This is less of a "how do I" question and more of a general knowledge check.
Recently I've been having trouble with an overflowing toilet. Fortunately for me (in this situation), I'm a tenant and not a homeowner so maintenance is provided by the property managers. However, I'm about to be a homeowner in a few months and am simply trying to understand how the fix that was implemented (augering the toilet drain) solved the problem.
First, the problem
Simply put, the toilet overflows. I've not caught it in the act of overflowing, as it doesn't overflow immediately after flushing the toilet. Usually, we find water on the floor and sometimes dripping through the downstairs ceiling (if it's overflowed in the night). Water is found running out of the flush lever hole in a small stream and the water level in the tank is much higher than usual.
The "band-aid" fix
When this happens, my initial reaction is to turn off the water line to the tank and flush the toilet, which (of course) drains the tank and prevents it from refilling. Once the tank is emptied and the water is off, the toilet seems to stop overflowing.
The maintenance fix
After stopping the leak and setting out bowls to collect the ceiling drip, I called maintenance and told them what happened, and that I suspected the float (which is a "floating cup" type, per the internet) may have a leak that slowly allows it to sink and causes the fill valve to reopen. Their SOP is to leave a note whenever they come describing what was done, which in this case indicated that they found no problems with the toilet and that they "unclogged the drain".
The actual question
To my knowledge, the drain wasn't clogged - at least not in the usual way where the water in the bowl can't escape and flushing causes more water to enter the bowl. Can a drain clog cause the toilet tank to overfill? Am I just missing something obvious?
I was able to get some measurements, and it appears that the overflow tube is about 0.5" higher than the hole where the flush lever attaches to the flush arm. This would explain why the overflow tube doesn't work as intended.
My wife also reports that the toilet has not overflowed again since the maintenance person re-opened the shutoff, however she did close the shutoff again as a precaution.
Can that pipe be cut down to allow the overflow tube to work as intended? Then, at least, if maintenance won't believe me that there's a problem with the filler valve I won't have to worry about the toilet overrunning when we're not home.