The part with the wax in it is just to the right of the spring in your photos. It is the piston in a sleeve. Walt is absolutely correct.

Otto

Make sure that your temp sender matches your gauge, not necessarily your engine. If it was correct with your 3.0, then that is the sender you need.

Thanks for all your input.

I have finally got some time at home to investigate further.

I purchased a electronic steak thermometer for use when determining the temp of food. But I had other intentions for it. I just put the meter pin right down into the oil tank when I had warmed it up a bit. When the temperature reached 88 celsius, I felt the pipes going to the front heat up. So, the external thermostat works after all. I then checked the part number for my new temperature sender. It turns out I have the wrong sender. I have the one for numbered gauges, not for my gauge without numbers on it.

So that was good news! :)
I just need to replace the sender, -a walk in the park... :cool: