Pinpoint Test A: Loss Of Coolant
WARNING: This page is about a different variant/trim than selected.
- Normal Operation and Fault Conditions
The engine cooling system is a closed system providing for coolant expansion and contraction as well as changes in pressure as coolant warms and cools with engine operation. Various gaskets, seals, hoses and clamps contain coolant within the cooling system and keep other fluids and contaminants from entering the cooling system.
Possible Sources
- Coolant hoses or tubes
- Hose clamps
- Thermostat O-ring seal or gasket
- Coolant pump O-ring seal or gasket
- Thermostat housing
- Oil cooler (may leak internally or externally) (if equipped)
- Transmission fluid warmer (may leak internally or externally)
- Transmission fluid heater coolant control valve
- Radiator
- Pressure relief cap
- Coolant pump leaking from weep hole
- Cabin heater coolant pump
- Heater core
- Lower intake manifold
- Engine gaskets (may leak internally or externally)
- Degas bottle
- Cylinder block core plugs
- Cylinder head core plugs
- Block heater
- WARNING: Always allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
- A1 CARRY OUT INSPECTION AND VERIFICATION
- Carry out Inspection and Verification.
Are any concerns present?
Yes REPAIR as needed. No GO to A2 - A2 CHECK THE ENGINE COOLANT LEVEL AND PRESSURE TEST THE ENGINE COOLING SYSTEMNOTE: Allow the engine to cool before checking the engine coolant level.
- Ignition OFF
- Visually inspect the engine coolant level at the degas bottle and adjust as necessary. Pressure test the engine cooling system. Refer to Cooling System Pressure Test .
Does the engine cooling system leak externally?
Yes REPAIR or INSTALL new components. No GO to A3 - A3 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK
- Inspect the engine coolant in the degas bottle for signs of engine oil.
Is engine oil evident in the engine coolant?
Yes REFER to: Engine . No GO to A4 - A4 CHECK THE ENGINE OIL FOR COOLANT
- Remove the oil level indicator from the engine.
Is coolant evident in the oil?
Yes REFER to: Engine . No GO to A5 - A5 CHECK THE ENGINE COOLANT FOR TRANSMISSION FLUID
- Check the engine coolant in the degas bottle for signs of transmission fluid.
Is transmission fluid evident in the engine coolant?
Yes INSTALL a new transmission fluid warmer. REFER to: Transmission Fluid Cooler . REPAIR the transmission as necessary. REFER to: Diagnosis By Symptom . TEST the system for normal operation. No GO to A6 - A6 CHECK THE TRANSMISSION FLUID FOR ENGINE COOLANT
- Remove the transmission oil leveling plug.
- Check the transmission fluid for engine coolant.
Is engine coolant evident in the transmission fluid?
Yes INSTALL a new transmission fluid warmer. REFER to: Transmission Fluid Cooler . REPAIR the transmission as necessary. REFER to: Diagnosis By Symptom . TEST the system for normal operation. No GO to A7 - A7 CHECK THE COOLING SYSTEM FOR COMBUSTION GASESNOTE: Use UView® Combustion Leak Tester part number UVU560000-R 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?
Yes REFER to: Engine . No The cooling system is operational