My '52 8N tractor was losing antifreeze by overheating, so I replaced the water pump thinking it was faulty. It continued to overheat. I checked the radiator fins to make sure they were clean. This spring I put in another gallon of 50/50 antifreeze. I used the tractor to mow the lawn for 3 hours and the radiator is empty all over again, can't see any fluid line there. The radiator cap has milky substance underneath, like ice cream. Do I have a cracked block where water is getting into the block and mixing with oil? I never abuse my tractor, and use it only for mowing and only three times to plow snow this past winter. Where is the water going? I can't see any leaks from the radiator at all. Thanks for answering this post.