diagnosis/series of unfortunate events

Been driving this 1992 940 wentworth for 3 years with no major problems, so really can't complain, but recent events have me wondering, how long can this hero of a car carry on, and at what cost? Any general feedback very welcome. Recent work: new head gasket, thermostat, exhaust. (Suspected leak in heater matrix or heater valve, under investigation, with help of forum members, thanks.) Car was running well. THEN, rubber hose burst while driving, left not a drop of water in resevoir. Feared head gasket wrecked again. Hose now replaced. But temp guage is juddering, on acceleration, and rising and falling at it's own will. Also exhaust warning light on dash lit up. Whats going on guys?

Airlock in the cooling system maybe?

:):)As stated possible air lock or thermostat now faulty after overheat

thanks v much for that. next question, is it safe to drive? and how'd you deal with an airock, like is it a case of bleeding it like central heating airlocks? Time of year, no mechanics available. Guage is settling at lower end after driving for a while.

Make sure you're not low on coolant. Does the heater blow hot? Do you know how to swap the thermostat? There are many posts on this thread re warning lights. I think your car has the same diagnostic system as mine - a little black box under the bonnet with a probe, some sockets, a pushbutton and a LED. You can use this to read any fault codes (and reset some of them, including the lambda - exhaust - light). Do some searching and you should find the info - let me know if you can't.

Thanks you guys for help clear confusion. Car still drives well, unbelievably. Engines must be very hardy on these things because have put mine through hell. Havn't had time to deal with LED box but yes, at least it is clear now what must be done. temp guage must be banjaxed from last overheating episode, as not moving any more, at least they are not too expensive. support from site invaluable, double thanks to all.

I think it's more likely to be the temperature sender than the gauge itself.

I have a 940 turbo which recently overheated and now won't start (See my thread ) I am curious to know how much your head gasket replacement cost, assuming you had it done at a garage. I may have to take the plunge and cough up for this if I can't find out what else could be causing the engine to resist starting.