I have a new lhe. (the afco ultra pro series dual pass) After running the car the coolant tank leaks down. It has done this a couple of times and I will refill with tap water. I have already used some water wetter with first fill up. I have the new ultra pro series he. I do not have any leaks that I can visualize. Any ideas how to make sure all the air is out of the system or if i have another problem that I could check? Thanks