Core Sand Contamination (3.2L Engine)

Excess foundry core sand can cause an intermittent loss of heater duct outlet and engine temperature due to sand holding the thermostat open. Initial engine warm up is generally not effected. This problem most commonly occurs during sustained cruise at highway speeds in cool ambient temperatures (or after partial warm up drives).

1. Shine a flashlight into the plastic coolant hot bottle next to the filler cap. View the bottom side of the bottle with an adjustable mirror. Sand, if present, will appear as a dark shadow. All vehicles may show some evidence of core sand accumulating in the front, passenger side section of the hot bottle. An acceptable amount of sand will look like a spot approximately the size of a quarter. Anything more is an excessive amount.

2. If sand is not excessive, remove thermostat as described on page 7-19 of the service manual. Inspect thermostat to see if it is propped/stuck open. If propped/stuck open, call STAR Hotline during the vehicle launch period for a replacement part. Replace thermostat and re-run 3.2L Engine Diagnosis steps 3-4. If not propped/stuck open, proceed with the next step.

3. If core sand appears to be excessive, the following procedure can be used to determine if it is causing a heater performance problem.

NOTE:
THIS PROCEDURE IS EASIER TO PERFORM IN LOW AMBIENT TEMPERATURES BECAUSE THE ENGINE TEMPERATURE FLUCTUATIONS WILL BE MORE SIGNIFICANT AND THEREFORE EASIER TO SEE.

4. At 65 mph put vehicle in low gear or 2nd gear if Autostick. Drive for about 1/2 mile between 4500 and 5500 engine rpm.

5. Engine temperature should drop due to flow of cold coolant forcing thermostat open.

6. Put vehicle back in overdrive and maintain 65 mph for a minimum of three miles. Coolant temperature should return to 180 °F minimum.

7. If coolant temperature does not return to 180 °F, but continues to drop, the thermostat has been held open by core sand. If this is the case, please call the STAR Hotline during the vehicle launch period for repair instructions.

8. If the coolant temperature returns to 180 °F min, repeat steps 4-7. Repeat steps 4-7 three times, if after three tries the coolant temp gauge always returns to normal, core sand is not the problem.

9. If problem persists, call STAR Hotline during the vehicle launch period for further instructions.