Right cure the problem so that you can build pressure in your system (ie sort any actual breaks in the water system, be it with a 2nd hand expansion tank w/e then chuck some K Seal thru the water system. Fingers cross you wont lose any coolant. I was losing coolant very badly after a new thermostat on my 850 put extra pressure on the waterpump seal. K Seal and 25 - 50 miles later and its sealed it. Amazing stuff. Apparently even been known to cure mild head gaskets :) Good luck Justin