I'm pretty sure the bolts with 10.9 on them are grade 8...imperial vs metric i believe.

 

Correct, or similiar anyway. Grade 5 is 8.8

 

I've always soaked them real good the night before, and started the truck and let warm up and remove thebolts while warm. Never had a single iline break doing this.

 

I hate drilling out broken bolts, especially when at the #7 or 8 cylinders. I always presoak with Kroil as well. All of my vehicles use the GM Supercharged Grand Prix header studs because I get a huge discount from the local GM dealer.

 

used kroil.....that's all we used in the NAVY...still broke. One snapped right after we out the slightest bit of torque on it.

 

Lay off the protein powder hercules

 

i had the same thing happen 2 weeks ago. kroil then a snapped bolt....lucky for me mine was at the front of the head, and when the head broke off, i cracked the head of the engine temp sensor off with it. pissed me off! luckily it broke just below the head giving me room to back it out with channel locs.

 

all those nights beating off while deployed...I am a regular popeye!

 

How rusty are the manifolds?

PB or kroil, then use very gentle initial pressure.

If you shear the head off leaving shaft accessible, access to the head for penetrating oil is even better to help with the vice grips. Or potentially the double nut method depending on how much is exposed.

Disconnect factory Y first as well to reduce as many residual forces on the manifolds as possible.

If you shear off flush with head, either drill it out or weld threads on. One other idea (not tested by me, never had to) might be to cut a groove with a fine cutting wheel (dremel) in the exposed end for a slotted screw driver bit.

 

His truck is an 06 with 80K on it, clean clean motor no rust or hardly any grease. If one breaks I hope it is in the middle haha. I'll check out that kroil and didn't realize you guys were letting them soak for a week. Nice! I also thought that heating them up would make them weaker, but I guess it makes sense allowing the bolt to be hotter/more flexible