Engine Overheating. Cadillac CTS 2004

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2004 🢒 CTS 🢒 Engine 🢒 Engine Controls - 3.6L (LY7) 🢒 Engine Overheating

Engine Overheating LA3, LY9

Diagnostic Aids

The engine may overheat due to an intermittent operation of one of the following components:

•	The after boil heater pump

•	The coolant bypass solenoid

•	The coolant bypass valve

•	The electric cooling fans

•	The thermostat

For electrical inspection of the cooling fans and the after boil heater pump, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

Value(s)

Yes

DEFINITION: Engine temperature lamp comes ON and stays ON, or the temperature gage shows hot, or coolant overflows from the surge tank onto the ground while the engine is running.

Did you perform the engine cooling diagnostic system check?

Go to Step 2

Go to Diagnostic System Check - Engine Cooling

Inspect the surge tank for low coolant.

Is there a loss of coolant?

Go to Loss of Coolant

Go to Step 3

Important: Do not allow the engine temperature to exceed the specified value.

Start the engine and allow to reach normal operating temperature.

Does the engine begin to exceed the specified value?

107°C (225°F)

Go to Step 4

Go to Diagnostic Aids

Inspect for loose, damaged, and/or missing of the following:

•	The A/C condenser seals

•	The front air deflector

•	The side seals

Repair the system as necessary.

Does the engine still overheat?

Go to Step 5

Go to Step 18

Using the J 23688 Coolant and Battery Fluid Tester, test for insufficient coolant concentration.

Is the coolant protection greater than the specified value?

-37°C (-34°F)

Go to Step 6

Go to Step 7

Correct the coolant concentration as necessary.

Does the engine still overheat?

Go to Step 7

Go to Step 18

Inspect for obstructed radiator air flow or bent radiator fins.

Is the radiator air flow obstructed?

Go to Step 8

Go to Step 9

Clean the radiator. Refer to Radiator Cleaning .

Does the engine still overheat?

Go to Step 9

Go to Step 18

Inspect the drive belt tensioner. Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical-2.6L and 3.2L.

Is the drive belt tensioner working properly and is the tension correct?

Go to Step 11

Go to Step 10

Replace the drive belt tensioner. Refer to Drive Belt Tensioner Replacement in Engine Mechanical-2.6L and 3.2L.

Does the engine still overheat?

Go to Step 11

Go to Step 18

Inspect the thermostat for proper operation. Refer to Thermostat Diagnosis .

Does the thermostat operate properly?

Go to Step 13

Go to Step 12

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Does the engine still overheat?

Go to Step 13

Go to Step 18

Inspect for a inoperative after boil coolant pump. Refer to After Boil Coolant Pump Inoperative .

Does the engine still overheat?

Go to Step 14

Go to Step 18

Inspect for an inoperative cooling fan. Refer to Cooling Fan Inoperative or Cooling Fan Inoperative - Auxiliary .

Does the engine still overheat?

Go to Step 15

Go to Step 18

Inspect for blocked cooling system passages.

Are the cooling system passages blocked?

Go to Step 16

Go to Step 17

Replace the radiator. Refer to Radiator Replacement .

Does the engine still overheat?

Go to Step 17

Go to Step 18

Replace the engine water pump. Refer to Water Pump Replacement .

Did you complete the repair?

Go to Step 18

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2

Engine Overheating LY7

Step

Action

Yes

DEFINITION: Either of the following conditions indicate a probable engine overheat condition.

•	The engine temperature gage is in the red (overheat) zone and/or the engine temperature indicator is ON.

•	Hot engine coolant overflows from the coolant recovery reservoir and/or radiator cap onto the ground while the engine is running.

Inspect and fill the cooling system, as necessary. Refer to Cooling System Draining and Filling .
Inspect the cooling system for leaks, as necessary.
Repair the cooling system leaks, as necessary.

Has the inspection/repair been performed?

Go to Step 2

Start the engine and allow the engine to run at approximately 1,200 RPM.
Use the Scan Tool in order to verify the overheat condition.

Does the Scan Tool verify the engine overheat condition?

Go to Step 3

Go to Diagnostic System Check - Driver Information Systems in Instrument Panel, Gauges and Console

Verify that the cooling fans are operating properly.
Repair the cooling fan system, as necessary.

Does the engine still overheat?

Go to Step 4

System OK

Perform the following inspections:

•	Inspect the radiator and the A/C condenser cooling fins for debris or any other obstruction.

•	Inspect the drive belt system and the drive belt tensioner for proper operation in order to ensure that the coolant pump is rotating properly. Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical - 3.6L(LY7).

•	Inspect for loose, damaged and/or missing air deflector(s).

•	Check for a pinched or kinked cooling system hose.

•	Repair the systems as necessary.

Does the engine still overheat?

Go to Step 5

System OK

Inspect the thermostat for proper operation. Refer to Thermostat Diagnosis .

Is the thermostat operating properly?

Go to Step 7

Go to Step 6

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Does the engine still overheat?

Go to Step 7

System OK

Important: Excessive coolant freeze point protection MAY cause the coolant to boil at low temperatures.

Inspect for the proper coolant concentration (mixture). Correct the coolant concentration as necessary.
Remove the radiator cap.
Start the engine and inspect for a constant flow of air bubbles in the engine coolant.

Is there a constant flow of air bubbles in the engine coolant?

Go to Step 8

Go to Step 9

The probable cause of the engine overheat is combustion chamber gasses leaking into the cooling system. This condition is usually caused by the following:

•	A worn or damaged cylinder head gasket

•	A worn or damaged cylinder head

•	A worn and/or damaged engine block

Verify this condition by inspecting the spark plug electrodes and porcelain surrounding the spark plug electrode for signs of coolant. Replace and/or repair the engine internal component(s), as necessary, in order to repair the engine internal coolant leak.

Does the engine still overheat?

Go to Step 1

System OK

The engine overheat may be caused by a cooling system blockage. Flush the cooling system. Refer to Flushing .

Does the engine still overheat?

Go to Step 10

System OK

Important: It is unlikely that the water pump is the cause of the overheat condition.

If NONE of the cooling system passages are restricted, replace the coolant pump. Refer to Water Pump Replacement .

Does the engine still overheat?

Go to Step 1

System OK

Engine Overheating LS6

Step

Action

Yes

DEFINITION: Either of the following conditions indicate a probable engine overheat condition.

•	The engine temperature gage is in the red (overheat) zone and/or the engine temperature indicator is ON.

•	Hot engine coolant overflows from the coolant recovery reservoir and/or radiator cap onto the ground while the engine is running.

Inspect and fill the cooling system, as necessary. Refer to Cooling System Draining and Filling .
Inspect the cooling system for leaks, as necessary.
Repair the cooling system leaks, as necessary.

Has the inspection/repair been performed?

Go to Step 2

Start the engine and allow the engine to run at approximately 1,200 RPM.
Use the Scan Tool in order to verify the overheat condition.

Does the Scan Tool verify the engine overheat condition?

Go to Step 3

Go to Diagnostic System Check - Driver Information Systems in Instrument Panel, Gages, and Console

Verify that the cooling fans are operating properly.
Repair the cooling fan system, as necessary.

Does the engine still overheat?

Go to Step 4

System OK

Perform the following inspections:

•	Inspect the radiator and the air conditioning (A/C) condenser cooling fins for debris or any other obstruction.

•	Inspect the drive belt system and the drive belt tensioner for proper operation in order to ensure that the coolant pump is rotating properly. Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical - 5.7L.

•	Inspect for loose, damaged and/or missing air deflector(s).

•	Inspect for a pinched or kinked cooling system hose.

•	Repair the systems as necessary.

Does the engine still overheat?

Go to Step 5

System OK

Inspect the thermostat for proper operation. Refer to Thermostat Diagnosis .

Is the thermostat operating properly?

Go to Step 7

Go to Step 6

Replace the thermostat. Refer to Engine Coolant Thermostat Replacement .

Does the engine still overheat?

Go to Step 7

System OK

Important: Excessive coolant freeze point protection MAY cause the coolant to boil at low temperatures.

Inspect for the proper coolant concentration (mixture). Correct the coolant concentration as necessary.
Remove the radiator cap.
Start the engine and inspect for a constant flow of air bubbles in the engine coolant.

Is there a constant flow of air bubbles in the engine coolant?

Go to Step 8

Go to Step 9

The probable cause of the engine overheat is combustion chamber gasses leaking into the cooling system. This condition is usually caused by the following:

•	A worn or damaged cylinder head gasket

•	A worn or damaged cylinder head

•	A worn and/or damaged engine block

Does the engine still overheat?

Go to Step 1

System OK

The engine overheat may be caused by a cooling system blockage. Flush the cooling system. Refer to Flushing .

Does the engine still overheat?

Go to Step 10

System OK

Important: It is unlikely that the water pump is the cause of the overheat condition.

If NONE of the cooling system passages are restricted, replace the coolant pump. Refer to Water Pump Replacement .

Does the engine still overheat?

Go to Step 1

System OK