Snapped Bolt ... FIXED !!!

stripminer

stripminer

Junior Member
OK,, in my efforts to be a better boat owner ( brought about by the fine folks here at V20.com ) I decided to change out my thermostats on my 1988 Yamaha 130 for the first time in 8 years.

Well,,,, as you can guess 7 of the 8 bolts came loose but good old number 8 snapped right off.  I am guessing that I need to drill out the old bolt and re-tap it. My question is,, do I need a larger diamter hole and then a larger diamter bolt ? When I tap the new hole will I have threads along its entire length ? ( the old bolt only has threads at the end )

Anyone with experience who is willing to give me an idea is greatly appreciated.

                    Thanks,
                          Tom
 
Re: Snapped Bolt

Sometimes if your lucky you can use a smaller drill bit than the bolt, take a punch and make a good deep mark in the center of your broken bolt. Then drill a small hole in it, take a screw driver head like a phillips and punch it into the hole to give you something to grab. Sometimes you can take the punch and move the bolt around in a circle to get it out. Keep spraying CRC 6-56 oil on it. Stay cool man its coming out, just a matter of time.
 
Re: Snapped Bolt

The trick here is to drill the old bolt out. Nw I say trick because you need to try to drill stright down the middle!!
Try to put a punch on the center of the bolt and then start drilling slow.
You want to drill like 2 sizes smaller then the bolt. Then you can use a easy out to get the rest. You maybe can try to go one size smaller then the bolt but then you are getting close to the threads!
After you get it out you will need to re tap the threads to get them clean.

Like stripminer says Slow and steady, and oil the crap out of it!! She will come!

Good luck!
 
Re: Snapped Bolt

MJ is right, the trick is to drill it out straight. If it wont come out with and easy out you can buy h helicoil kit. You'll have to drill the hole out a little oversize. The supply a bottoming tap in the kit. That a tap that will put threads allmost the whole way down. After you tap it, you install a threaded insert into the hole to bring it back down to the original size. If you get a block of hardwood and drill a hole in it, you can use it as a drill guide buy sliding the bit thru the hole you drilled. Hope it helps you
 
A good trick!

I read somewhere that if enough of the bolt is still exposed, you can cut a groove across the top so that you can use a flat head screwdriver to back it out like a regular screw. Use a dremel with a cutoff wheel to cut the groove. It might be worth a try before you try drilling.
 
Re: Snapped Bolt

All these are correct, if you do have a little left try the slotting thing and put a little heat around the screw and then then try it. I would try to avoid drilling out for a larger fastener unless you have to, I would rather Heli-coil it (nothing wrong with a Heli-coil in my book). Let us know what size bolt it is and we can let you know the tap drill size, this would be the largest hole you would want to drill it out with.

Good luck,
Scott
 
Thanks for all the support and advice. I ended up drilling out the bolt best I could. I then bored it out to 17/64 and tapped it at 5/16. I ran a new 5/16 stainless bolt on a lock washer with a new housing cover ( cracked it during work ). Started her up and no leaks. I'm gonna run this 1988 for another 10 years if I can !!

Tight Lines,

- Tom
 
take the bolts out now and put on some neverseize and you wont have that problem again
but why did you wait so long to change them in the first place, i change mine every year,. but then again i boat in salt water and have a 150 mercury outboard
 
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