Sharan water temp gauge "hunting"

[sharansporttdi]

Noticed this tonight on the way home from work. Normally, when warm, the water temp gauge is vertical (90 degrees) and stays at this indefinately. For some reason, the gauge dropped down to 60 then increased again to 90. This happened again once at 90, and kept doing this for approx 10 miles. My speed was a constant 60mph:aargh4:

I stopped the car for 15 mins (went to the shops) and drove home without further occurrences. Outside temp was hovering around 4.5 degrees.

I will check the water reservoir tomorrow in the daylight, and also the oil filler cap. Is this just a glitch or am I on the verge of a head gasket failure??

Has this happened to you, and if so, what was the cause

[kite]

could be a failing temp. sensor or a failing stat.

[sharansporttdi]

Still not got round to sorting this out yet. In a bid to try and diagnose this, when the temp gauge was fully left (60 degrees) with the engine warm, I turned on the air con and selected the HI setting. Within moments, the temp gauge went to vertical (90 degrees) and was blowing nice and hot.

Is this a thermostat problem more than purely an indication problem??

Ta muchly