Temp Gauge Reads Very High

My temperature gauge has read very high ever since I have had the car. It is a few lines before the red during normal operation but when I look at the engine temp in the climate control it is right around 190/195 and never gets any hotter.

Is there a sending unit that might be bad? Something else?

What climate control parameter are you using? You MUST use the one that's in Celsius (it's either parameter 14 or 24; one of those is mph; the other is coolant temp in C; I forget which one it is). The one that displays F is not what you want. There was a big discussion on the dead forum awhile ago, only the C one gives proper data.

BTW - my wagon reads rock solid 90-91C all day with a new AC Delco thermostat.

I'd have the cooling system temperature checked first; either an infrared thermometer on the radiator or the heater hoses, then decide what to do (whether bad thermostat or bad sending unit).

sherlock9c1 wrote:

What climate control parameter are you using? You MUST use the one that's in Celsius (it's either parameter 14 or 24; one of those is mph; the other is coolant temp in C; I forget which one it is). The one that displays F is not what you want. There was a big discussion on the dead forum awhile ago, only the C one gives proper data.

BTW - my wagon reads rock solid 90-91C all day with a new AC Delco thermostat.

I'd have the cooling system temperature checked first; either an infrared thermometer on the radiator or the heater hoses, then decide what to do (whether bad thermostat or bad sending unit).

Joel,
Just found this:

-08 Coolant Temp (°F) - Reading taken at Cylinder head sensor, typically 20* cooler than the -24 reading
-24 Coolant Temp (°C) - Reading taken at the Water Pump sensor, This is what the PCM uses to control the fans.

...hence the difference. I will check this out tonight. Good thing I have a pyrometer at work!

Thanks!

For the sake of posterity, the LT1 corvettes used a 3-wire (dual output, one ground) temp sensor that mounted to the water pump that gave identical readings to both inputs. Some in the B-body community have installed this sensor in the water pump, put a plug in the passenger side head and then lengthened and rerouted the wire to the water pump so everything reads identical. I've not done this, but it's out there. I don't know if all LT1 vettes had it, but certainly some years did.

After using the water pump sensor input in the climate control I am getting 101 degrees C which is 213.8 degrees F.

Using the pyrometer I measured about 170-175 degrees F at the water pump on the hose going from the pump to the radiator.

Does this mean I have a 180 degree thermostat and the sending unit is wrong?

With the car warmed up, idling in Park, with the heater on full blast for at least one minute, shoot the pyrometer into the heat duct. What do you read?

I just want to get a second opinion on cooling system temp.

sherlock9c1 wrote:

With the car warmed up, idling in Park, with the heater on full blast for at least one minute, shoot the pyrometer into the heat duct. What do you read?

I just want to get a second opinion on cooling system temp.

Just so I am clear, you are referring to the heat duct in the car, correct?

Yes. If the car really is running at 210, you'll see it at the heater output on the floor. Once the car hot idles for a minute with the fan on, the heater ducts should equalize at whatever temperature the heater core is at, and give you a good reading.

Again, this is to get a second opinion before you start spending money on stuff.

sherlock9c1 wrote:

Yes. If the car really is running at 210, you'll see it at the heater output on the floor. Once the car hot idles for a minute with the fan on, the heater ducts should equalize at whatever temperature the heater core is at, and give you a good reading.

Again, this is to get a second opinion before you start spending money on stuff.

Floor vents are right around 155-160.