I guess I have to take the car to the shop but I'm curious about what you have to say about the cause of this problem.

While driving the temp gauge suddenly quite quick went up to the highest temp and the warning sound and lamp came on.

I immediately pulled over and opened the hood. The fans were at full speed, never seen them run so fast.

The coolant water level was normal in the container and I couldn't see anything unnormal. I touched the hoses but couldn't tell if they were warmer than normal.

At idle the temp went down but when start driving the temp went up again. I drove carefully and sometimes the gauge was going down a bit but rose again.

I tried to cool of the water by setting the heat of the air in the compartment at max but it came only non heated air!

What do you think is the problem?

The thermostat?

I replaced it barely 4 years ago. Has it been broken again?

I have googled and found that there are two plastic arms (see picture) that holds the thermostat in place that often breaks and the thermostat comes of its position.

 

Edited 1 May, 201511 yr by rail

Check that the water pump is working as it not unknown for the blades to break. 

With the engine only warm, release the header tank top (slowly to release any pressure) then rev the engine a bit. You should see water coming into the tank. If not then probably failed water pump.

Shouldn't it make some noise if the blades on the waterpump breaks?

Edited 1 May, 201511 yr by rail

Sometimes on the 1.8t engines the impeller can become detached from the shaft through prolonged use.  When was it last changed?

Sometimes on the 1.8t engines the impeller can become detached from the shaft through prolonged use.  When was it last changed?

I have a Skoda Octavia Ambiente 1.6 2002.

I have never changed the waterpump. I thought I should change it when I replace the timerbelt soon.

The car have gone a little more than 100 000Km.

Thermostat stuck closed or water pump failure. Very similar symptoms on one of my parents' old cars with a 1.9 TDI engine. Engine temp shot up - no unusual noises. In my experience of two failed thermostats on different cars they both stuck open, so I would suspect the water pump failure is more likely.

 

Shouldn't it make some noise if the blades on the waterpump breaks?

Not necessarily if it fails in the way that Liverpool-Lad says. Plastic impeller water pumps are designed to fail in this way if the coolant freezes to avoid wrecking anything else.

Sometimes on the 1.8t engines the impeller can become detached from the shaft through prolonged use.  When was it last changed?

 

 

I have a Skoda Octavia Ambiente 1.6 2002.

I have never changed the waterpump. I thought I should change it when I replace the timerbelt soon.

The car have gone a little more than 100 000Km.

I've known that happen on a TDi; no abnormal noise, just overheating.

 

It's not unusual to treat the water pump as a service item because if you don't change it with the timing belt its MTBF is about 1.5 timing belt changes, and it costs as much to change as the timing belt.

Might be worth bringing that cambelt/pump work ahead!

Water pump. Had this on mine. The impeller had split so it couldn't make full contact with the shaft anything above idle speed.

Dont drive the car until you replace the water pump, if the thermostat was at fault you would have hot air at the heater.