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Discussion Starter · #1 ·
Lucky me the other three knurled studs were already removed and getting out the replacement, rusty bolts was easy. Not so much on this OEM guy.

I have had no luck with my bits at home nor the two Dewalt cobalt ones from Lowe’s I got tonight. I can’t get the bit to bore into the metal at all it just spins like a q-tip.

I know my neighbor uses an air chisel at his shop to pop these out but I don’t have that and was hoping a drill would work.

Any other suggestions? Heat hammering and drilling haven’t worked yet. Worst case I’ll have him pop them out but would love the satisfaction of destroying this thing that’s been fighting me three days now.
1033578
1033579
 

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Get a torch. Heat the surrounding metal up until red hot- hit with air hammer ( pointy bit ). Your only wanting to hit the stud…but watch out that hot little stud will fly right into your belly pan or onto a flammable hose. I usually block it from flying too far with an old metal license plate.
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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Cobalt is merely alloyed with a High Speed Steel for temperature resistance. For harder you need tungsten carbide. As drill bits get harder they also get mor brittle and must be held very steadily.
 
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Get a torch. Heat the surrounding metal up until red hot- hit with air hammer ( pointy bit ). Your only wanting to hit the stud…but watch out that hot little stud will fly right into your belly pan or onto a flammable hose. I usually block it from flying too far with an old metal license plate.
Heat is your friend.
When my studs started rusting out I wasn't in the mood to deal with it so I took it to a BMW specialist. He's done this job more than a few times and this is how he described it to me. Only other thing to be aware of is don't hammer too hard on it, the vibrations can damage the O2 sensors. Better to use a regular hammer and a drift than an air hammer.
 

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Discussion Starter · #5 ·
Thx guys...that bolt wins....for now
 

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The problem may be that you most likely work hardened the studs with the cobalt drill. This typically happens when the drill just spins on the material without cutting just like you described. You now need to use a drill that is harder than the work hardened material.

My suggestion: Try using a carbide drill (like Doug mentioned) with some tapmatic gold cutting fluid... Good Luck
 

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Lost but making good time
'11 335xi; '03 330Ci
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Use a flame wrench, hammer, and punch, as suggested. You are past the point where drills will do anything but try your patience.
 
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