A previous owner of my truck installed some home-built steps which the welds were rotting away on, so I was removing them and the first body mount bolt literally snapped with little/no torque applied. Upon inspection, it would appear that it has been cracked right at the head of the bolt for some time. How can I remove this bolt now - the entire bolt is still in place, just no head. I tried cutting a slot in the exposed shank and working it with a large screw driver but have had no luck loosening it at all. Soaked it in PB blaster, applied heat and soaked it again, still no movement. Fortunately, I have not yet stripped the slot..... yet.

06 Cummins Mega Cab

front drivers side body bolt broke


Head and shank

Slot in shank of bolt remaining soaked in PB and heated several times...

 

Flip the bolt over so the penetrating oil can soak in better

No, just joking.

Can you weld a nut onto it?
Or maybe there is access from above so you can get some penetrating oil into there?

I don't see how much space there is, can you put on 2 nuts on top of each other so they lock against each other, then take the lower of the nuts to undo the bolt?

 

I was going to suggest welding a nut to it. That usually works fairly well.

 

Tap on it with a small hammer for a while (like a a hundred hits or more), I have had a lot of success getting rusty stuck fasteners out that way. Basically you are vibrating the rust away. You don't want to mushroom the end of the bolt it so go lightly... sometimes I use a brass drift. I think the tap method works better than just penetrating oil.

Welding the nut on works pretty good, but not everyone has a MIG machine sitting around.