Temperature gauge reading to low

[Kodjo]

Hi,

My '69 Avanti has a temperature gauge that indicates too low temperatures. I never did see the temperature go above the 150F.

Now, I've got the gauge out of the car. With an 120 Ohm resistor in place, it reads 140F.

There is now a way to adjust it from the outside. So do I have to open it or just buy an other one?

 

Kodjo

Edited December 14, 2023 by Kodjo

[Mel]

The temperature sender on the block is basically a heat sensitive resistor which, as the temperature rises, decreases in value and sends higher voltage to the gauge which is essentially a voltmeter measuring up to 12v.  On a very hot engine, the resistance value drops to 0 ohms allowing full voltage to the gauge which then reads (pegged) hot.  I'd start by replacing the temperature sender, hooking things back up and going from there.  Good luck.

[Dwight FitzSimons]

30 minutes ago, Mel said:

The temperature sender on the block is basically a heat sensitive resistor which, as the temperature rises, decreases in value and sends higher voltage to the gauge which is essentially a voltmeter measuring up to 12v.  On a very hot engine, the resistance value drops to 0 ohms allowing full voltage to the gauge which then reads (pegged) hot.  I'd start by replacing the temperature sender, hooking things back up and going from there.  Good luck.

He might also apply 12V. to the gauge and see if it reads full scale (240 deg.).  In electronics we called that the "smoke test."

--Dwight

[ronmanfredi]

Do you have a thermostat in the engine and if so, is it working?

[mfg]

You might want to check the actual coolant temp with a radiator thermometer..or one of those hand held digital thermo tools.

[Kodjo]

I did replace the temp sender in the engine. That gives the right values, see table below. But, with the gauge on the table, wired up with a variable resistor, the needle does not go to the right value Fahrenheit. So, my conclusion is that the gauge is wrong. I disassembled it but do not know how to adjust it.

.

[Kodjo]

Oh, well, I adjusted the gauge as it seems in order.

Now the values are:

• 220 Ohm -> 150F
• 150 Ohm -> 180F
• 60 Ohm -> 240F

I hope this is right, think so.

 

[Leo B]

To me looks like you have same as mine 1963 Stewart Warner:
From Studebaker Forum:

https://forum.studebakerdriversclub.com/forum/your-studebaker-forum/tech-talk/1822086-resistance-range-for-engine-coolant-temperature-sensor

More:
https://studebaker-info.org/Tech/Text3/temperature_gauge.txt

Was 1965- > different gauge?

Edited December 17, 2023 by Leo B

[Kodjo]

17 hours ago, Leo B said:

To me looks like you have same as mine 1963 Stewart Warner:
From Studebaker Forum:

https://forum.studebakerdriversclub.com/forum/your-studebaker-forum/tech-talk/1822086-resistance-range-for-engine-coolant-temperature-sensor

More:
https://studebaker-info.org/Tech/Text3/temperature_gauge.txt

Was 1965- > different gauge?

Thanks, great info. I think my gauge is now indicating almost the right temperature. 

[pantera928]

On 12/14/2023 at 12:52 PM, Kodjo said:

I did replace the temp sender in the engine. That gives the right values, see table below. But, with the gauge on the table, wired up with a variable resistor, the needle does not go to the right value Fahrenheit. So, my conclusion is that the gauge is wrong. I disassembled it but do not know how to adjust it.

.

So what do these three columns represent? Are these different versions of the gauge for different year cars?

[Leo B]

12 minutes ago, pantera928 said:

So what do these three columns represent? Are these different versions of the gauge for different year cars?

1513321 is GM Gauge Sender Unit. For Studebaker https://mystudebaker.com/electric/tachometer-temperature-senders/

[pantera928]

So are you saying that the Stewart Warner gauges that are used in the original and the Avanti IIs  is expecting a different resistance than it was designed for?

Forgive me for being confused om this. Do we all need to recalibrate our gauges in the Avanti IIs?

THanks

[ronmanfredi]

27 minutes ago, pantera928 said:

So are you saying that the Stewart Warner gauges that are used in the original and the Avanti IIs  is expecting a different resistance than it was designed for?

Forgive me for being confused om this. Do we all need to recalibrate our gauges in the Avanti IIs?

THanks

On my 82 model, the original gauge doesn't have any resistor on it and it dead on with the stock sensor.  It may be that the old style gauge like he is showing are the ones with problems.

 

[Leo B]

1 hour ago, pantera928 said:

So are you saying that the Stewart Warner gauges that are used in the original and the Avanti IIs  is expecting a different resistance than it was designed for?

Forgive me for being confused om this. Do we all need to recalibrate our gauges in the Avanti IIs?

THanks

No. I was trying to make the case that the resistors/senders on the Studebaker Avanti are different than the Avanti II, even though the gauge looks the same. It amazed me. I apologize if I presented the matter unclearly.

[pantera928]

6 hours ago, Leo B said:

No. I was trying to make the case that the resistors/senders on the Studebaker Avanti are different than the Avanti II, even though the gauge looks the same. It amazed me. I apologize if I presented the matter unclearly.

You did not present it unclearly but if the same gauge was being used with sensors of a different resistances, then they would have erroneous readings

[Kodjo]

I'm confused. Avanti II has an chevy engine. My assumptions was/is that they came with a Chevy sensor. So, when the reading was low, I bought a new Chevy sensor but the readings did not change.

Inside the gauge are 2 bi-metals covered with wire. One bi-metal is for the correction of voltage fluctuation, the other goes to the sensor. Is this setup equal to the Studebaker?

I assume the gauge itself is like the Studebaker. My Avanti is from '69 and the S logo is all over the car. Today I found this decode table for SW gauges. My G10 seems to be made in October 1963. This should be according to the Studebaker specification.

Edited December 19, 2023 by Kodjo

[Leo B]

18 hours ago, Kodjo said:

I'm confused. Avanti II has an chevy engine. My assumptions was/is that they came with a Chevy sensor. So, when the reading was low, I bought a new Chevy sensor but the readings did not change.

Inside the gauge are 2 bi-metals covered with wire. One bi-metal is for the correction of voltage fluctuation, the other goes to the sensor. Is this setup equal to the Studebaker?

I assume the gauge itself is like the Studebaker. My Avanti is from '69 and the S logo is all over the car. Today I found this decode table for SW gauges. My G10 seems to be made in October 1963. This should be according to the Studebaker specification.

As I understand it, the gauge and the sensor/sender are pairs. If the motor is different but same gauge, water, volts and wires, I can't find an explanation why the sensor has to be different in terms of resistance. I have a 1963 and a SW G2. Seems you have a similar gauge, I think you need the same level of resistance in the sensor. I can't say if Stude and Chevy differ in sensor attachment or external aspects.
I recommend to call or email https://mystudebaker.com/electric/tachometer-temperature-senders/
I think they know what they sell. #1545220 for your gauge ???
Also note that might be you gauge is not working well.
 

Edited December 20, 2023 by Leo B

[AD]

Kodjo,

Could you please explain how you adjusted the gauge after you took it apart? Is there an adjustment screw or did you have to bend something?

Thanks for all of the data.

[Kodjo]

21 hours ago, AD said:

Kodjo,

Could you please explain how you adjusted the gauge after you took it apart? Is there an adjustment screw or did you have to bend something?

Thanks for all of the data.

You’ll have to get inside. So the glass needs to be removed. Once you are in there, it is adjustable with a screw. You could then modify the housing in a way that the adjustment can be done from the outside. I didn’t…fingers crossed.