Oh Crap, I Broke a Stud Off

[popsthebuilder]

73 c20 350 th350
  Changed water pump, radiator. Went to change thermostat. Got right side bolt out with some effort. Tried to take alternator bracket/ thermostat hold down nut off of left side stud and snap!!! Left it alone put bolt back in right side. What is the most simple/ reliable method of extraction? If I have to drill and tap should I be worried about the depth that I drill? As always thanks in advance for any input.

[zieg85]

No worries on the depth of the hole unless you drill through the bottom of the intake.  The threads go into the water jacket. 

[pholliday1]

If a "little" of the stud is left and you have a mig you can weld a nut on top of it.

[popsthebuilder]

the water jacket explains the corrosion. Broke off flush, if not recessed.

[bd]

The Alden 1/4" - 1/2" Driil-Out set available from many hardware stores for ~$35 and a good penetrating oil like PB Blaster, or CRC Freeze-It might just be what the doctor ordered, if you don't have another solution already.

[Blazin]

Broke off flush with the intake? Or the top of the thermostat housing?
If its flush with the thermostat housing tke it off. You will have a 1/4, to 5/16 sticking out. Heat the intake around the bolt, and use vise grips, or a spiral / twist socket, or weld a nut to it to remove it.

[ehjorten]

I have never had much luck with screw extractors.  Best luck I have had is with LH drill-bits.

The most important things to remember when extracting a broken bolt are: 1) soak with a good penetrating oil.  Let it sit for a long time.  If you can spray it and let it sit for an hour or so, great! 2) when you start drilling out the bolt make sure you are dead-center.  Find the center and center-punch it.  If you drill carefully you can step-up the drill sizes until you are nearly at the minor diameter of the bolt.  At that point you can usually pull what is left of the threads out in a nice spiral of material.

If you can get the other bolt out, use that hole as a gauge for how deep to drill.  Sometimes with the LH drill bits the broken screw will actually back-out as you are drilling, but I fear in your case with the steel bolt in aluminum that there is probably some corrosion and it probably doesn't want to come out too easily.  In these cases it sometimes helps to heat up the area with a propane torch and then touch it off with a candle.  The wax will get drawn in and help lubricate the threads.

[pholliday1]

How about more on this candle trick first I've heard of that, Hows that work?