If you only have a small drip coming from where a drain cock should be, you have a lot of crud in the water jacket. While I would like to recommend that you get all the crud out of your water jacket, it is much easier said than done. The only way that I have been able to accomplish total clean out was by removing all of the freeze plugs including the ones in the front and rear and flushing it out with a hot pressure washer blowing through every coolant hole in the block including the ones under the head. It was also necessary to stand the block on end and then on the side to get everything out.
