Hi Hans,

Actually, it looks like I was partly mistaken. I didn't realize you had
a Syncro.
It looks like it is located where I said it is, but it may be a one wire
sensor. I just looked at my Bentley and it shows it on page 19.11 (Fig.
19-427), under Engine-Cooling System. Bentley calls it "Temperature
sender coolant display".   I had to replace mine a couple of months ago.
On mine, I had a metal clip (probably green) that I pulled out and then
it was a piece of cake. Be ready for some coolant to come right to your
face when you remove it...  :-)  Make sure you clean the terminal(s).

If it is the Instrument Voltage Regulator/Stabilizer on the dashboard,
check page 90.8 (Fig. 2), under Electrical System-Instruments, Radio.

Best of luck!

georgios