4AGE 16V engine overheat when at high speed

[Dave W]

If you are not seeing any change in the water level of the over flow tank, that would lead me to think that it probably the radiator. [ you would have a very small leak with no level change ] You could try cleaning the fin area with compressed air or water, then straightening any bent fins, but you are more likely going to have to get the rad rodded at a radiator shop or replace it. Dave W