View Full Version : TR2/3/3A electric coolant temp gauge in TR3...

05-24-2011, 07:07 AM
Well, this weekend I installed an electric temp gauge in my TR3. I believe it's out of a TR4. That was the sellers claim. The gauge is a Jeager gauge with domed glass.

My original gauge had given out on me some time back, and this was a much less expensive option for now.

Now my issue is, the gauge does start reading, but it only gets up to midway between the bars on the gauge used to indicate cold and normal operating temperatures.

I know the car always ran at normal operating temp before so I will assume all is ok now.

My question is, can I/should I adjust the gauge in any way?



05-24-2011, 07:18 AM
The TR4 gauge had numbers on the face, not just "cold" and "normal". It can be adjusted, but it doesn't sound to me as though yours needs adjusting. The real question is what does it read just before the engine boils over?

05-24-2011, 08:03 AM
This may take it the other way, but did you install the voltage regulator with the gauge? I believe the gauge runs off 10V, not 12V.

05-24-2011, 11:56 AM

Good catch, you are correct, my understanding was that it ran off of 10V as well so I did install the regulator.


Knock on wood, my engine hasn't been boiling over (that I am aware of) so I don't know the answer to that question.

I'll post a picture of the gauge when I get home this evening.



05-25-2011, 02:27 PM
Not only is the voltage stabilizer important, but the temp sending unit needs to match the gauge model as well.
As Randall mentioned, that early TR4 gauge was full face with temperature number values (90 185 230) and convex glass. The Smiths Jaeger number on the face is BT 2300/OO (for F) If that's what you have, the sending unit for the TR4 that Moss sells is real close. (40 ohms at 185, 20 ohms at 212)

05-25-2011, 11:27 PM
Sorry for the delay. Here is an image of the gauge. Let me know what you think it is out of.

I did make sure I got a sensor for a TR4 so that end of it should be good, I think...

Thanks for the feedback.


05-26-2011, 03:00 AM
There should be some numbers visible on the face (but not in your photo), like BT22nn/nn. Those would help track it down. I've seen that funky pattern of ranges, but I don't recall where. Bugeye, maybe?