|Here's what I've come up with. Broken
bolts are something we've all dealt with and including myself screwed up
more then can be fixed. A good friend of mine showed me how to extract
a broken bolt without screwing up the threads in the engine block, I just
want to share it and hopefully help someone. All it takes is a little time
This pic shows some of the tools for the job:
When a bolt is broken off, First thing is
to take the cover off, if the nub of the bolt is still protruding out and
theirs not enough to apply a wrench, Take a grinder and grind it down flush
with the engine block. Make sure not to grind into the machined surface
of the engine block.
Once you have it flusheplace the cover and
use only a couple bolts to hold it in place. Using a 1/4" center punch,
Incert the punch into the hole that has the broken bolt and tap the punch
until there's and indention in the center of the bolt.
Using a tool called a drill bushing, Its a
bushing with a 1/8 hole through the center to keep the drill bit in the
center of the bolt as your drilling through it. Its important to have a
sharp drill bit so to keep the bit from wondering to the threads.
Place the drill bushing in the hole and with
an 1/8" drill bit, start drilling. Do not apply alot of pressure as it
will cause the bit to wonder. Take your time, when the drill bit gets close
to the end of the bolt, it will in most cases start grabing more metal,
Because the the metal is getting thin at the end of the bolt and we don't
won't to break the bit off in the bolt.
After drilling through the bolt, remove the
drill bushing and cover. The hole in the center of the bolt will be the
guide for the next size drill bits, Which is a 9/64" The last bit to use
is a 5/32"before using an easy out, Fill the hole up with pentrating oil
or PB blaster and let sit over night. This will better the chances of getting
the bolt out.
Using a 1/8" easyout, Tap the easyout down
into the bolt until its tight. Take an ajustable wrench and screw it out.
Do not get aggressive With an easyout, It will break
The broken bolt is out. In some cases bolts
are hard to remove, even with penatrating oil and an easyout. In this case,
Go up to the drill bit size that will leave just enough of the bolt without
getting into the threads. Take a small chisel or punch, Start tapping on
the punch to knock the thin part of whats left of the bolt to the inside,
If the bolt has been dilled out thin enough it should come loose from the
threads with easy. After 3/8" of the bolt has been removed, Blow out the
chips in the hole with compressed air. Apply wd40 or cutting oil, Take
a 6mm tap and ease it down until it tightens up, Take the tap out and blow
it out again. Do this proceedure until all of the bolt has been extracted.