Lotus Elan

Temp sender fitting

PostPost by: rdssdi » Sun Nov 02, 2014 9:50 pm

I have tried for years to get my temp gauge to approximate the actual coolant temperature.

I replaced my original gauges with new Smiths classic gauges as the originals were beyond repair.

The temperature gauge is Smiths (Caerbont) P/N BT2204/00B.

The sender that I believe matches that is TT380300. Caerbont says they use the TT681101. They are checking the respective ohmic values. I am currently using an Intermotor P/N GTR120 which is said to match the TT681102. The gauge presently reads 10 to 15 C high.

From my brief experiments I consider the GTR110 (interpart) a closer ohmic range. Unfortunately that is a 5/8-18 thread. It appears that the present sender, a 1/8-27 npt thread, fits into a fitting which screws into the block and appears to be the 5/8-18.

Has anyone successfully removed this fitting from the block without damage to the head?

Picture attached.

100_2299.JPG and
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PostPost by: gus » Mon Nov 03, 2014 2:37 pm

the gauges can be re calibrated with a special smiths box that are around ,I have never done it or had it done, and my gauge reads virtually identical to a digital rtd gauge in the radiator
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PostPost by: RichardHawkins » Mon Nov 03, 2014 6:35 pm


My car is a 1968 S4 Elan. I measure the thread into the head that you refer to as, 3/8" NPT, which is 18 threads to the inch and very close to 5/8" O.D.

My Elan has different temperature gauge arrangements, but has an adaptor that screws into the head, and unscrewed OK.

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