High Water Temperature: Causes & Solutions

Hello,
"On my Audi 80 TDI with 90 horsepower and 290,000 km, the water temperature during normal driving is always around 100°C, often higher, and sometimes even reaches 110°C. The second stage of the radiator fan is almost always running. Previously, the operating temperature was always around 90°C, and it has gradually increased over the years. I assume the temperature gauge is accurate, because the thermostat switch activates the first stage of the radiator fan at approximately 95°C and the second stage at approximately 102°C. It's unlikely to be the thermostat of the water pump, because the radiator gets so hot that the thermostat switch in the radiator activates. The water pump was replaced about 2 years ago (without a thermostat). Could it be that the radiator is partially blocked (e.g., due to scale buildup)? Has anyone else experienced the same problem? I'm worried that this temperature will cause my "old car" to have a "heart attack"."

It sounds like you're saying: the engine's cooling system isn't working properly; the cooling capacity of the radiator is insufficient. Check the temperature. Add coolant or replace it.

Often, even in vehicles with air conditioning, with this kind of mileage, the air conditioning condenser (radiator) and the water cooler become so heavily soiled that heat can hardly be dissipated. This is easily checked by loosening the condenser bracket and tilting it slightly forward to see if it's heavily soiled. This is especially common in vehicles that are frequently driven on high grass. If not, I agree with my predecessor.

How about the heating capacity of the heating heat exchanger?
Should the temperature (approximate value) be measured at a minimum of 70°C?
At least at the medium blower setting.
the outside temperature.
fast engine speed,
Cooling water temperature: minimum 85°C.
If it's also cold, meaning 40-50 degrees Celsius, then rinse it.
If it's overheating, the engine radiator might be clogged internally or externally, as mentioned above.

Hello,
First of all, thank you very much for the answers.
I've decided to install a new cooler.
I don't think much of the radiator cleaner.
"The cooler costs €125 including shipping, and it's supposedly the same quality as the original."
I'll let you know if it really was the cooler.

Best regards,

Hello,
How was the problem resolved? Did the new cooler fix the issue?

Hello,

I installed a new water cooler today.
Now he has a normal temperature again.
The old one contained a brownish broth.

I hope you flushed it with some cleaner. The rust-colored liquid can also get into the radiator!

...and rinse it the other way, so that the sludge also comes out.

Best regards, Rainer.