[jhv48]

Don't rule out a stuck thermostat as well.

What does the water temp gauge show when the engine overheats?
Are the fans running at that time?
If the fans are not coming on when the temp gets over 100 Celsius, feel the radiator hoses going to and from the radiator. Are they hot? If not, your thermostat is stuck closed and no water is circulating through the radiator. Simple and cheap fix.
If the hoses to and from the radiator are hot to the touch, the fans are on and it still overheats, take it to a mechanic. Sum ting Wong!