Pinpoint Test C: The Engine Does Not Reach Normal Operating Temperature
Engine Cooling
Pinpoint Test C: The Engine Does Not Reach Normal Operating Temperature
Normal Operation
The engine cooling system functions to maintain engine temperatures during operation. Proper coolant flow through the engine, radiator and remainder of cooling system passages and components is essential to maintaining a proper engine temperature.
Engine coolant flows primarily from the engine to the radiator circuit and back to the coolant pump. From the coolant pump, coolant is sent through the engine block and cylinder heads. A separate circuit from the engine also feeds the heater core with coolant. The coolant pump is operated by engine rotation through a pulley which is driven by the accessory drive belt to circulate the coolant. The coolant thermostat is a control valve actuated by coolant temperature. When the thermostat is closed, coolant flow bypasses the radiator circuit and returns to the coolant pump. When the thermostat is opened, coolant is allowed to flow through the radiator circuit in order to transfer engine generated heat to the outside air.
Concerns of engine inability to reach normal operating temperature typically occur when the rate of coolant flow through some coolant circuits (radiator, heater core) is more than expected given the conditions or the fan clutch is always engaged. Heat is not allowed to build in the engine because a heat exchanger is removing too much heat, including the radiator and heater core. In addition, perceived concerns that the engine does not reach normal operating temperature can be related to a low coolant level or trapped air which does not allow for hot coolant to be available at the heater core, an inoperative climate control system, or for concerns perceived or related to an incorrect engine temperature gauge indication.
- DTC P0125 Insufficient Coolant Temperature For Closed Loop Fuel Control
- DTC P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
This pinpoint test is intended to diagnose the following:
- Low coolant level
- Thermostat
- Engine Coolant Temperature (ECT) indicator system (gauge)
- Engine cooling fan
PINPOINT TEST C: THE ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURE
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.
