Modern Vespa

Hello

On a 2009 VESPA 125 GTS IE, I have a systematic overheating problem every time I start it.

Here are the symptoms:

1. After a few minutes, the temperature rises,
2. The fan starts,
3. The orange light flashes,
4. The needle rises to the red line, then the orange light goes out,
5. The temperature drops back to normal throughout the ride.

What's been happening since today is that I have coolant coming out of the expansion tank, visible on the footwell, because I think it must be boiling.

12,000 km service done a month ago, coolant level OK.

The Piaggio dealership near me kindly told me it was normal; a Vespa gets hot

Do you have any diagnostic ideas?

Sincerely,

David

I expect you are driving the GTS during the symptons you describe:

1) That is normal
2) Not normal. While driving the fan should not come on, unless it is a very hot day and you are on a very steep and long climb, or unless you are in a traffic flow moving forward at pedestrian pace.

It sounds like the thermostat is not working properly, does not open properly.
Then you describe 5)
That can be interpreted as the thermostat not fully stuck but needs way to high temperature to finally react.

Peter's theory of the thermostat sounds plausible.

agree possible t-stat and possible air in the system. Also you could have a crack hose causing the leaking coolant on the floorboard area.