Removing sheared bolt - VP 2040 Raw Water pump

jac

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Having replaced the impellor whilst ashore I checked the pump when afloat last weekend and spotted a drip. Tightened up the face plate only to have one of the bolts shear off. ( on the positive side - the drip has stopped!

This has caused me 2 challenges.

1) Is this likely to be symptomatic of the other bolts on the face plate ( didn't use that much force - simple hand screwdriver - one hand, no assistance) and should they all be replaced. ( gut feeling is yes)

2) How the hell do I get the old one out. I may be able to get hold of it when the plate is off and twist but don't really want to have to drill out and tap - anyone got any brilliant ideas.

To be honest - i'm very tempted to leave it for the time being. It works, plenty of other bolts holding, it doesn't leak and worst case - the pontoon we're on I could sail onto if required
 
Once the front plate is off the pressure on the remaining part should be reduced...
I would expect it to just wind out with a pair of pincers...

Those screw extractors look rather too big for any hole you'd be able to drill in the remaining part.. But they shouldn't be necessary.
 
These tiny bolts are usually brass and are susceptible to dezincification, hence shearing under light torques. If you have been experiencing leaks it could be that others are in the same condition. I suspect that you will find the broken one easy to remove without the cover in place.
 
When you have removed it, suggest you replace the cover with a Speedseal which apart from being much easier to remove and particularly replace has stainless thumb screws. So no more messing about with those fiddly little screws and losing one of them in the bilge!

Edit: beaten by a minute.
 
The Speed Seal uses only four of the existing threaded holes, so one screw missing shouldn't matter in the short term.
 
I contacted speedseal who don't make a cover for my pump. I asked about just replacing the screws with more convenient thumbscrews and was advised that they would not compress the paper gasket enough.
 
Once you remove the cover the projecting length of the bolt might be like a short stud so use a stud remover.

Fortunately your stud appears to have sheared under tension but if had sheared due to corrosion or because the bolt had grounded at the bottom of the thread it might be more difficult to remove.
 
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