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Author: Subject: Temperature sender help
cliftyhanger

posted on 11/4/21 at 07:26 AM Reply With Quote
Temperature sender help

I have an ST170 in my Spitfire (car, not plane before anybody asks)
I am using the std plastic thermostat housing, probably from an early blacktop zetec. The temp sender for the gauge has always read low, so normal running sits at 1/4, 95 degree fan switch cuts in when the needle is bang in the middle.
However, the sender got damaged, tried a replacement one for an blacktop, and before the engine is running it reads 1/4, rising to full scale within minutes.
So either a faulty sender (it is reading only 40ohms at 80 degrees, which is low) or the old one is a mystery.

What I really want is to get a sender that matches the std spitfire type, used on many 70's british cars. The gauge is a Lucas one, running on a 10V stabilised supply. The usual sender is GTR108. This has a resistance of 100ohms at 90ish degrees. I don't think an adapter would work well, as it would need to be long so (a) may not physically fit and (b) would be slow to respond or give false low readings.

What I am after is a sender, 1/8npt thread to fit the thermostat housing, and with a resistance of 100ohms at 90 degrees. A chart or table would be handy....

Any pointers? Ta

(meanwhile I have bodged the damaged sendet by soldering flyleads to the broken connectors, not terribly satisfactory)

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40inches

posted on 11/4/21 at 09:19 AM Reply With Quote
Would this one work? https://www.carbuilder.com/uk/temperature-sender-1-8-npt
Or this https://rimmerbros.com/Item--i-GTR108

[Edited on 11-4-21 by 40inches]

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cliftyhanger

posted on 11/4/21 at 10:35 AM Reply With Quote
quote:
Originally posted by 40inches
Would this one work? https://www.carbuilder.com/uk/temperature-sender-1-8-npt
Or this https://rimmerbros.com/Item--i-GTR108

[Edited on 11-4-21 by 40inches]


Sadly the CBSone has too high a resistance, so will under read. (seems most modern engines use high resistance from the few details I have found)

And teh GTR108 is the right sender, but has a chunky 5/8unf thread so too big. I have one here, I am tempted to butcher it as the threaded nut section is steel, and looks like it may be a "sleeve". If I carefully cut it off I may, just may, be able to epoxy the sender part into a drilled-out 1/8npt sender. What can possibly go wrong??

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40inches

posted on 11/4/21 at 11:26 AM Reply With Quote
quote:
Originally posted by cliftyhanger
quote:
Originally posted by 40inches
Would this one work? https://www.carbuilder.com/uk/temperature-sender-1-8-npt
Or this https://rimmerbros.com/Item--i-GTR108

[Edited on 11-4-21 by 40inches]


Sadly the CBSone has too high a resistance, so will under read. (seems most modern engines use high resistance from the few details I have found)

And teh GTR108 is the right sender, but has a chunky 5/8unf thread so too big. I have one here, I am tempted to butcher it as the threaded nut section is steel, and looks like it may be a "sleeve". If I carefully cut it off I may, just may, be able to epoxy the sender part into a drilled-out 1/8npt sender. What can possibly go wrong??

Can you drill and tap, 5/8unf taps are cheap as chips?

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obfripper

posted on 11/4/21 at 12:01 PM Reply With Quote
Is your gauge a rebadged vdo or smiths, if so it will point at c with 240ohms and h at 20ohms, a smiths or vdo sensor should work here as they have the same resistance curve, something like these:

https://www.merlinmotorsport.co.uk/p/vdo-water-temperature-sender-1-8-npt-thread-323801005001

https://www.merlinmotorsport.co.uk/p/smiths-temperature-sender-1-8npt-cb-ts-18

There's cheaper copies on ebay with a threaded terminal that appear to be compatible, but you take your chances there.

https://www.ebay.co.uk/itm/Oil-Water-Temperature-Gauge-Sensor-Temp-Sender-1-8-NPT-Smiths-VDO-Autometer-G/322480123346

Dave

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r1_pete

posted on 11/4/21 at 01:01 PM Reply With Quote
I've just done the same thing in my Mustang.

I used a Ford 3.0 V6 sensor with a 1/8 npt thread, and a 1/8 to 3/8 npt adapter, it works perfectly with the 10v Smiths gauge, which is the same as the Jeager unit in your Triumph.

You would need to add a ground wire to the body of the sensor if using it in plastic.

https://www.ebay.co.uk/itm/TEMPERATURE-SENDER-ADAPTOR-3-8-NPT-MALE-X-1-8-NPT-FEMALE-IN-BRASS-/123798100468?_trksid=p2349624.m46890.l49286

https://www.ebay.co.uk/itm/NEW-RELIANT-SCIMITAR-GTC-GTE-TEMPERATURE-TRANSMITTER-/163770389995?_trksid=p2349624.m46890.

[Edited on 11/4/21 by r1_pete]

[Edited on 11/4/21 by r1_pete]

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cliftyhanger

posted on 11/4/21 at 06:36 PM Reply With Quote
quote:
Originally posted by r1_pete
I've just done the same thing in my Mustang.

I used a Ford 3.0 V6 sensor with a 1/8 npt thread, and a 1/8 to 3/8 npt adapter, it works perfectly with the 10v Smiths gauge, which is the same as the Jeager unit in your Triumph.

You would need to add a ground wire to the body of the sensor if using it in plastic.

https://www.ebay.co.uk/itm/TEMPERATURE-SENDER-ADAPTOR-3-8-NPT-MALE-X-1-8-NPT-FEMALE-IN-BRASS-/123798100468?_trksid=p2349624.m46890.l49286

https://www.ebay.co.uk/itm/NEW-RELIANT-SCIMITAR-GTC-GTE-TEMPERATURE-TRANSMITTER-/163770389995?_trksid=p2349624.m46890.

[Edited on 11/4/21 by r1_pete]

[Edited on 11/4/21 by r1_pete]


Brilliant, found a proper Lucas (red packaging) one, should be here later in the week. And my spit has Smiths gauges, so from a late car.
Many thanks to all...

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ian locostzx9rc2

posted on 11/4/21 at 07:56 PM Reply With Quote
Speak to the guys at etb instruments there very helpful
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