Pinpoint Test B: The Cooling System Overheats

Powertrain Secondary Cooling System

Pinpoint Test B: The Cooling System Overheats

Normal Operation

The secondary cooling system maintains temperatures in the Charge Air Cooler (CAC), the fuel cooler, the transmission cooler and the EGR cooler during operation. Correct coolant flow through the radiator and the remaining components of the system is essential to maintaining correct temperatures.

Coolant flows primarily from the coolant pump to the radiator circuit and then to the transmission fluid cooler and EGR cooler from the high temperature thermostat and the CAC (Charge Air Cooler) and the fuel cooler from the low temperature thermostat. The coolant flows from each component to the degas bottle and then back to the coolant pump. 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 thermostats are control valves actuated by coolant temperature. When the thermostats are closed, coolant flow bypasses the radiator circuit and flows to the 4 cooling components. When the thermostats are opened, coolant is allowed to flow through the radiator circuit in order to transfer component-generated heat to the outside air.

System overheating generally occurs when there is a disruption in the ability to control either coolant flow at the proper rate, the inability to transfer heat from the cooling components through the coolant (including low coolant) or an inability to transfer component-generated heat to the outside air through the radiator.

- DTC P007D (CACT (Charge Air Cooler Temperature) Sensor Circuit High)- Indicates a higher than expected air temperature as the air flows out of the CAC (Charge Air Cooler).

- DTC P2185 (Engine Coolant Temperature (ECT) Sensor 2 Circuit High)- Indicates higher than expected coolant temperature as the coolant flows into the EGR cooler.

This pinpoint test is intended to diagnose the following:

- Low coolant level

- External engine coolant leak

- Airlock in system

- Pressure relief cap installation

- Restricted airflow through the A/C condenser or radiator

- Internal coolant leak

- Coolant condition/concentration

- Accessory drive components

- Non-OEM engine enhancement components

- Thermostats

- ECT (Engine Coolant Temperature) sensor - secondary cooling system ECT (Engine Coolant Temperature) 2

- Charge Air Cooler Temperature (CACT) sensor

- Coolant pump

- Coolant flow restriction

PINPOINT TEST B : THE SYSTEM OVERHEATS

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.

B1 CARRY OUT INSPECTION AND VERIFICATION

- Carry out the Inspection and Verification procedure. Inspection and Verification

Were any concerns found?

Yes
REPAIR as needed. TEST the system for normal operation.

No
GO to B2.

B2 CHECK FOR PCM DTCs

- Check for PCM DTCs P007D or P2185.

Is DTC P007D or P2185 present?

Yes
GO to B3.

No
Actual system overheating has not been verified. If any other PCM DTCs are retrieved, REFER to the Computers and Control Systems.

B3 CHECK FOR NON-OEM ENGINE ENHANCEMENT COMPONENTS

- Check the engine for any non-OEM components.

Are there any non-OEM components on the engine?

Yes
ADVISE the customer the engine modifications may be causing the secondary cooling system to overheat.

No
GO to B4.

B4 CHECK FOR AN AIRFLOW OBSTRUCTION

- Check the radiator or A/C condenser for an obstruction such as leaves or cardboard.

Is an obstruction present?

Yes
REMOVE the obstruction. TEST the system for normal operation.

No
GO to B5.

B5 CHECK THE ENGINE COOLANT LEVEL

NOTE: Allow the engine to cool before checking the coolant level.

- Ignition OFF.

- Visually check the system coolant level in the degas bottle.

Is the coolant level within specification?

Yes
GO to B6.

No
ADJUST the coolant level as necessary. GO to B6.

B6 PRESSURE TEST THE COOLING SYSTEM

- Pressure test the cooling system. Refer to Component Tests, Cooling System Pressure Test. Powertrain Secondary Cooling System

Does the cooling system leak?

Yes
REPAIR or INSTALL new components. TEST the system for normal operation.

No
GO to B7.

B7 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK

- Inspect the engine coolant in the degas bottle for signs of fuel or transmission fluid.

Is fuel or transmission fluid evident in the coolant?

Yes
If fuel is evident, INSTALL a new fuel cooler. If transmission fluid is evident, INSTALL a new transmission fluid cooler. REPAIR the transmission as necessary. TEST the system for normal operation.

No
GO to B8.

B8 CHECK THE FUEL AND TRANSMISSION FLUID FOR COOLANT

- Drain the fuel from the fuel conditioning module. Remove the oil level indicator from transmission.

Is coolant evident in the fuel or transmission fluid?

Yes
If coolant is in the fuel, INSTALL a new fuel cooler. If coolant is in the transmission fluid, INSTALL a new transmission fluid cooler. REPAIR the transmission as necessary. TEST the system for normal operation.

No
GO to B9.

B9 CHECK THE Charge Air Cooler (CAC)
FOR AN INTERNAL LEAK

- Carry out the CAC (Charge Air Cooler) leak test. REFER to Fuel Delivery and Air Induction.

Does the CAC (Charge Air Cooler) leak?

Yes
INSTALL a new CAC (Charge Air Cooler). TEST the system for normal operation.

No
GO to B10.

B10 CHECK THE EGR COOLER FOR AN INTERNAL LEAK

- CARRY OUT the EGR cooler leak test. REFER to Emission Control Systems.

Does the EGR cooler leak?

Yes
REPAIR the EGR cooler as necessary. TEST the system for normal operation.

No
GO to B11.

B11 CHECK COOLANT CONDITION

- Carry out the coolant test. Refer to Coolant Test .

Is the coolant condition OK?

Yes
GO to B12.

No
FLUSH the cooling system. REFER to Cooling System Flushing - Without Fuel or Transmission Fluid Contamination . TEST the system for normal operation.

B12 CHECK THE COOLANT PUMP OPERATION

- Start the engine.

- Observe the coolant in the degas bottle. The coolant should flow through the bottle. Compare the coolant flow to a known good vehicle.

Does the coolant flow through the degas bottle?

Yes
GO to B13.

No
INSTALL a new coolant pump. TEST the system for normal operation.

B13 CHECK THE THERMOSTAT OPERATION

- Start the engine.

- For DTC P007D, allow the engine to run for 10 minutes. Feel the coolant pump-to-radiator hose at the LH inlet, and the radiator-to-CAC (Charge Air Cooler) and fuel cooler hose.

- For DTC P2185, allow the engine to run for 10 minutes. Feel the coolant pump-to-radiator hose at the RH inlet, the radiator-to-transmission fluid cooler hose and the radiator-to-EGR cooler hose.

Are the hoses approximately the same temperature?

Yes
GO to B14.

No
The system is operational. CHECK the operation of the CACT (Charge Air Cooler Temperature) sensor and the ECT (Engine Coolant Temperature) sensor - secondary cooling system ECT (Engine Coolant Temperature) 2. REFER to Computers and Control Systems Information.

B14 VISUALLY INSPECT THE THERMOSTAT

- Carry out the Thermostat Visual Inspection in the Component Tests.

Is the thermostat damaged?

Yes
INSTALL a new thermostat. TEST the system for normal operation.

No
INSTALL a new thermostat. TEST the system for normal operation. If the engine still overheats, GO to B15.

B15 CHECK THE COOLING FAN CLUTCH OPERATION

- Ignition OFF.

- Check the cooling fan clutch operation. Refer to Computers and Control Systems Information.

Is the cooling fan clutch operation OK?

Yes
INSTALL a new radiator. TEST the system for normal operation.

No
INSTALL a new fan clutch. TEST the system for normal operation.