Coolant Heater Diagnosis (Exhaust Leaks and Noise)
EXHAUST LEAKS1. Drain only enough coolant so that the level is just above the top of the cylinder head.
2. Disconnect the radiator inlet (upper) hose.
3. Remove the coolant thermostat.
NOTICE: Allowing the drive belt tensioner to snap into the free position may result in damage to the tensioner.
4. Remove the accessory drive belt..
5. Start the engine. Increase the engine speed (RPM) several times, while observing the coolant level. Any noticeable rise in the coolant level or the appearance of bubbles may show that exhaust gas is leaking into the cooling system.
NOISE
Cooling system noise can be caused by restrictions to coolant flow. This can cause the coolant to boil at some localized point. Symptoms usually appear after extended idling or driving. Possible symptoms are:
^ The engine may make snapping or cracking noises.
^ The radiator hoses may expand or collapse.
^ The coolant heater hoses may vibrate or thump.
^ The coolant heater core may gurgle or surge.
^ The engine overheat lamp may or may not be illuminated.
Use the following procedure to remove any restrictions in coolant flow.
1. Backflush the cooling system, then retest.
2. Use a mechanic's stethoscope to determine what areas are still affected.
3. Disassemble suspect components for further inspection and cleaning, as necessary.