I just wondered if anyone else has experienced this or may know what it may indicate. I have a 1987 Celica ST (plain jane). The coolant temperature gauge has (on occasion) went straight to the red zone (I mean in 1 second) when started cold. If I turn it off and back on it straightens out. This has only happened about 3 times before today. But today, about 1 mile out of the driveway, the gauge went from barely-warm (had just started to climb) straight to red, then back to barely-warm, then did it a second time. I have driven over 150 miles since that without any repeats. The coolant level is (and has been) fine/perfect and even if the water pump somehow stopped working (impossibly/silently) momentarily, it happens when it is not even at operating temperature. There is no wiring that looks visibly damaged. Any insight? Something (sensor?) fixing to go out maybe? Thanks for any insight/experiences. Tracy
Thermostat? Coolant temp sensor? I had the same issues. Replacing both fixed them. Of course this is after I blew my head gasket.
Classic sign of the coolant temp switch either with a poor connection, or more likely the sensor itself breaking down. Mine did the same, swapped it out for a new one. All fine again
Definately NOT the termostat. How could it go in the red zone at cold start?? More like sensor / wiring issue as Alwayzsidewayz said.
Thanks all. I knew it couldn't be the thermostat because as someone already stated, none of the coolant was even hot yet (plus I had changed the thermostat out a few months ago when I found it to be "sticking" ... and tested the new one in boiling water). I will look for a new coolant temp sensor. One more question - Is the sensor that I am looking for the one that goes into the thermostat housing or is there one that goes someone where else like into the radiator? I ask because after looking at the connection (on my car) for the one at the thermostat housing, I see different connections for all of the ones on RockAuto, AutoZone, etc. Thanks!
http://www.st162.net/forums/viewtopic.php?f=32&t=4122&p=50993#p50993 Why is it every week somebody creates a new thread on this?
Sorry Stig, I neglected to search I think :crazy So what is the sensor on the thermostat housing then?
^That's the radiator fan switch sensor. It's reverse-wired, so if it fails, the fan will always stay ON. To test it, turn the key in your ignition to 'ON' (but don't start car). *Keep yourself clear of the radiator fan* Then unplug the sensor. The fan should come on.
