Misadventure in toilet repair

or how to fix a toilet the hard way.

Plumbing DIY always seems to be harder and take longer then planned.  My toilet would refill every 5 minutes all day and night. There was a leak from the tank into the bowl but I did not know where. 

I replaced the valve assembly inside the tank which took me 3 hours.  The bolts holding the tank to the bowl were rusted.  I had to cut them with a hack saw.  Install a new assembly and turn the water back on.  Still the toilet refill every 5 minutes.

I finally found the solution.  The water refill inside the tank has a small hose going into the value assembly.  This is to refill the bowl while the tank fills.  The water was siphoning into the bowl from the tank. The solution was even simplier - cut a hole in the bottom of the hose to let in some air.  This breaks the siphon.

Sometimes the problem and solution is else where.  Best to keep looking.