Engine (cooling) problem on Audi 80 '86

For a while my Audi has been overheating a bit. The temperature gauge is between 95C an 100C. It is normally stable at 90C. The temperature quickly goes up in city traffic. I thought it was the thermostat and
planned to replace it this weekend. This morning when I started the car the generator and the cooling warning lamps did not go out. The generator belt was not broken, though a little slack. I tightened the belt and after that the warning lamps did go out. After driving about 15 km the generator warning lamp suddenly started blinking. At the same time the temperature dropped and I had a vague feeling that something smelled like it was burned. I stopped the car and checked the generator belt. It was still tight. Aftar a couple of minutes I decided to drive home again. Now the temperature was between 85C and 90 C. When I came home I noticed that one fuse was blown, but it was just a small fuse for the parking light, so I don't think it is related to the other problems. Anyone have an idea of what can be wrong? The engine is quite old (over 560 000 km) so maybe it has done its duty and should be replaced?
Thanks /Sven
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Sven Agardh wrote:

When was the last time you changed the water pump?
Cheers,
C
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Chris Mauritz wrote:

Both the water pump and the radiator was replaced less than 6 months ago.
/Sven
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Sven Agardh wrote:

Is the radiator fan coming on?
cheers,
C
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Chris Mauritz wrote:

I can't recall hearing the fan for a while. I haven't checked if it is working.
/Sven
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Sven Agardh wrote:

Start it up and let the car idle while parked. When it reaches normal operating temperature, the fan should come on. If it doesn't, there's your problem. If that's the case you then move on to checking the fan relay and the fan motor itself.
Cheers,
C
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I thought the fan was not used under normal conditions. As long as I have had the car the fan has just been used when the engine was hotter than normal like in heavy city traffic.
/Sven
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Sven Agardh wrote:

No, the fan should definitely come on when the car is idling after 5-10 minutes since there is no airflow through the radiator (when the car is not moving) without it. I suspect this is your problem and explains why the engine runs hot in city traffic.
Cheers,
C
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The fan motor may have siezed bearings and that load caused the fusable link to blow out (if you have one). If you don't it probably fried the wiring and caused the smell and alternator loading. It happens often when miles get up there.
Tony '91 100Q 5spd
Chris Mauritz wrote:

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