I have the following issue with my 2007 Caravan. Just had the rad replaced cause it was leaking. Symptoms, while idling temp goes up to normal range. While driving, winter in Canada, temp gauge drops back to almost cold, I can feel temperature inside dropping off. I have replaced the Thermostat twice in the last week and still the same above conditions, idling temp goes up but drops back to well below normal after driving for a while. Any suggestions?

 

How cold is it outside?

Welcome to DF!

 

Yesterday the outside temperature hovered around the 0 degree Centigrade mark, not real cold for this time of the year.

 

What brand/type of stat are you installing? Not one of the 'safety stats' by any chance is it? Sure seems like a thermostat issue..... If you haven't already, try installing a stant superstat. that *should* solve the issue.

 

You hijacked another guys thread and I posted there. Now I see this one and copied and pasted my suggestions to you here. hehe. Keep checking your coolant level after changing your radiator. Air pockets can make funny things happen. Park facing up on a big uphill or on car ramps so that your radiator is much higher than your engine. This will chase the air easier to the cap. Hold it at 2500 rpm for a couple of minutes and then shut it off and let it cool before checking. If your radiator is full, and you cool down abnormally while driving, your thermostat is sticking open, no question about it. If your radiator is full and your thermostat was acting normally, you would have heat and a normal engine temperature at idle and on the road. Your thermostat is wrong, maybe backwards or upside down if that is possible I don't know. You heat up when idling because no airflow through the radiator. You take it on the road and it cools down because you have airflow through the radiator when driving. This tells me your coolant is running through your radiator all the time. If your coolant is always running through your radiator, you will never heat up enough. It is the thermostat's job to close and open only when engine temperature is high and allow some coolant to go through the radiator. Did you do the thermostat? Did you get a good one? Make sure it is the oem temperature, sometimes they make 185 and 195 degree ones. Sometimes crap brands make junky ones. Autozone or whatever will tell you which is oem temperature. Good luck.

 

Thanks mirageman and all, very good tips. Well I tried 2 Thermostats from Canadian Tire with no success so I went to the local Napa Auto and got one from them. I installed and filled coolant using the trick of parking on a hill. Rev the engine to 2500rpm for a couple on minutes. Temp gauge when up to shy of half, normal good running range. Then I took it for a good drive, low and behold temp gauge stayed at the good running range. So the bottom line was whether or not it was the thermostat or air bubble that was the cause of the issue. It's working now so I'm not going to play with anymore.

Cheers and Merry Christmas and a Happy new year to one and all.

 

Merry Christmas and a Happy New Year to you as well! Glad for ya!