If the gauge is normal, then what makes you think it overheats? If you mean the radiator cap boils over, the cap could be defective? There also could be so little fluid in the system that the gauge sensor is not in contact with the fluid, so can't read right. You need to ensure the system is filled, and use a thermometer to ensure proper operating temperature.
Answers & Comments
If the gauge is normal, then what makes you think it overheats?
If you mean the radiator cap boils over, the cap could be defective?
There also could be so little fluid in the system that the gauge sensor is not in contact with the fluid, so can't read right.
You need to ensure the system is filled, and use a thermometer to ensure proper operating temperature.