Cooling System Leak Testing
Special Tools
- J-24460-A Cooling System Pressure Tester
- KM-471 Pressure Tester Adapter
- KM-6327-A Cooling System Test Adapter
Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.
In order to help avoid being burned, do not remove the radiator cap while the engine and the radiator are hot. Scalding fluid and steam can be blown out under pressure if the cap is removed too soon.
- Remove the coolant pressure cap.
- Test the operation of the coolant pressure cap. Refer to Pressure Cap Testing .
- Ensure that the coolant level is correct.
- Install the coolant filler neck adapter to commercially available cooling system pressure tester.
- Install the assembly to the engine coolant filler neck.
- Using compressed air, blow dry any spilled coolant around coolant filler neck.
- Using the cooling system pressure tester pump, pressurize the cooling system to 150 kPa (22 psi) absolute maximum and check for leaks at the following points:
- All hose and hose connections.
- Overflow hose connection at coolant outlet housing connection.
- Radiator seams and core.
- Corroded or damaged engine core plugs.
- Water pump and gasket.
- Thermostat housing and inlet pipe connection.
- Radiator drain cock.
- Vehicle heating system (e.g. heater core and water valve).
- Check engine oil dipstick for evidence of engine oil contamination with the coolant.
- Repair any leaks as required.
- If pressure will not hold, there is a leak in the cooling system. Repair as necessary.
Make sure not to exceed the stated pressure.
If a visible loss of coolant is not evident from pressure testing, the use of dye and black light testing will aid in locating the leak.
Black Light and Dye Leak Diagnosis Method
- Remove the pressure cap.
- Pour a specified amount of dye into the cooling system.
- Road test the vehicle under normal operating conditions.
- Direct the black light towards the suspect area. Any fluid leak will appear as a bright colored path leading to the source.
- Repair the fluid leak and carry out a second road test to ensure the leak has been rectified.
- Refer to the manufacture's direction when preforming this method.
Under pressure, the temperature of the solution in the radiator can be considerably higher, without boiling. Removing the radiator cap while the engine is hot (pressure is high), will cause the solution to boil instantaneously, with explosive force. The solution will spew out over the engine, fenders, and the person removing the cap. Serious bodily injury may result. Flammable antifreeze, such as alcohol, is not recommended for use at any time. Flammable antifreeze could cause a serious fire.
In order to help avoid being burned, do not remove the radiator cap while the engine and the radiator are hot. Scalding fluid and steam can be blown out under pressure if the cap is removed too soon.
Adding dye to the cooling system, may change the color of the coolant to a dark, muddy green. As the use of extended life anti-freeze coolant (conforming to GM6277M) to this cooling system is mandatory and should not be mixed with other composition coolants, the green color could be misleading for future top-up operations. Therefore, should the coolant change color when the leak detection dye is added, then the cooling system must be drained and new extended life anti-freeze coolant (conforming to GM6277M) coolant added. Refer to Cooling System Draining and Filling .