The coolant temp gauge on my Mi16 has started reading very low - just in the past two days.

Previously it would read 80degC on the open road - nice and normal.
Now it reads below 70degC, but warms up to 80degC or beyond if the car sit idling for 5-10mins. Coolant level is fine.

Where should I look:
* faulty/jammed thermostat?
* loose wiring?
* something else?

Keen to hear suggestions - thanks!!

UPDATE:

Have spoken with 3 or 4 people, including my long-time mechanic (who knows this engine in Citroen guise). Almost 100% certain the problem will be a faulty thermostat - so car is booked in for a new thermostat and a complete flush-n-fill of new coolant.
-prc.

UPDATE 2:
problem fixed - new thermostat fitted. Also flushed coolant system and refilled with 50/50 mix of antifreeze and water. Took the opportunity to fit one of Peter Taylor's inlet cam offset keys while the car was in being serviced.

The key and the 7500 chip make a noticable different (better!) through the mid-range. yay!

Have you got the 3 row ecu? I tried the chip on my 2 row and it didn't alter the limiter sadly.

Indeed. The ECU in my car is a 161 (3-row). Note I haven't tried the limiter - I generally change up at 3500rpm, or 4500rpm if I'm having fun. Very rare for any of my cars to see the high side of 5000rpm.

Chip provided by Peter Taylor of Sydney, Australia. You can reach Peter and read about his work on the 1905 engine at www.taylor-eng.com (no affiliation, except I'm a happy customer).

-prc.

I say hello to the rev limiter if I'm having fun.

I generally stop before that... just. 1.9 16v, it all happens up top