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No temp gauge, cold radiator!

crysalis

crysalis

New member
Hey all,

I'm thinking/hoping this is a quick one. Last week, I was driving on the highway and I looked down and noticed my temp gauge was as low as it goes. No SES light. The heater was working fine, so as precaution, I set the heat as high as it would go. I came to a stop and the fans were on high. No leaks, and barf bag full of coolant. So, I thought the temp sensor kicked the bucket. Took old one out and coolant flowed out as expected. I just finished (painfully) replacing it an hour ago. Unplugged the battery for 15 minutes and started her up. I let it warm up so that I felt heat from the vents. Still no temp reading and fans still on high. This time, I felt around the radiator and hoses... both upper and lower hoses are cold and the radiator's coolant was ice cold.

Thermostat? I just flushed the system last year when I did the heater core. I just wanna get opinions before I throw parts at it. Instinct tells me the thermostat is stuck.
 


these temps sensor are bad brand new right out of the box a lot it seems.

check the wires to the sensor. its got a short pig tail that runs to the upper manifold area under the dog bone. if the wires look ok, exchange the temp sensor.
 
Seems to me that the radiator would be hot... or at least warm... if it was just the sensor, no? With the limited tools I have, it was a PIA to change so I'm hesitant to change it again (I broke the first new one, so I've essentially had 3 sensors today).

I had the car running for 30 minutes and heat was a plenty. I shut it off and the radiator was ice cold (I stuck my finger in the coolant) and both hoses cold.
 
if the fans are on all the time, that means the sensor is not working, either its unplugged, bad wires, or its shot out of the box.

as far as heat, sure you'll have heat. and the rad hoses will be ice cold as well as the rad due to the fans being on. and the t stat staying shut most of the time.
 


Wiring seems OK, but hard to tell since it is wrapped in the black plastic shielding.

I'm gonna try to test the sensor with my multimeter later and see if I get anything.
 
unplug the sensor, then pull the wire out and unplug it from the main harness. then un wrap it. look for cracks or bare wire showing.
 
crysalis said:
I had the car running for 30 minutes....and the radiator was ice cold (I stuck my finger in the coolant) and both hoses cold.
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What?? No it should never be ice cold after 30 minutes. The upper hose should always be at least warm even when below 0°. The thermostat isn't opening or something (not related to temp gauge malfunction)
 
02NavyBlue said:
What?? No it should never be ice cold after 30 minutes. The upper hose should always be at least warm even when below 0°. The thermostat isn't opening or something (not related to temp gauge malfunction)
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not if the fans are stuck on. rad will be ice cold. the t stat will only burp aka open for a short amount of time, once cold coolant hits the t stat it shuts again. this will happen over and over. rad will never get hot. especially if its cold out side.
 


not really. mine was ice cold today after a high way drive and sitting idling for a good 20 minutes. rad cap was ice cold too. and my fans are not stuck on. just 30 deg's out. heat was hot, temp was normal.
 
I'll check again on the way home tomorrow, my upper hose has been hot after every drive I've taken, that I've felt it. The lower is always cold I bet (in this weather). The upper hose is straight out of the engine, should be around 195° unless absolutely nothing is flowing.
 


Haven't had time to check sensor or wiring yet. Visually, it looks ok. Car is sitting in garage for now anyway.

Scotty is correct... both hoses are cold... tstat is not opening. Only the very bottom of the upper hose is even remotely warm... i imagine because very little (if any) water is flowing. It's just staying in closed circuit. That's why I originally thought it was the tstat, but obviously its something more with the sensor since temp gauge refuses to budge and fans immediately go on high.

If nothing else, a friend of mine has access to a Tech II for the time being so I'll let him have a look if the wiring tests fine. My bet is it is the pigtail that is near the exhaust crossover... the wires are within an inch of the crossover.
 
if the engines not over heating, the t stat is just fine. the fans staying on is what keeping everything cold.

those wire can get crispy for sure. but those sensors also are known to bad brand new, right out the box. its happened to more then a few guys.
 
I have a similar problem with my 02 gtp. I swapped the stock tstat to a 180 degrees and now the temp gauge sits just under the 1/4 line, maybe a tick under or 2. Seems to warm up if I drive it in traffic then once on highway will drop again... Hasn't hurt anything. Would love to fix this issue tho let me know if u find a fix.
 
Dustoff said:
I have a similar problem with my 02 gtp. I swapped the stock tstat to a 180 degrees and now the temp gauge sits just under the 1/4 line, maybe a tick under or 2. Seems to warm up if I drive it in traffic then once on highway will drop again... Hasn't hurt anything. Would love to fix this issue tho let me know if u find a fix.
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put the stock 195 back in, your mpg are suffering. so it is hurting it somewhat. your engine wa made to run at 210 deg's. thats where it runs its most efficient.
 
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