I have a 1990 325i sedan I swapped a s52 in. Coolant temp starts creeping up to about 214°F on my electric gauge. I am running a stock radiator, fan clutch, and small pusher fan up front. Cooling system was vacuum filled and there are no signs of leaks. Is this more likely an air flow issue or head gasket problem? No smoke out of exhaust or bubbling from expansion tank