I'm the new owner of a '96 960 wagon. The car has 150,500 miles on it and has been very well maintained. No issues when I got the car ~500 miles ago. I'm now having a significant problem with the cooling system.

The symptoms...

Yesterday, I noticed after driving at highway speeds for an hour or so that the temp gauge was climbing higher. I kept a closer eye on it and it seemed to oscillate slowly back and forth in the upper half range, approaching the red zone. It climbed higher and higher and eventually pegged at red. No coolant leaks. Heat worked fine. Electric fan (behind radiator) worked fine. Car drove fine. Gauge stayed all the way over to red.

I was pretty far from home, and far from my garage. I self-diagnosed a stuck thermostat and went to the local NAPA store (no Volvo dealer for >50 miles) and bought a thermostat and tools. I couldn't get the thermostat housing loose despite proper Torx bit and by this time I suspected that maybe the car wasn't running hot at all. Upper radiator hose warm; lower radiator hose cold with gauge still on red. I decided to chance it and keep driving the car.

I noticed that after having it parked while we ate in a diner (~an hour or so), on start up it went over to the middle and then 'jumped' all the way over to full red. It went back and forth a few times. Sometime after that the 'Check Emgine' light came on and stayed on. I've also noticed that the electric fan is constantly running now, something I don't believe it did before today. It might be my imagination, but it seems louder and more noticable than it used to be.

I drove the car back home today, 70 miles, and for the entire time the car drove like a charm, the temp gauge stayed right in the middle where it belongs but - the check engine light is still on and the fan keeps running.

I'm not too enthused to hand this car over to my mechanic, whose electrical diagnostic skills are marginal at best. Does the above description match a specific 960 syndrome?? If so, I'd be very grateful to have an accurate diagnosis before we start changing out different bits to see what happens.

Sorry bout the long post. Many thanks for any suggestions.

Kai S
'67 Duett and '96 960 and assorted non-Volvos.