Flush or Recessed Broken Bolt in Aluminum Removal

[Cardinal Grammeter]

The way I've done this in the past in cast iron, but not as effective in alum due its high thermal coefficient of expansion:

 

• Drill through bolt using LH twist drill
• Using largest feasible oxy-acetylene, tip, heat the stud quickly before aluminum expands.  This will yield bolt in compression so when it cools, it will be smaller.
• Unscrew bolt with easy out or larger LH twist drill

 

Has anyone tried these methods which are all over the internet?

 

• Hot alum (potassium or ammonium aluminum sulfate?) dissolves steel w/o harming aluminum.  NOTE:  Saw a tube using the McCormick spice effectively.
• Building up with weld.  Supposedly weld only fuses to the steel.  Build up until can grab with vise grips.  NOTE:  I've also read that you can lay a nut on the alum and fill with weld in one step.
• Burn oxidation away with car battery.  Build up with weld and then with good "arc-welding" jumper cables, run big current through bolt touching built up weld and aluminum near bolt.
• Slot bolt with auto body saw or Dremel cutoff wheel or similar, heat aluminum and unscrew bolt. (this would deface the aluminum with a slot.
• Or any other methods????

[Dawa]

yeah when I broke a stud in my aluminum had I just did the easy out method.

[john510]

I've had the best luck with a left hand drill bit.It usually spins itself out before even using an easy out.After breaking an easy out off in a broken stud i'm afraid to use them unless i have to.

[Cardinal Grammeter]

ADDITIONAL INFO:  This is the ground boss on the head by the fuel pump for the negative battery cable.  And it was broken 10 to 20 years ago I'd have to guess.  So the corrosion has been going on for a very long time.

 

I'm tempted to do the alum since I could easily clamp a hose on the boss to join and seal a makeshift reservoir for soaking.  Fill it up and forget about it for a few days.  And I could speed the process up by drilling through the "stud" too - that would expose clean metal which is more reactive.

[nl320what]

Once you drill it out, it should relieve the pressure of the bolt threads and back itself out or easily with an EZ.

[Crashtd420]

I have used easy out with both success and failure.... If you have the access which with the bolt your trying to get out you do.... i like welding the nut on because the weld heats the broken bolt too.... 

[datzenmike]

Use heat. Aluminum expands twice as much as steel. Maybe drain the coolant and heat around the bolt. The hole will become larger. You may have to heat and cool several times to loosen the grip between these two dissimilar metals. Did this for a thermostat cover bolt.

[Stoffregen Motorsports]

I always start with mechanical methods, first by trying to rotate it with a punch or a pick. If it rotates at all, I know an EZ out will get it. I try to drill to as large a diameter as possible, but not at first. If the EZ out doesn't get it the first time, then I move on to heat, WD40, and give it a try hot. If it doesn't move hot, then I let it cool and come back and give it another try. Usually the wait does the trick, but if not, that's when I go to larger drill bits and larger EZ out bits (small EZ out bits break easily).

 

Sometimes peening the broken bolt or even the area around it will help loosen the threads. Sometimes more heat. Welding directly onto the broken shaft of the fastener does help a ton, but it can be messy.

 

I know machine shops use the chemical method, but it has to be on a plane where the chemical can't drip out. ie- the threaded hole vertical. If it does drip out onto other components, that could be bad.

 

Only once in my life have I been unsuccessful at removing a broken bolt. It just happened to be a head bolt on an L motor. I had to drill it out oversize and use a threaded insert (no, not a heli-coil) for the repair. That was over 20 years ago.

[distributorguy]

I MIG weld to the top of the broken bolt.  Its adds heat, then quench with penetrating oil like Kroil.  If its 1/4" or larger, you can weld a nut to the bolt and just unscrew it after the heat sets in.  Otherwise apply enough weld so that you can grab it with a pliers and start unscrewing.  Again the heat from welding, or more heat added with a torch will typically expand the aluminum like Mike mentioned.  Some times it helps to screw it in a bit before removing it to break the bond.  Since you really can't weld steel to aluminum, it works pretty slick even on tiny screws.  

[Cardinal Grammeter]

Just swapped out my CO2 MIG bottle so I'm thinking about the MIG thing.

 

Still have to see buddy with Snap On Inductive Heater Tool.  Since the boss is a protruding cylinder longer than the bolt, there should be an inductive coil that should work perfectly.  For example:

 

Inductive Loops

Bolt Buster

 

Boss is right by the fuel pump.  Don't like the idea of welding 1in away from he FP.  There don't appear to be any fuel leaks or odor so is probably OK, but still...

 

NOTE:  The FP bolt that has the Neg Battery Cable was not tight at all.  It was when I installed but I'm guessing all the engine vibration loosened it.  (I've had many 4-cyl cars and none of them vibrate like mine.  If I ever put a clutch in it, the flywheel, pressure plate, and clutch disc will be individually balanced.)

Edited July 11, 2018 by Cardinal Grammeter

[datzenmike]

Maybe grind down the boss so the bolt protrudes more?

[rinigado]

stack some small spot welds w mig (or tig) until it's tall enough to weld a nut on. Then hit w penetrating oil. The heat shocks things loose. I wiggle it back and forth when I feel resistance once I get the nut on and start turning it out w a wrench, rather than try to keep turning in one direction; let's the oil work in a little bit I think. if it's flush, then just stack the nut on and weld in the middle.

[distributorguy]

DO NOT use an inductive heater on aluminum unless you want to watch it melt away.  You only need about 5-600 degrees.  Use a Map gas torch or the MIG method.  

[Cardinal Grammeter]

I'm going to try MIG today hopefully - depends how long I last in the heat roofing my house...

 

FYI:  My buddy blew up his Mini Ductor - one of the coil's insulation was damaged and it was shorting out, so it died.  Also, the inductive heater only works on magnetic steels - just like inductive cook tops.