There is a stainless steel bolt (about 3/16 diam) that
is threaded into the center of the motor shaft in an old
dishwasher that I am repairing. In order to remove the
impeller and other parts for replacement, it was necessary
to unscrew the bolt. Having no success, I ground the head
off, thinking I could then liberally apply penetrating oil and
eventually get the bolt out by turning it with a vice-grip.
Despite numerous oil applications and twisting to the
breaking point, the bolt has refused to unscrew.
It is very important that the bolt not break off, as it
would be very difficult for me to redrill the hole concentrically.
Would it be worth trying to heat the bolt with a propane
torch? How should this be done, and what would the risks
be? Would there be increased risk of shearing the bolt off
after heating (assuming it still won't yield at the threads)?
Your advice is appreciated. I will tell you that I do have
a backup plan to extend the bolt length with a collar, but
this is not optimal as it will require enlarging the center hole
on the impeller and other problems. (This of course assumes
the current bolt remains unbroken.)
Thanks very much. (Don't hesitate to recommend the
backup plan if you really feel that it's the best route.)
Frank