Impact wrench or breaker bar for head bolt removal?

[Artfuldodger]

Yep….I learnt that lesson with manifold bolts.

I took the exhaust manifold off today and heated the stud nuts. I almost messed up, they were 12mm but somehow I grabbed a 13mm socket. Naturally the two that I rounded a bit were bottom ones. Luckily I didn't round them bad enough that the 12mm didn't fit and spin them off.
I actually heated them up and sprayed them with penetrating oil while hot.

 

[WishboneW]

X2 on Kroil. Best oil out there. Stuck rusted bolts, nuts, and everything. Use it on drill bits while in use as well

 

[zedex]

When I remove cylinder heads for reusing, I always use my impact. Never had an issue. Just start with the center bolts and work by way to ends using the cross bolt pattern.

And, when the head is off, I send it to the machine shop for a complete rebuild before installing it. No point going through all the time and effort to risk complications. Do it right first time and no worries

 

[fireman32]

Another vote for Kroil.
I’ve used impacts on head bolts, if the first try doesn’t turn it then it’s time for a bigger impact. Heating the bolt up helps.