Pinpoint Tests: Notes

Loss of Coolant 

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)
• Radiator
• Pressure relief cap
• Coolant pump leaking from weep hole
• Heater core
• Lower intake manifold
• Engine gaskets (may leak internally or externally)
• Degas bottle
• Cylinder block core plugs
• Cylinder head core plugs
• Block heater (if equipped)