I have an 05 grand prix with the 3.8 liter naturally aspirated engine and have been having trouble with intermittent heat.The heat can be fine for a day or two and then the coolant temp will drop as will the heat coming from the heater. I have put in a new thermostat, bleed the system and topped up the coolant but still the same. The engine oil is its normal color. I removed the rad cap with the engine running but did not see any bubbles in the coolant.I removed three spark plugs from the front of the engine and they were a little white.Any help would be appreciated.
Originally Posted by W-Body Store
