The oppressive heat in recent days led to a crack in the radiator expansion tank on my 1995 E36 (101,000 miles). The coolant eventually drained which led to an over heating. The car was driven a short distance (by a young son) to safely exit a highway. The temp guage registered high but not to the max position (light on). The check engine light did appear. The car was towed to a garage where the expansion tank was replaced, coolant refilled and bled. The car idles perfectly without overheating. The car runs rough when the revs are increased. The check engin light then flickers. My fear is that it is an issue with the head gasket. The engine oil shows no sign of antifreeze/water. Does anyone have a prognosis before having the car towed to the dealer for a scope ??