vauxhall astra 1.6 8v club

[sparkysteve]

why does my temperature gauge fluctuate so much. When i set off from cold the gauge seems to take along time to start moving when it does move it rises to 80 then drops right back down again straight away. Once the car has run for a while the gauge varies all the time rising after going up hills then falling back down after going down hill

[woodchopper]

Sounds liie a faulty thermostat - the reason it goes up after you climb a hill is that you burn more petrol to go up a hill than yo do when you are going down one - the Vauxhall Corsa up to year 2002/3 were noted for faulty thermostats - maybe the astra has the same problem - oterwise could be a faulty sender unti.
Average running temp should be betwenn 88-94.
My bet is on the thermostat though.

[edd2blue]

might be air locking also check u have the right mixture of anti freez to water recomended for ur car other wise sparkysteve is on the right track