My son has a 206 with 1.6 liter engine.
It has developed a cooling problem which makes the water temperature gage jump up and down. A 'stop' warning comes up in the display.
The hose from the thermostat housing to the top of the radiator remains cold. The hosed to/from the heater are hot though, so it would seem that the water circulates, i.e. the waterpump is in OK.
Could it be that the thermostatic valve is stuck in the closed (warming-up) position?
Is this an old-fashioned 'self-contained' thermostat, or is it an electric valve actuated by/from a temperature switch or sensor, via the motormanagement system?
Joop Klijn