ummm...are you sure it is coolant. Have you verified that your coolant level is dropping. One of the by-products of combustion in an engine is water, thats why when a lot of cars start up you will see water dropplets come spitting out of the tail pipe/s. The exahust system hasn't heated up enough to evaporate the water. If you are sure it's coolant then I would have to say you have a huge problem if your sure it's not the headgasket. MIght wanna tear that motor down again.