Thermostat question

[Huskymaniac]

Originally Posted by SoCal LS-L

I thought our gauge was controlled simply by a thermistor? Mine also fluctuates between norm op and slightly cooler than that due to the thermostat delay in closing. I know my engine cools below norm op within about 30 seconds of reaching the peak of mt rose pass and descending, especially if the heater is on. If the engine runs hot it sure takes more than a windy mountain climb to do it.

That is true but the gauge itself has a zener diode in it that causes the gauge to be nonlinear so that the needle will not move while the temperature is within a certain range. The temperature is still varying and so is the thermistor resistance but the gauge is not responding.

[SoCal LS-L]

Originally Posted by Huskymaniac

That is true but the gauge itself has a zener diode in it that causes the gauge to be nonlinear so that the needle will not move while the temperature is within a certain range. The temperature is still varying and so is the thermistor resistance but the gauge is not responding.

[Awox]

Not 100% on the functionality of my dead zone then. Mine frequently goes back and forth between half a just under half of the gauge as driving conditions vary. The fans kick on when it reaches the halfway mark, then it drops to just under half, about the width of the needle and they kick off. It will drop maybe another half needle width before leveling off or rising again depending on driving conditions. If there's plenty of airflow it will stay 1 needle width below midpoint, in stop and go with AC on it will keep rising to midpoint and kicking the fans on every few minutes. On some serious hills the fans kick on but I've only gotten it to do that once from heavy pedal usage. If the fans kick on at the same time the car starts to pick up speed and airflow acrossed the radiator, sometimes the temp drops pretty far, but picks right back up to normal once the fans stop.

I never see it sit still... Could this be a thermostat problem? It seems perfectly normal to me though, it corresponds 100% correctly to what's going on, driving conditions wise.

[Huskymaniac]

Originally Posted by Awox

Not 100% on the functionality of my dead zone then. Mine frequently goes back and forth between half a just under half of the gauge as driving conditions vary. The fans kick on when it reaches the halfway mark, then it drops to just under half, about the width of the needle and they kick off. It will drop maybe another half needle width before leveling off or rising again depending on driving conditions. If there's plenty of airflow it will stay 1 needle width below midpoint, in stop and go with AC on it will keep rising to midpoint and kicking the fans on every few minutes. On some serious hills the fans kick on but I've only gotten it to do that once from heavy pedal usage. If the fans kick on at the same time the car starts to pick up speed and airflow acrossed the radiator, sometimes the temp drops pretty far, but picks right back up to normal once the fans stop.

I never see it sit still... Could this be a thermostat problem? It seems perfectly normal to me though, it corresponds 100% correctly to what's going on, driving conditions wise.

It could be a stuck open tstat but it also could be the temperature sender for the gauge. Mine went bad and caused the temp to read low which caused the needle to drop out of the dead zone.

[Awox]

You might be right about it sticking open. I originally thought that was the case, but convinced myself that what it was doing is normal. I'll check into it.

[Huskymaniac]

Originally Posted by Awox

You might be right about it sticking open. I originally thought that was the case, but convinced myself that what it was doing is normal. I'll check into it.

You might want to replace the temperature sender for the gauge first. It is cheaper and easier. Make sure you get an exact replacement from Subaru though.