1991 300E, I have developed a coolant leak. It is dripping on the passenger side, down the block, just above the drain for the block. I cannot see exactly where it is coming from, because of the exhaust manifold. I dredd that it may be the head gasket leaking, although there is no coolant in the oil, nor does the car idle rough. Can anyone shed some insight on this. Is it possible that there is a fitting/freezeout plug that I'm not seeing??????? Thanks to all in advance.