I have a 1992 740 non turbo wagon with 104k the cars heat level on the dash has always been at about the middle never going past the middle, however yesterday when driving the car after about 30 minute i noticed the needle moving up and the fan came on when i started to drive the needle came back to the middle it happen a couple more times that day but has not happened again.also when i turned the car of that day the needle stayed almost all the way. it looked to me like the car almost over heated. it takes me about 30 minutes to get to work and the the past to days this has not happed again. What can be the problem.

Most of the cars made for Europe are equipped with a( thermostat ) but don`t confuse it with air conditioner thermostat or thing is working like valve that stops water circulating in cold starts so the water will only circulate around the engine block not through the radiator and of coarse it helps heat up your car`s engine faster but the problem comes when that valve got old (by the way most of those valves working as a wax capsule when the water heats to some amount the wax molten so it opens the way for water to circulate through the radiator ) what happens is simply the wax looses some of its function and molten in higher temp . so it block the water again until it heats up to molt the wax my advice : get off that part and just don`t replace it if you found it pricey for you your car still working but will needs more time to warm up i hope i was useful for u sir .