Temperature Gauge Issues

pearl95sc

Registered User
Alright, this problem is out in left field, I can't figure it out. Finally filled coolant system. Figure now, I can let the car run ong enough to get it at operating tempature, make sure all is well. Before, when I did an initial start, just to check everything and make sure all was well, I fired the car up with no coolant, ran it maybe 20 seconds at best. The temp gauge went from freezing to hotter than hell the minute the car fired up. Now, coolant is in the system, the gauge still does the same thing. The odd part is, when the ignition is on, car not running, gauge sits at freezing, fire car up, gauge goes to ridiculuously hot area immediatly. I checked both the connectors at the stat housing, and nest to the pass. side valve cover. Both are clean and on snug. Any thoughts on this one anybody. It's really getting on my nerves and I don't want to run the car too long without knowing the actual temperature. I know the check gauges light will flash and the chime will ding if coolant is in the danger zone (fan fuses blew on a 85 degree day), so I can rule that out. I need help fast, I'm off all day tomorrow, and I want to let it run a little, make sure all is well.
 
I think you have air in the coolant system. You need to burp it. There is a white circular top that you have to remove when filling the coolant...did you remove that when you did? Follow the procedures in a manual and it should take care of the air in the system. That is what it sounds like to me, but I have not accomplished this yet on my car. I usually let someone else do it every two years (flush and fill).
 
If without coolant the gauge goes to hot immediately on start, you have an electrical problem. The temp sending unit is a thermistor that the resistance goes down as temp goes up so a short shows up as hot.

Engine vibration could be causing the wire to short out. You would not see the gauge move because it is designed to respond very slow.

You can check the temp sensor with a hair dryer and a volt meter. The temp gauge can be checked with a 100K potentiometer.

Code:
 ground----/\/\/\/\-----sensor wire
             ^____|

	    Wiper shorted to either leg
Aaron
 
I agree with Aaron, the car couldn't heat up that fast...most likely something is wrong with the sender or it's wiring.

David
 
All the wiring is good. I checked all before putting it back on, made sure all was taped up and loomed right. I agree in thinkin there still may be air in the system. How do you "burp" the air out. All the hoses feel nice and hot, like there's coolant in them, but they do feel like there may be some air in them too. This is new to me on how to bleed the air out with this car. Any help's appreciated. Thanks, Alyn
 
There's a bolt on the thermostat housing that should have a yellow plastic ring around it, loosen the bolt until the holes in the sides of the threads show and let it run until all air is out.
 
the eastiest thing you could do is go and check and physically feel your car, rad hose etc and then you would know if its hot :)

That would rule out the car heating up to hot in 1min which I think is impossible but who knows lol
 
Thanks for the bleeding instructions Mattix. I'm gunna give it a try and see what happens. I got gauges on the way, so soon enough, i'll know for shure.
 
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