if it had water in the cylinder, you REALLY need to check it over well. VERY well. Put each piston at TDC, meaning turn the engine by hand until one piston won't go up any further. Measure (however you want to) how far it's out of the cylinder. Usually you can judge it by the "finger method", just by feeling it. Do the same thing for the other two cylinders. If you find one is further down into the cylinder at TDC, that rod is bent and will require replacement.
Didn't read the post very well, but was the pushrod bent? Was the adjuster screw loose? If no to both, you really should pull the valves out of the head and inspected them VERY well for bending, and for binding in their guides. Valves don't get "that" loose on their own, certainly not loose enough for a lash cap or pushrod to fall off.