Pressure Testing
Remove radiator cap. Inspect radiator and radiator cap sealing surfaces. Many radiators use plastic filler neck. The sealing surface of this plastic may distort if vehicle has overheated.
Install pressure tester on radiator cap. Increase pressure slowly and observe pressure tester gauge. Replace radiator cap if pressure is not released as specified on radiator cap. See Fig 1 .
Install pressure tester and pressurize cooling system to radiator cap specification. Inspect all hose connections, water pump, radiator and engine for any signs of leakage. Correct any leaks. See Fig 2
Release pressure, but leave pressure tester connected. Start and run engine for a few minutes while observing pressure tester. If pressure build up rapidly, a compression leak to cooling system is indicated. Check for possible defective head gasket, improper head bolt torque and cracked cylinder head.
Commercially available testers can be used to identify cylinder compression leaks into cooling system by detecting gasoline fumes (Hydrocarbons) at radiator fill neck.