Combustion Leakage Test (Without Pressure Tester)
DO NOT WASTE reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse.
Do not remove the cylinder block drain plugs or loosen the radiator draincock with the system hot and under pressure. Serious burns from coolant can occur.
Remove thermostat. Refer to THERMOSTAT, REMOVAL .
Remove accessory drive belt. Refer to BELT, SERPENTINE, REMOVAL .
Add coolant to the radiator to bring the level to within 6.3 mm (1/4 in) of the top of the thermostat housing.
Avoid overheating. Do not operate the engine for an excessive period of time. Open the draincock immediately after the test to eliminate boil over of coolant.
Start the engine and accelerate rapidly three times (to approximately 3000 RPM) while observing the coolant. If internal engine combustion gases are leaking into the cooling system, bubbles will appear in the coolant. If bubbles do not appear, there is no internal combustion gas leakage.