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Tempurature Sensor


Nick68's Avatar
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03-19-03, 05:24 PM   #1  
Nick68
Tempurature Sensor

Hello,
I have a ’92 Ford Ranger pick up with a 3.0V6 and 5 speed manual transmission. It has about 207,000 miles on it. I put a new (used) engine in at about 180,000 miles and a re conditioned trans about 3 weeks ago. When I bought the engine it had about 30,000 miles on it. It came out of a wreaked Windstar. I think it might be coincidental but after I put the transmission in the temperature gauge started to act erratic. It moves just into the normal range (but towards the cold side, not where it used to ride) and then abruptly drops all the way to the left. (like the engine was off) Then it slowly creeps back up and does it again. The engine seems to be running at normal temp. I can feel the coolant in the upper hose and the engine feels like normal. My first thought is the temperature sending unit is bad but I don’t know how to test it. All the connections seem to me tight and intact. Does anyone have any thoughts?

 
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darrell McCoy's Avatar
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03-19-03, 06:30 PM   #2  
darrell McCoy
Sounds like you may need to install a new thermostat.
After reaching an operating temp, it may be weak enough that it is "dumping" the coolant instead of regulating it. Not that common to have a bad sensor. They can be checked by using an ohm meter but you have to know the resistance values. Sensors are not that expensive. If by chance you opt to replace it, careful and do not over tighten it during installation.

 
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03-19-03, 06:39 PM   #3  
Nick68
Thanks for the reply. I probably should try replacing the thermostat. I have not considered it due to the one that is in there now is only 15000 miles old. I guess that doesn’t mean anything though.

 
WeldGod's Avatar
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03-19-03, 09:33 PM   #4  
The sending unit could have been damaged in the swap.

 
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03-22-03, 10:35 PM   #5  
Nick68
Update:
I replaced the temperature switch today and it fixed the problem. Could anyone explain what this “switch” does? I bought a temperature sensor for $17.00 and the temperature switch was $4.00. I installed the switch first because it was cheaper and got lucky. I would like to know how it works though.

 
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03-23-03, 05:06 PM   #6  
Joe_F
One is the coolant temperature sensor which tells the PCM what the coolant temperature is to make air/fuel mixture changes and the other is the sending unit for the dash gauge.

 
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