Snapped Bolts On Pump...Safe to use still?

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NullQwerty

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Apr 23, 2008
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Hey folks,

While working on my pump, I began removing the bolts that attach the end of the pump (by the electronics) to the pump itself (I know...very dumb idea). I removed 2 bolts before realizing that I hadn't actually detached them and instead I had just snapped them. There's about 1/4" of thread left on each, but they don't go in anymore.

I'm wondering what people think I should do. Here's my options as far as I can tell:
a) Detach the other two (possibly snapping them in the process as well). Then disassemble the the pump. Try to tap out the snapped threads that are stuck in there and replace the bolts with new ones.
b) Bring the motor to a shop and try to have the end cap welded to the body to help support the absence of the 2 bolts.
c) Do nothing...the end seems very well attached despite only having 2 of the 4 bolts. Only problem with this is that I don't know if the bolts are doing anything else that I can't see. And also, I don't know what will happen once the pump turns on...is there a high degree of pressure on the end that can blow off the end without the 2 bolts?
d) Do nothing and replace the motor.

I'm leaning towards option 'c', but wanted to know if any experts thought it would be a bad idea for any reason.

Here's pics of the bolts:

Thanks!
(Note: I had this in an unrelated thread concerning a leak, but decided to start a new thread for this problem)
 

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Hi,

Those bolts don't connect to the pump. They hold the motor itself together. Only time you take them out is to disassemble the motor to work on it.

Two bolts will probably hold everything together. It is usually a tight fit even with the bolts out. Having said that, I don't know if I would run it that way myself. If you have a motor shop close by check with them or even give a call to AO Smith or whoever makes the motor for advice.

Hope that helps.
 
Thanks everyone!

I can't for the life of me figure out why those bolts are like 6" long to begin with, which is why I asked. If they truly are as they seem, just to hold that end cap on, then maybe I'll just have someone weld a seal around the seam to help hold that end cap on to the motor. Sound like a good idea? The warranty is already expired and probably void anyway, so I won't need to disassemble it in the future. I have a feeling taking off the other two and trying to tap out the stuck threads will prove difficult. Too bad I can't find a motor repair shop by me.

As a note...I'm not really worried about it breaking down the road as a result of this. Despite being only 3 years old and taking it inside over the winter, the motor is all corroded anyway. I was more worried about it flying off at 100 mph and possibly hurting someone. From what I can tell though, I don't think that would happen.

Thanks again!
 
Having those screws evenly torqued helps keep the shaft and bearings aligned - they can bind slightly if the end bells of the motor aren't held parallel and aligned. I wouldn't recommend welding, as the heat would tend to distort the end bell or the motor body, which could let the rotor scrub in the stator and/or bind the bearings, and the heat could break down the insulation on the windings which would be real bad in a hurry. Sorry that you can't find an electric motor shop in your area. Most metropolitan areas have access to one somewhere. If there's any industry around, motor work usually follows.

Technically, as you've surmised, the repair would be to disassemble the motor, remove the broken screw parts from the motor end bell, and get new screws to replace them. The motor isn't really that difficult to pull apart usually, if one is careful. If there is enough broken screw to grab with a pair of vice-grips, it should be easy to pull the remains, otherwise you'd need to drill/extract the broken parts. Some penetrating oil like PB Blaster or Kroil would help immensely. Running a tap into the holes to clean them out and/or a touch of some anti-seize compound at reassembly would be good too. Replacement screws can be made from a length of threaded rod and a nut. Yep, that's the preferred fix.

If your broken screws are not adjacent to one another, you could probably run for a long, long time with the two remaining screws opposite one another, but if they're adjacent, the end bells will tend to open up on the opposite side where the broken bolts are/were. The amount spread can vary from 'not really noticeable' to 'won't reliably run anymore'. If your motor runs like this, you could probably run it to failure. It really shouldn't really fly apart if it breaks - it should start to separate and make lots of sights and sounds, and trip the breaker.

If there's room, you may be able to get a bar-type clamp on the broken-bolt side and hold the end caps on with it, and just run it that way. Just don't tell anyone that I told you to do it, OK? Our little secret, right?
 
Thanks for the great response! Makes more sense now.

Ok...that changes my plans a bit then. Since starting the thread I found a motor repair shop! I think I'll bring it in. I can maybe do it myself, but he said it would be under $50 and I don't really know what to expect when i open that thing up and whether I'll be able to gain access to it like I need to.

If it turns out being more or there's any reason they won't do it, I'll try it myself or see about using a clamp as you suggested.

Thanks!
 
Since starting the thread I found a motor repair shop!
Click to expand...

Great. They should actually have replacement screws (in a box of motor screws stuffed under one of the workbenches, I'd bet) and they would have expertise with that repair.

While you're there, ask them what they would typically charge to rebuild it (brushes, bearings, etc.). Not that you want it rebuilt, necessarily, but if the time does come for it to die, you can compare it with a full replacement. Just good info to have.
 

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