I too have the same problem, a 1997 1.4 Astra. Running hot for the last couple of weeks. No disernable reason. Coolant and Oil levels are good but fan kicking in after 20min on the the motorway (60-70mph). Less of an issue around town. Seems a bit opposite to the norm? Never used to be an issue. If anything it always ran cooler than it should.

Any Astra guru's out there with answers or suggestions for MrD and myself?

Any pointers gratefully received.

Phil

Can you cool it by putting the heater on full? You should get loads of really hot air from it. If not, the water isn't circulating properly. In my son's 12yr old Citroen Xsara this was a gradual onset problem with no loss of coolant, apart from the occasional steam overflow when it got too hot. I suspected water pump failure and took a punt on a repair. Sure enough, all the plastic vanes had disappeared leaving just the metal flanges rotating uselessly. Perhaps your pumps are of similar design.

I'm surprised this problem isn't mentioned more frequently on this site - there must be loads of 10yr old cars out there with this sort of failing water pump. Perhaps they don't catch it in time and the head gets too hot.......warps.......sc*** car. Or even misdiagnose it as head gasket failure - ......and sc*** the car.