i was taking of the turbo so i could get access to the front engine mount in order to weld a nut to one of the the broken bolts and remove it.
whilst taking off the turbo i realised the lower final stud closest to the thermostat was missing it had already been broken, can i extract this via welding a nut to it, will thre weld also stick to the alloy head, if i cant get it out is this stud going to cause a problem in performance.