Pinpoint Test A: Loss of Coolant

Normal Operation 

The engine cooling system is a closed system that provides for coolant expansion and contraction and also changes in pressure as coolant warms and cools with engine operation. Various gaskets, seals, hoses and clamps are used to contain coolant within the cooling system and keep other fluids and contaminants from entering the cooling system.

Coolant loss can be attributed to either external or internal leaks anywhere within the cooling system.

For vehicle/engine specific information, refer to Engine Cooling .

This pinpoint test is intended to diagnose the following:

• Coolant hoses or tubes
• Hose clamps
• Thermostat O-ring seal or gasket
• Coolant pump O-ring seal or gasket
• Thermostat housing
• Heater control valve (if equipped)
• Radiator
• Transmission fluid cooler (in radiator) (if equipped)
• Pressure relief cap
• Coolant pump leaking from weep hole
• Auxiliary coolant pump (if equipped)
• Heater core
• Heated throttle body (TB) or heated TB adapter (if equipped)
• Coolant crossover manifold assembly (if equipped)
• Engine gaskets
• Oil cooler (if equipped)
• Degas bottle (if equipped)
• Coolant expansion tank (if equipped)
• Heated PCV (if equipped)
• Fuel pressure regulator coolant bowl (if equipped, natural gas engine)
• Cylinder block core plugs (if equipped)
• Cylinder head core plugs (if equipped)
• Block heater (if equipped)
• Engine coolant temperature (ECT) sensor (if equipped)

PINPOINT TEST A: LOSS OF COOLANT 

1. A1 CARRY OUT INSPECTION AND VERIFICATION 
   • Carry out the Inspection & Verification .
   • Were any concerns found? 
   1. YES  : REPAIR as needed. TEST the system for normal operation.
   2. NO  : Go to  A2.
2. A2 CHECK THE ENGINE COOLANT LEVEL 
   NOTE: Allow the engine to cool before checking the engine coolant level.
   • Key in OFF position.
   • Visually inspect the engine coolant level at the degas bottle or the coolant expansion tank.
   • Is the engine coolant level within specifications? 
   1. YES  : Go to  A3.
   2. NO  : ADJUST the engine coolant level as necessary. Go to  A3.
3. A3 PRESSURE TEST THE ENGINE COOLING SYSTEM 
   • Pressure test the engine cooling system. Refer to Component Tests .
   • Does the engine cooling system leak? 
   1. YES  : REPAIR or INSTALL new components. TEST the system for normal operation.
   2. NO  : If the vehicle is equipped with a coolant expansion tank, go to  A4. If the vehicle is equipped with a degas bottle, go to  A5.
4. A4 CHECK THE PRESSURE RELIEF CAP 
   • Carry out the pressure relief cap pressure test. Refer to Component Tests .
   • Is the pressure relief cap OK? 
   1. YES  : Go to  A5.
   2. NO  : INSTALL a new pressure relief cap. TEST the system for normal operation.
5. A5 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK 
   • Inspect the engine coolant in the degas bottle or coolant expansion tank for signs of engine oil or transmission fluid.
   • Is engine oil or transmission fluid evident in the coolant? 
   1. YES  : If engine oil is evident, go to ENGINE SYSTEM - GENERAL INFORMATION article for engine diagnosis. If transmission fluid is evident, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate Automatic Transmission article for the procedure. TEST the system for normal operation.
   2. NO  : Go to  A6.
6. A6 CHECK THE ENGINE OIL AND TRANSMISSION FLUID FOR COOLANT 
   • Remove the oil level indicators from the engine and the transmission.
   • Is coolant evident in the oil or transmission fluid? 
   1. YES  : If coolant is in the engine oil, go to ENGINE SYSTEM - GENERAL INFORMATION article. If coolant is in the transmission fluid, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate Automatic Transmission article for the procedure.
   2. NO  : Go to  A7.
7. A7 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES 
   NOTE: Use U-View® Combustion Leak Tester part number 560000 or equivalent.
   • Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases.
   • Are combustion gases present? 
   1. YES  : Go to ENGINE SYSTEM - GENERAL INFORMATION article for engine diagnosis.
   2. NO  : The cooling system is operational.