Engine Temp Drops to COLD when driving!? [Archive] - The Chrysler Minivan Fan Club Forums

: Engine Temp Drops to COLD when driving!?

02-09-2005, 12:33 PM
What would cause my temperature gauge to drop to Cold while driving? When I stop and let the engine idle, it returns to the normal range.

02-09-2005, 12:49 PM
Could be that your thermostat is stuck in the open position which doesn't allow the coolant to heat up when you drive.

02-09-2005, 05:50 PM
Is your coolant actually getting cold, or is it just your temperature reading? If your heater still blows out hot air, I'd check the temperature sending unit and/or its connections. Otherwise, the thermostat is probably failing.

02-09-2005, 07:01 PM
What engine. I've seen this happen with a bad head gasket.

02-09-2005, 09:14 PM
my vote is for stuck open t-stat.. exactly the symptoms of that..

02-09-2005, 09:30 PM
Will definately replace the Thermostat & see if that works first.

Not sure about the actual temp of the coolant. Have not checked it.

I have had a BHG on a Supra in the past and temp actually fluctuated. That was also accompanied by the water rushing & gurgling sound near the firewall.

She has 167,000 miles... Im not going to rule out the BHG on the caravan, but symptoms have yet to convince me.

Thanks folks for all your help!

02-09-2005, 11:25 PM
are the radiator fans running?
if they are, check the fan relay

03-13-2005, 03:03 PM
had this happen on my 97 3.0 voyager. checked the thermostat and it came out in two pieces. replaced it and temp. went back to running normal.

03-18-2005, 03:43 PM
If your thermostat failed, it wouldn't turn cold while driving. It would never get hot. THe thermostat is supposed to open as the water temp goes up. If it is stuck open, the water would never heat up. When your indicator is cold, are you getting heat from your vents?? If you are getting heat instead of cold air then your thermostat is working OK.

If you are getting heat from your vents, the indicator is reading cold, that means you have trapped air in your system (HG failure) or the sensor has failed or the wiring is faulty.

If you have a cracked HG, you should be able to see bubbles in your coolant either by opening the rad cap or monitoring the expansion tank. I hope you know this, but don't open hot radiators. Open the rad cap when cold and crank the engine on. If you have a cracked HG and you are getting exhaust gasses into the cooling system, you will see bubbles. If your HG is leaking on the intake side and not the exhaust side, it will actually draw coolant into the combustion chamber and burn it. It will billow white smoke from the tailpipe.

There are slight variations from this, but this information holds true for most circumstances.

From what you described, I would look first at the connnectons on the temp sender, then check for HG leaks, then replace the sender.


04-24-2008, 09:59 AM
I disagree. I have a 1997, 3.0 L. It would warm up nicely, and drive along with heat, but when going down grade (coasting) temp would drop to cold. Put in new thermostat, been perfect ever since. Funny things aren't they? Thermostats I mean!

04-25-2008, 03:47 AM
Gotta say it - there's exceptions to every rule.