HELP ! drilling out broken tap in lower gearcase

[sirius3k]

I broke a Tap in my gearcase at the Water pump screw holes I was trying to clean out the holes<br />because of corrosion. Help..... the tap is a 1/4-20 I broke off about 1/4 ins of it....<br />the gearcase is aluminum it's a Johnson 1979 70HP....<br /><br />TNX

 

[hondon]

Re: HELP ! drilling out broken tap in lower gearcase

Trying to drill out that tap will cause more harm than good.It is much harder than any bit you can get at the local hardware store and is surrounded by soft alluminum.Tap removal tools are out there or you might consider a trip to the machine shop.

 

[Boatist]

Re: HELP ! drilling out broken tap in lower gearcase

Sirius3k<br />You have a big problem. I know because I had same problem. I had a bolt break off do to saltwater corrosion so I drilled it out them cleaned threads with a tap and of course it got stuck and I broke it off. I tried everything for weeks to get it out. Tried two different tap removal tool with out any good luck. Finally I got a dremel tool and got the small diamond grinding set about $9 from post tools and started grinding off the flutes of the tap. Took all day but I got it out with out any damage to to alminum. Mine was also 1/4 by 28. Got a bottom tap to finish clean out and all if fine now. Do not think you can get it out in a couple hours this way.