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Cooling System Troubleshooting (All Models): Troubleshooting

COOLING SYSTEM TROUBLESHOOTING (ALL MODELS)

CONDITION CAUSE
Engine over heats with no coolant loss.  Coolant level low. Thermostat stuck closed or partially closed. Fan clutch not working. Water distribution tube clogged. Radiator air flow passages blocked by debris.
Engine over heats with external coolant loss.  Broken or slipping fan belt. Thermostat stuck closed or partially closed. Water pump shaft broken. Leaking freeze plugs. Fan clutch not operating. Defective radiator cap. Water distribution tube clogged.
Engine fails to reach normal operating temperature.  Thermostat stuck in open position. Temperature gauge or light may be defective indicating normal operating temperature.
Engine over heats with internal coolant leakage.  Cracked intake manifold, blown head gaskets or warped head or engine block. Cracked cylinder head or engine block.
Excessive foaming in radiator.  Improper ratio of water to coolant. System must be flushed.
Poor circulation of coolant.  Check top of radiator tubes visually for evidence of plugged or restricted radiator. Check for restriction in cylinder heads or engine block for internal clogging. Check for collapsed lower radiator hose.