Combustion Leakage Test - Without Pressure Tester
Do not remove cylinder block drain plugs or loosen radiator draincock with system hot and under pressure. Serious burns from coolant can occur.
DO NOT WASTE reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse.
Drain sufficient coolant to allow thermostat removal. Refer to COOLING/STANDARD PROCEDURE or THERMOSTAT, REMOVAL . Remove serpentine belt. Refer to BELT, SERPENTINE, REMOVAL .
Add coolant to radiator to bring level to within 6.3 mm (1/4 in) of the top of the thermostat housing.
Avoid overheating. Do not operate engine for an excessive period of time. Open draincock immediately after test to eliminate boil over.
Start engine and accelerate rapidly three times, to approximately 3000 rpm while observing coolant. If internal engine combustion gases are leaking into cooling system, bubbles will appear in the coolant. If bubbles do not appear, internal combustion gas leakage is not present.