Very seldom does it work that easy, because the pressure from the hull being submerged will cause more leaks than the static pressure of water just being there.

If that works, great, if not, take it to the pond.

I had a livewell fitting break on an ol champion. I removed the drain plug, used the livewell shutoff valves to close off the livewell drains. Filled up the livewells and found the front livewell fitting was broken. Hope this helps...........all in the driveway, if that does not turn up the leak do like pat said and take it to the lake