Cooling System: Notes

Establish what driving condition caused the cooling system complaint. The problem may be caused by an abnormal load on the system such as the following: prolonged idle, very high ambient temperature, slight tail wind at idle, slow traffic speed, traffic jam, high speed or steep grade.

COOLING SYSTEM DIAGNOSIS CHART

CONDITION	POSSIBLE CAUSES	CORRECTION
PRESSURE CAP IS BLOWING OFF STEAM AND/OR COOLANT. TEMPERATURE GAUGE READING MAY BE ABOVE NORMAL BUT NOT HIGH.	1. Pressure relief valve in pressure cap is defective, or was not properly seated.	1. Check condition of pressure cap and cap seal. Replace cap as necessary.
	2. Incorrect pressure cap was installed.	2. Replace pressure cap as necessary.
	3. Incorrect coolant mixture.	3. Fill with correct coolant. Refer to CAPACITIES AND RECOMMENDED FLUIDS .
COOLANT LOSS TO THE GROUND WITHOUT PRESSURE CAP BLOWOFF. GAUGE IS READING HIGH OR HOT.	1. Coolant leaks in radiator, cooling system hoses, water pump or engine.	1. Pressure test cooling system and repair as necessary.
DETONATION OR PRE-IGNITION (NOT CAUSED BY IGNITION SYSTEM). GAUGE MAY NOT BE READING HIGH.	1. Engine overheating.	1. Check reason for overheating and repair as necessary.
	2. Freeze point of coolant not correct. Mixture too concentrated or too diluted.	2. Check freeze point of the coolant. Adjust the ethylene glycol-to-water ratio as required.
	3. Wrong cooling system pressure cap.	3. Install correct pressure cap.
HOSE(S) COLLAPSE AS ENGINE COOLS DOWN.	1. Vacuum created in cooling system on engine cool-down is not being relieved through coolant bottle system.	1. Pressure cap relief valve stuck. Replace as necessary.
INADEQUATE AIR CONDITIONER PERFORMANCE (COOLING SYSTEM SUSPECTED).	1. Radiator and/or A/C condenser is restricted, obstructed, or dirty (insects, leaves, etc.).	1. Remove restriction and/or clean as necessary.
	2. Engine is overheating (heat may be transferred from radiator to A/C condenser). High underhood temperatures due to engine overheating may also transfer heat to A/C components.	2. Correct overheating condition.
INADEQUATE HEATER PERFORMANCE.	1. Has a diagnostic trouble code (DTC) been set?	1. Refer to the appropriate Powertrain Diagnostic information. Repair as necessary.
	2. Coolant level low.	2. Adjust coolant level as necessary. Check cooling system for leaks. Repair as necessary.
	3. Obstructions in heater hose fitting at engine or at heater core.	3. Remove heater hoses at both ends and check for obstructions. Repair as necessary.
	4. Heater hose kinked.	4. Locate kinked area and repair as necessary.
	5. Water pump is not pumping coolant to heater core. When the engine is fully warmed up, both heater hoses should be hot to the touch. If only one of the hoses is hot, the water pump may not be operating correctly.	5. Replace water pump.
HEAT ODOR.	1. Various heat shields are used at certain driveline components. One or more of these shields may be missing.	1. Locate missing shields and replace or repair as necessary.
	2. Is temperature gauge reading above the normal range?	2. Refer to Gauge Is Reading High in these Diagnosis Charts.
	3. Is cooling fan operating correctly?	3. Refer to appropriate Diagnostic Information. Repair as necessary.
	4. Has undercoating been applied to any unnecessary component?	4. Clean undercoating as necessary.
	5. Engine may be running rich, causing the catalytic converter to overheat.	5. Refer to appropriate Diagnostic Information for operation of the scan tool. Repair as necessary.
POOR DRIVEABILITY (THERMOSTAT STUCK OPEN). GAUGE MAY BE READING LOW.	1. The engine thermostat must be operating correctly for proper driveability, clean vehicle emissions, and the prevention of sludge buildup in the engine oil. Has a diagnostic trouble code been set?	1. Refer to appropriate Diagnostic Information for operation of the Scan Tool. Replace thermostat, if necessary.
STEAM IS COMING FROM FRONT OF VEHICLE NEAR GRILL AREA WHEN WEATHER IS WET, ENGINE WARMED UP AND RUNNING WITH VEHICLE STATIONARY, OR JUST SHUT OFF. TEMPERATURE GAUGE IS NORMAL.	1. During wet weather, moisture (snow, ice, rain, or condensation) on the radiator will evaporate when the thermostat opens. The thermostat opening allows heated coolant into the radiator. When the moisture contacts the hot radiator, steam may be emitted. This usually occurs in cold weather with no fan or air flow to blow it away.	1. Occasional steam emitting from this area is normal. No repair is necessary.
COOLANT COLOR.	1. Coolant color is not necessarily an indication of adequate corrosion or temperature protection. Do not rely on coolant color for determining condition of coolant.	1. Check the freeze point of the coolant. Refer to COOLANT, DIAGNOSIS AND TESTING . Adjust the ethylene glycol-to-water ratio as necessary.
COOLANT LEVEL CHANGES IN COOLANT BOTTLE. TEMPERATURE GAUGE IS IN NORMAL RANGE.	1. Level changes are to be expected as coolant volume fluctuates with engine temperature. The coolant level will also drop as the system removes air from a recent filling.	1. A normal condition. No repair is necessary.

TEMPERATURE GAUGE INDICATION DIAGNOSIS CHART

CONDITION	POSSIBLE CAUSES	CORRECTION
TEMPERATURE GAUGE READING IS INCONSISTENT (FLUCTUATES, CYCLES OR IS ERRATIC).	1. Normal reaction to fan and/or thermostat cycle, Examples B and C. During cold weather operation with the heater blower in the high position, the gauge reading may drop slightly, Example D. Fluctuation is also influenced by outside temperature and heavy loads, Example E.	1. A normal condition. No correction is necessary.
	2. Gauge reading rise when vehicle is brought to a stop after heavy use (engine still running), Example F.	2. A normal condition. No correction is necessary. Gauge reading should return to normal range, Example A, after vehicle is driven.
	3. Gauge reading high after restarting a warmed-up (hot) engine.	3. A normal condition. No correction is necessary. The gauge should return to normal range, Example A, after a few minutes of engine operation.
	4. Temperature gauge or engine sending unit sensor defective or shorted. Also, corroded or loose wiring in this circuit.	4. Check operation of gauge and repair if necessary. Refer to INSTRUMENT PANEL/GAUGES.

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