Coolant Leak Testing

The cooling system should be full. Add coolant if necessary.

With engine not running, wipe the coolant filler neck sealing seat clean.

Attach a cooling system pressure tester (Special Tool 7700 or equivilent) to the coolant filler neck, as shown and apply 104 kPa (15 psi) pressure. If the pressure drops more than 2 psi in 2 minutes inspect all points for external leaks. For Special Tool identification, see SPECIAL TOOLS .

Move all hoses at the radiator and heater while system is pressurized at 104 kPa (15 psi), since some leaks occur while driving due to engine movement while driving.

If there are no external leaks after the gauge dial shows a drop in pressure, detach the tester. Start engine and run the engine to normal operating temperature in order to open the thermostat and allow the coolant to expand. Reattach the tester. If the needle on the dial fluctuates, it indicates a combustion leak and is usually a head gasket leak.

If the needle on the dial does not fluctuate, race the engine a few times. If an abnormal amount of coolant or steam is emitted from the tailpipe, it may indicate a faulty head gasket, cracked engine block or cylinder head.

There may be internal leaks which can be determined by removing the oil dipstick. If water globules appear intermixed with the oil, it will indicate a internal leak in the engine. If there is an internal leak, the engine must be disassembled for repair.