I'm not familiar with you car, but in most MBs it is normall to get 100 - 110C. Does your car have some aux fans in front of the radiator? Aux fans usually turn on at low speed when A/C is on and on high speed when coolant temperature is about 103C.

Check also if your main fan is good. Some have a fan clutch that needs to be checked for good operation but I'm not familiar with your car model.

Radiator cap is very important and is a cheap fix. Check if the seal is in perfect shape.

When you fill the system with coolant, some air can be trapped inside the system. Let the engine run for about 10 minutes with the radiator cap removed to let the air out.

It is recomended to change the coolant every 3 years. It is better to use the yellow MB or Zerex stuff, mixed 50/50 with destilled water. I can get those coolants in my country, so I have to use a different one.

If you don't have coolant leaks, then the water pump is probably good.

Just some ideas. I hope this helps.

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Juan
1995 E320 Sedan
2008 Ford Escape
RC Helicopter