i fitted another engine in my s2 rs turbo asoon as i drove it up the road it over heated i run a compresion test and found that cylinders 1 and 4 were low,so i replaced the gasket and also the head coz i had a spare head at home that was off a old engine of mine coz i know it was good.but it is still overheating i have removed the thermostat.the fan runs constant,the rad seams to be flowing ok.am running out of idears.