Coolant Temperature Sensor

Zip

Member
35
8
8
My water temp gauge is reading low so I was thinking of replacing the water temp sensor. According to my Haynes manual, " If a temperature gauge is included in the instrument cluster, the temperature sending unit is replaced by a transducer." Is this a different sensor entirely from the non-gauge-equipped sending units? The on-line parts places don't differentiate.....
 

cammerjeff

Active member
748
50
28
Belleville MI
Yes,

The non temp equipped cars use a simple on/off switch to power the idiot light. When the engine temp reaches the predetermined level, usually around 230F, it sends power to the light.
If you have a gauge a simple on/off switch will not do. So they use a transducer to very the signal (microvolts usually) with temp changes to move the needle in the Gauge.

What year is your car? and what engine does it have? Maybe we can help you find one.
 

92 Sunbird LE

Well-known member
2,345
62
48
Salinas, Puerto Rico
Most of the 4 cylinder 88 - 94 clusters have a guage so it's just one sending unit. ( Due to head casting problems) V6 not sure.... I looked up a 1987 on Rock Auto and it shows 2 sending units.

Doug in P.R.:cool:
 
Last edited:

cammerjeff

Active member
748
50
28
Belleville MI
I looked up a 1990 Sunbird with the 2.0 N/A engine on Rockauto and they list both types of Temp Sensors. Before buying a sensor, I would try cleaning the wiring connection on the temp sensor, also what do you mean by "reading low" has it always read that way, or has it recently changed? Is the upper radiator hose getting warm to the touch after then engine has warmed up? Does the heater put out the same amount of heat it used to?

It could be your thermostat is not working properly, maybe staying slightly open all of the time.

______________________________
 

Zip

Member
35
8
8
Yes,

The non temp equipped cars use a simple on/off switch to power the idiot light. When the engine temp reaches the predetermined level, usually around 230F, it sends power to the light.
If you have a gauge a simple on/off switch will not do. So they use a transducer to very the signal (microvolts usually) with temp changes to move the needle in the Gauge.

What year is your car? and what engine does it have? Maybe we can help you find one.
I've got the 3.1 V6 in my 1991 convertible.
 

Zip

Member
35
8
8
I looked up a 1990 Sunbird with the 2.0 N/A engine on Rockauto and they list both types of Temp Sensors. Before buying a sensor, I would try cleaning the wiring connection on the temp sensor, also what do you mean by "reading low" has it always read that way, or has it recently changed? Is the upper radiator hose getting warm to the touch after then engine has warmed up? Does the heater put out the same amount of heat it used to?

It could be your thermostat is not working properly, maybe staying slightly open all of the time.

I cleaned the sensor connections - the gauge doesn't rise much at all - the car heater is pumping warm after about 5 minutes of running. I've only had the car a couple of months and it's always been that way. The Check Gauges light has always been on. All the other gauges are reading normal. It's only got 33k miles on it...3k of which I've put on it in the last month or so.....
 

Zip

Member
35
8
8
Yes,

The non temp equipped cars use a simple on/off switch to power the idiot light. When the engine temp reaches the predetermined level, usually around 230F, it sends power to the light.
If you have a gauge a simple on/off switch will not do. So they use a transducer to very the signal (microvolts usually) with temp changes to move the needle in the Gauge.

What year is your car? and what engine does it have? Maybe we can help you find one.
1991 with the V6.
______________________________
 

Zip

Member
35
8
8
I think I see which sensor it is with the gauge - my Haynes manual showed where it was. I needed to search for Sender versus Sensor! Silly me. It appears to be the one with the green wire coming off it on the RockAuto site.
 

Zip

Member
35
8
8
Changed the one sensor last weekend. The gauge is still reading low....going to change the thermostat tomorrow....we'll see!
 

Zip

Member
35
8
8
Changed the thermostat, no difference in temp gauge reading - still reads low - gets to about 1/2 way sitting in traffic not moving for 1/2 hour then down to just off the peg once we're moving again. Check gauges light stays on all the time. Might be time for the old 70s repair of putting a piece of black tape over the check gauges light....LOL
______________________________
 

melsg5

Staff member
SUSTAINING MEMBER
22,508
316
83
What temperature thermostat did you buy?
Do you have the old thermostat?
If you do suspend it in a pot of water and slowly bring it to a boil.
The thermostat should remain closed until shortly before it starts to boil.
When the gauge is reading just above the peg is the engine cooling fan running?
 

92 Sunbird LE

Well-known member
2,345
62
48
Salinas, Puerto Rico
Mine only goes to a 1/4 on the guage all the time with no thermostat, so half ain't bad ......,it's bad when it's 3/4.

Doug in P.R. :cool:
______________________________
 

Zip

Member
35
8
8
And the other question I asked about the fan?
And the question I asked about the old thermostat?
Oops, forgot to check the fan....will do later. I tossed the old thermostat. Gauge was reading 1/3 this morning on the commute - slightly higher than before I changed the thermostat. Maybe something else had set off the Check Gauges light....the other three gauges are in their "normal" range though.....
 
Top