So my buddy Barry was recently activated in the Army; he's been a drill sergeant on reserve status for several years. My wife is good friends with his, so they hang out a lot in his absence and I've taken over maintenance duties at their house. The girls requested that I fix the hot tub that Barry got too pissed at and has left sitting for about a year.
During it's period of inactivity, he didn't drain the pump and without heat, it froze up solid over the winter and cracked the impeller housing about 3/4 of the way around. I figure 'no problem'. After fixing a few other minor issues, I pulled the housing and impeller (which is also cracked). I ground the crack out with the Dremel, drilled the ends so it wouldn't spread and filled it all with epoxy. I'm telling you - it looked GOOD. I put it all back together the next day and started filling the tub. No leaks, all good. Start up the pump and heater as the tub gets half full, still good. The pump is working fine and water's circulating well, so the impeller is holding up just fine.
Then the jets kicked on and the pump motor hit second gear (who knew these things had 2 speeds?). The housing split all the way around from the pressure and got everything within a 12' radius soaking wet.
The pump housing is NLA, so it's still sitting there, waiting for me to find a good deal on a complete pump assembly.
Usually, if something isn't going to work, I have an inkling beforehand, but this caught me completely off-guard. That's probably why it pissed me off so much.