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 ??
Pressure testing the cooling system is cheaper than scoping, and will likely point to a leak or not. I'm thinking perhaps some coolant got into one or more spark plug/coils; check under the engine cover.
Like mentioned above do a coolant pressure test. If the light is flashing you are maving catalyst damaging misfires meaning don't drive the vehicle or you will destroy the cat. If you can get the faults this will also help in finding out if the vehicle is having one cylinder issue or multiple. I have seen that when a vehicle over heats a coil will fail from the heat and causes misfires.
