5 replies to this topic

[midwestmini]

Does anyone know what resistance this sensor should read at room temperature.

Any thoughts on where can I buy the replacement Unipart GTR101, GTR102 or GTR143 temperature sensors here in the USA? What is the difference between these part #s? I think the GTR101 is normally used in most engines.

I think my old Smiths Industries took a dive (now reads 1/4 gauge when cold and Hot when Normal).

EDIT- Found this out on the web during the wee hours of the night:

GTR102 TRANSMITTER, water temperature 1961-64.
GTR104 TRANSMITTER, water temperature 1964-69.
GTR101 TRANSMITTER, water temperature 1969-85.

Found some replacement part #s for GTR101 at the NAPA website:
PART # ATM 1434031 ($10.50)
PART # BA 2011112 ($23.99)

I guess I answered 1/2 of my own question, but its always good to share the results regardless!

Edited by midwestmini, 14 September 2007 - 05:34 AM.

[dklawson]

This topic comes up periodically and I have yet to hear a definitive answer. No one seems to be able to match gauge numbers to sending unit numbers.

I can tell you that the 102 transmitter you list for up to 1964 would be slightly different than the other two in that it would be designed for cars without the voltage stabilizer. So, if your car was built AFTER September 1964, use one of the other two senders. I'm sorry, I don't know what would distinguish the other two. Frankly I would have expected a later transition date between them... perhaps associated with the change to the Nippon Seki instruments... but this doesn't appear to be the case.

[Ethel]

This topic comes up periodically and I have yet to hear a definitive answer. No one seems to be able to match gauge numbers to sending unit numbers.

I can tell you that the 102 transmitter you list for up to 1964 would be slightly different than the other two in that it would be designed for cars without the voltage stabilizer. So, if your car was built AFTER September 1964, use one of the other two senders. I'm sorry, I don't know what would distinguish the other two. Frankly I would have expected a later transition date between them... perhaps associated with the change to the Nippon Seki instruments... but this doesn't appear to be the case.

Could the change be related to different thermostat ratings - a quick fix to keep the gauge reading normal with a higher running temperature?

[dklawson]

The sender change would not be associated with changes in the thermostat.

All Smiths gauges I've looked at on the bench show a mid-range "normal" reading near 185oF (as long as they are using correct sending unit). This has been true even when comparing mechanical gauges and electric ones.

It's more likely that the sending unit changes are associated with resistance range changes on the gauge end of things. Why the gauge would change is beyond me.

Edited by dklawson, 14 September 2007 - 05:54 PM.

[midwestmini]

I got the rest of my question answered.....

Here is a link on GTR101 equivalent sensor listed by MOSS in this MG website. I just used the site for the sensor resistance reference at 100degC and 25degC.

http://www.mgcars.or...auge/sender.pdf

Attached Files

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Edited by midwestmini, 15 September 2007 - 01:46 AM.

[midwestmini]

For what its worth, don't monkey around with old temperature sensors.

Even though you think they may read right - always buy a new sensor if you remotely think that your old sensor is bad.

I convinced myself my old one way okay by testing it on the stovetop (as shown above) and was at the point of replacing water pump, radiator etc. before I decided on a whim to just try and replace it with a new sensor (Unipart #GTR101 or from Napa the equivalent is #ATM1434031).

I went from a state of paranoia believing the engine was overheating (gauge just hitting the red) to seeing the gauge back down in the normal (1/3 to 1/2 temp range) after a new sensor was installed.

Back on the road again....ahhhhhhhhhhh.