Since things expand with heat and contract with cold, I wonder if it would help to hit it with that spray Ice stuff while the manifold is hot? Then again, if that stuff really works I suppose you might crack the manifold.

 

Heat is what does it. Generally, get the system up to full operating temperature (a half hour run, at least) and then get on it as soon as you can, and it will come out without much difficulty.

 

I did a little google. I guess they just use (an expanding gas) like butane to apply cold. Those small cans of butane for refilling lighters have like a nipple when depressed the butane comes out, expands and of course sucks up heat. Anything a guy pressed one of those on would get cold pretty fast.

In very different situations, I've seen a huge difference with heat/cold. Put your bearing in the freezer, then heat where it goes, the "socket, and you might almost push it in by hand. Steel wagon wheels, you heat on a fire, then slip down on your wooden wheel, quench it with cold water it shrinks tight, and off you go! (need horses of course...James Watt first described horsepower. Horse does 550 ft-lbs/sec. He figured that because he was selling steam engines to people using horses for power. Gotta know which engine to replace, say 6 horses.

 

In addition to having the slot that can allow it to expand, those things also put your torque in the wrong place. The six-sided edge on the O2 sensor is pretty narrow, so there's not a lot of gripping surface. When you put that stupid O2 sensor socket on it, the ratchet handle is then far enough away from it that it can put a twisting force on the surface rather than a straight grip. It's a perfect recipe for a rounded sensor.

I always just use a big 7/8" open ended wrench so that the torque is perfectly parallel to the surface. I have never rounded one that way. If I did start to round the edges on one, however, I have one of these that I would probably use next:



Once that bastard locks on tight, it's on.

 

Freedgrs (originally), tip, cut the wires and put a 7/8 box wrench on it. Like Shakey points out, the torque is then on a plane with the "nut", and there is no gap to expand. A much better "purchase" on the thing. A long expandable socket and a goofy angle.....well you see how that works.

On mine, with the frame jacked up and the front axle hanging, and going at it from the front was the ticket. Removing the wheel doesn't hurt.

I often put blocks on my ramps for support, and use a jack. I don't use Jack-stands as I don't have a level cement floor.

 

I'm with Flintstone.
Tapping the wrench with a hammer after heat & PB blaster.

 

Yea, that shock-wave while it's at all the torque you can get can un seize things. Often not so easy to do though.