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Ken
Ken, Saturn Mechanic
Category: Saturn
Satisfied Customers: 754
Experience:  GM & SATURN FACTORY TRAINED
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1997 saturn: that is overheating..thermo..water pump..running hot

Customer Question

I own a 1997 Saturn Sl2 that is overheating. I had my mechanic check the car and he found that the thermo was broken into pieces and he changed the thermostat and the water pump. my car is still running hot. The overheating light is flashing continuously. I do not have problems with high oil usage and have only had to fill the radiator since it started running hot. Any ideas?.
Submitted: 7 years ago.
Category: Saturn
Expert:  Ken replied 7 years ago.
Hi and thanks for your question! Is trermo = the thremostat? Ken
Customer: replied 7 years ago.
yes, i'm sorry. I meant thermostat.
Expert:  Ken replied 7 years ago.
I want you to have a look at the coolant temp sensor. I see a lot of them that crack and then lie to the computer. It can leak coolant into the connector. Read over the information I am sending you and let me know if you need more help. You may also have a coolant cap tat is not holding the right pressure. They should hold 15 psi bu when they start going out they may only hold 8psi. Let me know what you think and find after you read and have a look at the temp sensor. Thank You Ken

Subject:Engine Coolant Temperature Sensor Related Diagnostic Trouble Code(s) and/or the Following Conditions: Hard Start, Erratic Idle, Rough Running, Engine Overheating, LOW and/or Leaking Coolant, and/or Service Engine Soon Lamp Illuminated. (Replace Engine Coolant Temperature Sensor with new Design Sensor - P/N 21025106)

Models:1991 - 2001 Saturn S-Series vehicles

 



Condition

Customers may comment about various driveability and/or engine operating concerns including: hard start, erratic idle, rough running, engine overheating, low and/or leaking coolant, and/or Service Engine Soon lamp illuminated.

Cause

This condition may be caused by a cracked engine coolant temperature sensor.

Correction

Replace engine coolant temperature sensor, inspect and if necessary replace sensor harness connector. Refer to procedure in this bulletin to replace engine coolant temperature sensor and Parts Requirements for specific parts information.

PROCEDURE


Object Number: 870336  Size: SH

  1. Disconnect engine coolant temperature sensor electrical connector and inspect sensor connector terminals for corrosion and/or evidence of engine coolant
    If terminals are corroded or if there is evidence of engine coolant, proceed to step 4.
    If terminals are not corroded and there is no evidence of engine coolant, reconnect the electrical connector and continue to next step.

    Caution: TO AVOID THE DANGER OF BEING BURNED, DO NOT REMOVE THE CAP WHILE THE ENGINE, RADIATOR, AND SURGE TANK ARE STILL HOT. SCALDING FLUID AND STEAM CAN BE BLOWN OUT UNDER PRESSURE.

     

  2. Perform one or both of the following checks to determine whether the engine coolant temperature sensor is providing the correct temperature indication.
    If engine is at ambient temperature (vehicle has been sitting overnight or not started for several hours), use a Scan tool to compare the inlet air temperature (IAT) to the engine coolant temperature (ECT). These two readings should be within 2° C (4°F) of each other.
    If engine is at operating temperature, install a thermometer in the coolant recovery reservoir. With the engine running and A/C off, use a Scan tool to compare the engine coolant temperature sensor reading to the thermometer reading. These two readings should be within 8° C (15° F) of each other.
    If engine coolant temperature sensor reading does not pass either of the above tests, continue with next step.
    If engine coolant temperature sensor reading passes both of the tests above, refer to appropriate symptom diagnostic chart in the Engine/Emissions Control Section of applicable Engine Service Manual.
  3. Turn ignition Off.
  4. Remove coolant surge tank cap.
    Object Number: 881701  Size: SH

    Caution: DO NOT REMOVE CAP OR OPEN COOLING SYSTEM DRAINS FROM A HOT SYSTEM. ALLOW SYSTEM TO COOL FIRST.

  5. Drain at least 1.9L (2 Qt.) of engine coolant from the cooling system by opening radiator drain valve or removing engine drain plug. Collect
  6. Disconnect engine coolant temperature sensor electrical connector.
  7. Remove engine coolant temperature sensor from cylinder head.
  8. Obtain replacement engine coolant temperature sensor (P/N 21025106).
  9. Use appropriate tap to clean sensor mounting hole of any thread sealant residue.
  10. Install engine coolant temperature sensor in cylinder head.

    Tighten
    Engine Coolant Temperature Sensor: 8N·m (71 in lbs)

  11. Inspect harness connector terminals for corrosion and/or evidence of engine coolant. If harness connector terminals are corroded or there is evidence of engine coolant. The harness connector must be replaced with new connector (P/N 12117087- includes : connector, terminals, wires, and splice sleeves).
  12. Connect engine coolant temperature sensor connector.
  13. Transfer engine coolant drained in step 5 into coolant surge tank. If necessary fill coolant surge tank to the FULL COLD range with 50/50 solution of correct type of antifreeze and clean water.
  14. Start engine and check for leaks.
  15. Run engine until upper radiator hose is hot, then add additional coolant if needed, to bring the level to the FULL COLD level (1991 -early 1997) or within the Min./Max. cold range (late 1997-2001).
  16. Install coolant surge tank cap.

PARTS REQUIREMENTS

21025106

Sensor-Coolant Temperature

12117087

Connector-Engine Coolant Temperature Sensor

Ken and 3 other Saturn Specialists are ready to help you
Expert:  Ken replied 7 years ago.
Does the radiator fan motor turn on? I see the motors go out also. If you turn on the A/C the fan motor should turn on. You need to make sure the A/C compressor turns on and then see if the radiator fan turns on. Ken