there is another product you can also try, it's Block seal, you do a flush of the system, then pinch off the lines to the heater core, run the engine up to over the normal operating temp, if having to blocking the air flow throught the rad for a few min till the leak stops. Then drain the cooling system and let sit for 12 hours, its suppose to even fix head gasket leaks, and another product is Iron tite.
