Engine Overheating Causes
Preliminary Diagnosis
- Does overheating occur while pulling a trailer?
- Is overheating occurring after prolonged idle in gear, A/C system operating?
- Is overheating occurring after prolonged driving in slow city traffic, traffic jams, parades, etc.?
Is the trailer within the recommended towing weight?
If none of the above apply refer to the table below.
Possible Cause | Correction |
|---|---|
Coolant fan inoperative | Refer to cooling fan Diagnosis |
Thermostat stuck in closed position | Replace the thermostat. Refer to Engine Coolant Thermostat Replacement |
Radiator fins obstructed | Remove or relocate add-on parts that block air to the radiator. Clean away bugs, leaves, etc. In cold climates, clear away snow, etc. from the radiator core. |
Surge tank outlet hose pinched or kinked (especially at radiator) | Relieve kinks by re-routing. Replace the hose if necessary. |
Incorrect radiator | Check the radiator usage chart in a parts catalog. If needed, replace with the correct radiator. |
Loss of system pressure | Pressure check system and surge tank cap. Refer to Cooling System Leak Testing Ensure the correct cap is being used. |
Loose, damaged and or missing air seals or deflector | Repair or replace as required. |
Cooling system passages blocked | Remove the obstruction. Flush the cooling system as required and refill with coolant. |
Malfunctioning coolant pump (eroded or broken impeller blades) | Replace the coolant pump. Refer to Water Pump Replacement . |
Air trapped in cooling system | Refill the cooling system. Refer to Cooling System Draining and Filling |
- Verify that the cooling system is properly filled.
- If the complaint is a low temperature gauge reading, check the temperature gage for proper operation. Connect a scan tool to the vehicle and read the system temperature.
- Compare this reading to the temperature gauge.
- Replace the gauge or switch if necessary.
- If the complaint is no heat from the HVAC system, refer to Heating Insufficient in Heating, Ventilation and Air Conditioning.
- Verify the proper operation of the thermostat.
Engine Overheating low Coolant Lamp On
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
DEFINITION: The engine temperature lamp comes on and stays on, or temperature gauge shows hot, or coolant overflows from the surge tank onto the ground while the engine is running. | ||||||||
1 | Check for a loss of coolant. Refer to Loss of Coolant . Is there a loss of coolant? | -- | ||||||
2 | Fill the system to the specified level. Refer to Cooling System Draining and Filling . Does the engine still overheat? | -- | System OK | |||||
3 | Check for kinked or pinched surge tank hoses, especially at the radiator. Are any surge tank hoses kinked or pinched? | -- | ||||||
4 |
Does the engine still overheat? | -- | System OK | |||||
5 | Check for loose, missing or damaged radiator air seals or deflectors. Are there any loose, missing or damaged radiator air seals or deflectors? | -- | ||||||
6 | Repair or replace any loose, missing or damaged radiator air seals or deflectors. Refer to Radiator Air Baffle Assemblies and Deflectors . the engine still overheat? | -- | System OK | |||||
7 | Check the coolant concentration. Does the coolant concentration test correctly? | -- | ||||||
8 | Replace the coolant if necessary. Refer to Cooling System Draining and Filling . Does the engine still overheat? | -- | System OK | |||||
9 |
Important: Use the correct pressure cap. Check the system for loss of pressure. Refer to Cooling System Leak Testing . Is there a loss of pressure? | -- | ||||||
10 | Repair any leaks as necessary. Does the engine still overheat? | -- | System OK | |||||
11 | Check for a faulty engine coolant temperature sensor (ECT). Is the engine coolant temperature sensor faulty? | -- | ||||||
12 | Replace the ECT. Refer to Engine Coolant Temperature Sensor Replacement in Engine Controls - 2.2L or Engine Coolant Temperature Sensor Replacement in Engine Controls - 2.4L. Does the engine still overheat? | -- | System OK | |||||
13 | Check the radiator for any air flow obstructions or bent fins. Is there any airflow obstruction or bent fins? | -- | ||||||
14 |
Does the engine still overheat? | -- | System OK | |||||
15 | Check for any blocked cooling system passages. Are there any blocked cooling system passages? | -- | ||||||
16 |
Does the engine still overheat? | -- | System OK | |||||
17 | Check for an inoperative cooling fan. Is the cooling fan inoperative? | -- | ||||||
18 | Replace the cooling fan. Refer to Engine Cooling Fan Replacement . Does the engine still overheat? | -- | System OK | |||||
19 | Check for a thermostat that is stuck closed. Is the thermostat stuck closed? | -- | ||||||
20 | Replace the thermostat.
Does the engine still overheat? | -- | System OK | |||||
21 | Check for a faulty water pump. The impeller blades may be eroded or broken. Is the water pump faulty? | -- | -- | |||||
22 | Replace the water pump.
Does the engine still overheat? | -- | -- | System OK | ||||
