Unfortunately I have little experience with freezing parts to remove them. However, I have noticed with stuck Bolts and so on that heating them beyond a heat they would normally be subjected to even if you let everything cool back to room temp seems to have a good chance to loosen them. Whatever expansion and contraction goes (movement) seems to help.

With the pre-chambers in a Cylinder Head it would be tough to heat them beyond a heat that is normal for them but I think you could dump some Dry Ice inside the pre-chamber or use that freezing spray.

One would think that shrinking the O.D. away from the carbon build up between the head and outside walls of the pre-chamber by freezing it would loosen it some even if you let it warm back up.

Please comment.

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84 300D, 82 Volvo 244Gl Diesel