[insite]

@blue:

absolutely i've used EZ-Outs. they're great in some instances. unfortunately, i've had limited luck with them when the corrosion bond is this strong & the metal is so soft. the key to successful, painless extraction is a little recon & a lot of patience.

in my situation, i know i have two primary problems: a VERY strong corrosion bond and a VERY soft metal. if i choose to drill, i want to either leave the bolts as-is (soft!) or to anneal them further to simplify drilling. if, however, i feel confident i can break the corrosion bond & successfully apply torque, i want to HARDEN the bolts by heating & rapidly quenching. if i mis-plan, i may have to drill a hardened bolt. if i anneal & then try to use an easy-out, the metal may be too soft for a high-torque bite.....

analysis of THIS situation has shown me that i have to do both: eight of them will be hardened and the last two will be drilled out. first, i want to try to break the corrosion bond. heat will work, but the problem here is that the head is aluminum, which is a MASSIVE heatsink. it will be hard to get enough heat into the surrounding metal to really assist me, esp. considering my only torch at the house uses MAPP gas. the alternative is to cool the fastner with some dry ice. the rapid contraction is frequently enough to break or severely weaken the corrosion bond. it can even make some more 'room' for penetrating lubricant to get down in there.

once i've broken the corrosion bond, i will remove 8 of the fasteners by hardening the metal & twisting them out. i will do both at once: i will weld a nut to the protruding stud & quench the pair. after that, they should twist right out. the wire-feed welder will get the bolt MUCH hotter than my little MAP torch.

the remaining two are really already annealed & very soft. i will grind them flush with the head, center punch them, & drill w/ left-handed bits. it's possible an EZ-out will back them off. otherwise, i'll have to drill up to 7.5mm & then dig out the threads & chase with a tap. in the worst case, i'll drill oversize & helicoil.






@stroked:

never seen that before! makes a lot of sense, although i don't know if it will work as well as dry ice. i'd be willing to try it, but i can't seem to locate any that i don't have to special order......




@clickman & bud:

i have snapped of EZ-outs before. NOT GOOD! at that point, i'd just haul the block to a machine shop & let them deal with it. best to know when to cut your losses. the trick in that scenario is to vaporize the EZ-Out with a plasma cutter & then drill out the remainder. i have muppet fingers & would probably melt the head. that falls under the category of 'pay the guy'.




@pat:
anytime! i can't take credit for the REALLY good stuff; tholyoak has helped me tremendously with understanding the DME & various program parameters.....