Welcome to GMT Nation...
No. It is NOT a just problem relegated strictly to GM Vehicles. But it is NOT necessary to remove the Engine Head to De-Carbonize the Piston Heads, Top Two Impacted (stuck within the Grooves) Compression Rings and Upper Internal Cylinder Valve Seats. Check with
@gmcman for his
Epic 'Thread' (
pun intended) when using
Berryman B-12 Solvent and
ACDelco Top Engine Cleaner to accomplish this task. Fortunately...because these Liquid Solvents can be directly introduced into all of the Cylinders via the vacant Vertical Spark Plug Holes in the Inline 6 LL8 Engines... the Solvents will get equally distributed to perform their proper Carbon Busting effects.
Regarding the other problem of experiencing Easily Broken TTY Bolts. This issue has to do with the universality of the Principles that govern How TTY Bolts "Stretch and Hold". In a Nut Shell... its a Toss Up between Elasticity versus the Ultimate Plasticity of the metal materials that will rebound only up to a certain amount of stretch and then...
PASS THE FINAL POINT OF METALLIC PLASTICITY AND FRACTURE.
Once these TTY Bolts reach that Final Stretch Point... there is NO GOING BACK. The next event WILL cause the Bolts to FAIL on an Atomic Level of Plasticity. When you try to 'unwind' these Bolts...the Metal will become so badly crystallized that the Bolts suddenly Snap-Fail completely... in Reverse.
Unfortunately... "The Broken Head Bolt Debacle" and I ...are "Old Friends" and I can tell you from intimate personal experience that the
"Hammer ...Then Turn Method" is a means to provide Hope to any Mechanic... only to Dash that Dream as soon as any One of those M11 X 2.00MM Head Bolts Snaps Clean Off. The only way to compound this problem is to imagine (as I once did...) that it is possible to Drill out the Broken Head Bolt remnant and use a Reverse Twist Drill Bit to eat into them backwards and unwind them... WHILE THE ENGINE HEAD IS STILL SITTING ON THE ENGINE BLOCK. It's Not.
Nope... BAD IDEA.
This problem is something akin to having your favorite Girlfriend telling you,
"Honey... But I'm only a LITTLE BIT Pregnant..." ;>(U)
The ONLY way to get through this Nightmare ...is to continue removing ALL of the Head Bolts. Some will come out with loud "CREAKING" sounds... but more than likely... More than Half of them WILL JUST SNAP RTF OFF.
So... Just roll with it... and WAIT UNTIL THE ENGINE HEAD IS COMPLETELY REMOVED before attempting to counter-drill and extract the remaining Head Bolt Remnants. Just be aware that you should expect an
ENORMOUS Release of Kinetic Energy as each and every Bolt that Snaps Clean Off essentially does THIS:
Do NOT attempt to re-use ANY of the Old Head Bolts that Do NOT Snap Off. Purchase the UPDATED version as per
@m.mcmillen 's experience with using the UPDATED flavor from Fel-Pro ... as their Bolt Stretch Parting Lines have been elevated to a higher position along the Bolt Shanks to reduce the chance of them Snapping Off during future R&R efforts.
Here are some images I took of what happens ...More Often Than NOT... when trying to Unbolt the GM Atlas LL8 4.2L Engine Head Bolts for both the 2002 AND the 2004 GM 4.2L Engine Heads: