Engine temp drops at stop lights?

[fireguy12117]

I've been noticing on the colder days in michigan that when i hit a stop light, the temp gauge starts to drop and the air coming out of the vents gets cooler.

I assume the coolant thermostat is opening and closing when i idle.

Is this just because the smaller 4 cylinder just doesnt produce enough heat to overcome the really cold days? or is something else going on here?

everything else seems fine with the truck, and when i get a little gas while stopped, the temp starts to come back up.

 

[TimR]

possibly low coolant, (air pocket), or loose drive belt?

 

[modelageek]

possibly low coolant, (air pocket), or loose drive belt?

+1 I had this issue with my truck as well. the coolant was low and the sensor was not submerged. when you revved the engine coolant would flush over the sensor............fill your coolant and get the air out...........but remember these trucks run cold so the heat is not always great at idle anyways..

 

[fireguy12117]

cool, thanks guys, i'll check the belt and coolant level.

it still confuses me though, i thought these engines had mechanical thermostats which means the actual temp would have to dip low enough to cause the thermostat to shut, thereby causing the cold air flow out of the heater core...i guess i dont see how a low level would cause such a drastic temp swing from cruising to idle/stop unless the radiator can really transfer off all that heat that quick...

 

[TimR]

cool, thanks guys, i'll check the belt and coolant level.

it still confuses me though, i thought these engines had mechanical thermostats which means the actual temp would have to dip low enough to cause the thermostat to shut, thereby causing the cold air flow out of the heater core...i guess i dont see how a low level would cause such a drastic temp swing from cruising to idle/stop unless the radiator can really transfer off all that heat that quick...

it has nothing at all to do with the thermostat, it is the air pocket stopping the flow to the heater core, and giving a false reading to the temp sensor... follow?

 

[fireguy12117]

nearly a gallon low on the coolant. im kinda freaked that its that low! i guess i will be looking for signs of coolant losses either external or internal since that seems excessive. i cant remember the last time i ever check it since i barely ever have to do anything to this truck.

 

[flaminranger]

turn it into a beater so you have to work on it all the time that way you check everything all the time.lol or just make a note and stick to it

 

[fireguy12117]

my wife drives the 93 in the sig- that truck gives me plenty to work on, lol. seriously though both trucks have been great really.

thanks for everyone's replies. The truck stays warm now and i think i even gained a little mpg's back.