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PT Cruiser Overheating

Hello All! I have been having an overheating issue with my 2002 PT Cruiser for the past several months. I have tried numerous repairs and so far no luck. THe car has 76K miles. Here is a list of what has been done so far:

1. Replace Thermostat

2. Replaced Radiator cap

3. Replaced ECT Sensor

4. Checked for exhaust gasses in coolant (negative)

5. Replaced High and Low speed Relays

6. Checked radiator fan motor by jumping directly to battery, both high and low speed work.

7. Checked radiator temp with IR thermometer, temp variance not greater than 15 degrees over entire surface area.

8. Replaced engine coolant.

9. Checked for vapor lock in system (negative)

I am at a loss as what could be the problem. The car tends to overheat more at slower speeds and with the air on than at higher speeds. In all cases turning the heat on high pulls enough temp from the engine to keep it under control.

Any help would be greatly appreciated.


The overheating might be caused from erroded water pump impeller blades. At slow speeds the erroded blades can’t pump the coolant thru the radiator fast enough to prevent the engine from overheating. At higher speeds the erroded blades spin faster thereby pumping enough coolant to prevent the engine from overheating.


Even though the radiator’s temperature doesn’t vary much, that does not mean it’s dissipating heat sufficiently. An evenly coated inside will still be a bad radiator.

You’ve not checked the flow from the pump. The impellars can become eroded and the pump not move fluid sufficiently.

Radiator hoses can collapse internally and restrict flow if the lining seperates fron the fiber-impregnated outside.

If all these check out okay, I’d want to do a pressure leakdown test on the cylinders even though you found no evidence of exhaust gasses in the coolant. Just to be sure.

Here is something to try that won’t cost you anything: Take a garden hose with a nozzle and direct the stream from the engine side of the radiator out through the grille. You might be amazed at the debris and dead bugs you can flush through the honeycomb of the radiator. An air hose would also work.