radiator filler neck.
Operate tester pump to apply 124.1 kPa (18 psi) pressure to system. If hoses enlarge excessively or bulge while testing, replace as necessary. Observe the gauge pointer and determine the condition of the cooling system according to the following criteria:
Holds Steady: If the pointer remains steady for two minutes, serious coolant leaks are not present in system. However, there could be an internal leak that does not appear with normal system test pressure. If it is certain that coolant is being lost and leaks cannot be detected, inspect for interior leakage or perform Internal Leakage Test. Refer to INTERNAL LEAKAGE INSPECTION .
Drops Slowly: Indicates a small leak or seepage is occurring. Examine all connections for seepage or slight leakage with a flashlight. Inspect radiator, hoses, gasket edges and heater. Seal small leak holes with a Sealer Lubricant (or equivalent). Repair leak holes and inspect system again with pressure applied.
Drops Quickly: Indicates that serious leakage is occurring. Examine system for external leakage. If leaks are not visible, inspect for internal leakage. Large radiator leak holes should be repaired by a reputable radiator repair shop.