Low Coolant Level - Symptoms and Causes

Description and Causes

Low coolant level in a cross flow radiator will equalize in both tanks with engine off. With engine at running operating temperature the high pressure inlet tank runs full and the low pressure outlet tank drops.
^ High reading shown on the temperature gauge.
^ Air in the coolant will also cause loss of flow through the heater core.
^ Exhaust gas leaks into the coolant can also cause the same problems.