My 1988 turbo 114k recently started having boiling coolant in the overflow tank when letting the car run for about 15 minutes. Temp gauge shows normal range. After letting the boiling settle down (apx 5-6 min), I use a turkey baster to return the coolant to the radiator. Thus returning the overflow tank level to "cold level." Next morning after 15 min run time it's the same thing. I have checked for coolant in the oil, white exhaust, no air bubbles in the radiator neck, and today I'm going to pickup a hydrocarbon testing kit. However, I don't believe the problem is a blown head gasket just yet. The car runs good and has not overheated after a 100 mile drive in 95+ temps. Any ideas?