BMW Repair: 97 M3 overheating, head gasket failure, coolant loss

Question
Car has approx 122,000 miles, the thermostat and water pump were just changed. the radiator was replaced about 2 years ago. no signs of coolant loss. compression test was done and within spec. what could be ther overheating problem? it does take a while for the heat inside the car to come up.

Answer
Check operation of Auxiliary fan in front of radiator, Check Mechanical fan clutch. What do you mean by compression test. Cooling system pressure test? Radiator Cap holds pressure? Try a cylinder leak down test and look for bubbles in the expansion tank. Check for head gasket failure.
-Evan