[fortyonerag]

There are two sender units on the 41, one in each head. They are linked together.

One provides the over temp indication - full scale deflection on engine overheat. It has two terminals and is on the drivers side (I think).

The one on the passenger side (I think) provides the actual temp reading.

Disconnect the line from the gauge to the drivers side sender unit and earth it. You should get a deflection on the gauge. This will indicate whether the gauge is working.

I'm not immune to memory fade, so if someone says I'm in error, fair enough.

Being a braces and belt type of guy, I installed a pair of SW mechanical gauges. Apart from more accurate temp reading, I have much better oil pressure than I thought!