GHOST05

Hi all,
I am new to the forum, and have had an issue that I thought all of you may be able to help me with. First off, I did a search on the forum (so I don't repeat anything that anyone has already talked about) and the step-by-step post on the overheating check is awesome. That was easy to follow and was really detailed, and I wanted to say thanks to all of you who chimed in. Here is the question that I had on it. After doing a combustion check, changing the radiator cap and thermostat, having the water pump changed when I got the timing belt changed last year, and doing a complete back flush (just in case the heater core or radiator may have been clogged), my car still jumps up in temperature. Of course, it's ok when I drive to work (an hour drive), and acts up when I get in a traffic jam. The thing that is puzzling me, is that when the temperature dial on the HVAC system in the car is turned to cold, the car is fine. It will not jump in temp at all, but when I turn it to a hotter setting, it starts to jump up. If I notice it jumping up, and turn it back to cold, it drops back to normal like clock work. This happens with the blower off or on. It seems like it acts up on the third day. The reservoir is not filled up to the top with coolant, and it looks as if the radiator is full. I also bled the sytem like the post stated (with the car jacked up, etc), and the fans come on when the blower is on, and when the temp jumps up. Could this still be a head gasket, or should I try to change the radiator? That and the Heater core are the only two components I have left to change besides jumping into the head gasket. Has anyone encountered anything like this?

Thanks in advance!

anibis

Have you swapped out the Coolant Temperature Sensor?

Did you have the same problem before you changed the thermostat?

GHOST05

Yes, I had this problem before I swapped out the thermostat. What I did this past weekend was throw in a new radiator and temp sensor anyhow because I was still not completely sure about the radiator. After I pulled it out, I found that the bottom corner (under the filler neck) looked pretty beat up. Having done that, I think that it is the HG, even though the signs are not obvious. So, I ordered some new parts and will tear into it hopefully by next week. Thanks again for your help.