[redmodelt]

You don't need to use fully boiling water. You can tell the difference between leaks coming out of the float and bubbles forming on the outside of it. The bubbles on the outside come off one at a time, the leaks from the inside are a continuous stream. I have checked several brass floats using the boiling water method. Even with bubbles on the outside and the water about to boil, it was easy to find the leaks. If you want to be sure, just tap the float on the side of the pan while still submerged to dislodge bubbles on the outside.