coolant temp gauge screwy as heck

[sixleggedinsect]

long story short:

for a few months now, my coolant temp gauge has been acting seriously screwy. generally, it reads nothing at all (needle all the way left, beyond the cold mark). however, it jumps up to the correct temperature occasionally, always while coasting down a hill or while decreasing the throttle a lot. the needle immediately drops back past 'cold' when the accelerator is re-applied.

i replaced the sensor a few days ago. for the test drive it seemed to work. the needle slowly crept up to temperature over the course of five or ten minutes of driving. then i parked the car, and it has been acting screwy again ever since. same symptoms as before.

the only difference is the operating temperature displayed during those coasting periods seems to have changed. the gauge reads a lot colder than it used to. i removed the air intake silencer, changed the thermostat, air filter, and obviously the sensor. could any of these be responsible for the changed coolant temp? could the thermostat be faulty?

thoughts?

anthony

[Jet-Lee]

I noticed on my '99 LX, that after putting in a new thermostat, even though it's the same 192 degree, my engine runs a lot cooler. As to your problem, a short somewhere, that is blowing your temp sensor when you shut the car off?

[willye]

Hey ant,

I have fought the coolant temp problem for a long time. My suggestions to you: Get a good quality temp gauge and put it in where the oem gauge sensor goes in the heater hose. See what your actual temp is running.

The magic bullet for my escort was taking the car to a radiator shop and tell them to flush the hell out of it, especially the heater core. AFter that, much better now. Believe me, I did everything possible prior to the flush, including the do it yourself flush (did not work) . DO THE PROFESSIONAL FLUSH! Be sure to tell them your problem and ask them to tell you if their service will likely fix it.

[sixleggedinsect]

Originally Posted by Jet-Lee

I noticed on my '99 LX, that after putting in a new thermostat, even though it's the same 192 degree, my engine runs a lot cooler.

hm. i dont know enough to be able to say its not a problem. what would be the symptoms of a faulty thermostat?

As to your problem, a short somewhere, that is blowing your temp sensor when you shut the car off?

(sigh), guess i have to break out the multimeter and the probes. i was hoping someone would say 'dude! that happened on my car! all you need to do is reconnect the **** again!'

no such luck

[sixleggedinsect]

Originally Posted by willye

Hey ant,

I have fought the coolant temp problem for a long time.

thanks for the suggestions. out of curiosity- were your coolant temp problems similar to mine (i feel like mine are particularly specific and consistent) or did you have a different set of symptoms (not that both sets of symptoms coudlnt be caused by the same problem..)

thanks!

[mustang302]

Check the connection to the temperature sending unit. A bad connection could result in your described symptoms. The plug could be so cheesy you might need to replace it.

[willye]

[quote=sixleggedinsect]thanks for the suggestions. out of curiosity- w


My temp was consistently cool. You may be dealing with a bad wire connector to the sensor.

If not sure -- get a real gauge!

[sixleggedinsect]

[quote=willye]

Originally Posted by sixleggedinsect

thanks for the suggestions. out of curiosity- w


My temp was consistently cool. You may be dealing with a bad wire connector to the sensor.

If not sure -- get a real gauge!

hmm. that actually makes a lot of sense. the sensor only reads when decelerating, it seems. maybe there is a short or bad connection such that the sensor only 'connects' when there is a decelerating force. ill need to get someone to wiggle the wire while the car is running at temperature. if the gauge reads the actual temp, im in business.

the only time ive played with the wire was when i reinstalled the new sensor. that wiggling might have jiggled things into place such that it worked like normal for a few minutes, then settled back into its groove.

anyways. enough hypotheses. time to play with wires.

thanks,
anthony