Re: rocker adjustment
After doing what others have suggested, and fixing the hose leak, and IF no leaks are found but you're still not sure try this:
Fill the rad, run engine to warm it up enough to open the t-stat and top off the rad. Assuming the header tank is connected have some water in there also. Go drive it. Maybe even step on it if your want. Come back, let cool a bit, and check the rad and header tank. They should be exactly where they were when you started. To double check this let it sit overnight and top off the rad again if necessary. Now drive it again. You should see no changes it water level anywhere. If water is "lost" then it has a leak somewhere. You also may notice you've "gained" water in the header tank. Not good either. A truck that doesn't leak can drive "forever" without using water as long as the header tank is kept full. A "normal" truck will loose tiny amounts of water from the header tank but it will take weeks of driving to see much difference.
So, IOW, in the course of normal driving you're using water then there is something wrong somewhere.