Cooling System Leak Tests

The system should be full. With the engine not running, wipe the filler neck sealing seat clean.






Attach a radiator pressure tester to the filler neck, as shown, and apply 104 kPa (15 psi) pressure. If the pressure drops more than 2 psi in 2 minutes, inspect the system for external leaks.
Move all hoses at the radiator and heater while system is pressurize at 15 psi, since some leaks occur due to engine rock while driving.
If there are no external leaks after the gauge dial shows a drop in pressure, detach the tester. Start the 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, usually a head gasket leak.

WARNING: WITH THE PRESSURE TESTER IN PLACE PRESSURE BUILDS UP QUICKLY. ANY EXCESSIVE PRESSURE BUILD-UP DUE TO CONTINUOUS ENGINE OPERATION MUST BE RELEASED TO A SAFE PRESSURE POINT. NEVER PERMIT PRESSURE TO EXCEED 138 kPa (20 psi).

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 tail pipe, it may indicate a faulty head gasket, cracked engine block, or cracked 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 indicates an internal leak in the engine. If there is an internal leak, the engine must be disassembled for repair.