My belated tuppence-worth on removing stubborn crankshaft pulley bolts (XUD engine). When I did the timing belt almost immediately after buying our Xantia (11 years and 67,000 miles on the original belt) the bolt wouldn't shift it:
Air gun screwed up to the maximum - "use the air gun - that'll undo anything." - didn't budge.
Two of us swinging on a 2-foot breaker bar with the car in 5th and the hand-brake on - eventually we defeated the hand-brake!
Out of gear, lower the lift so that we could prop an extension on an axle stand, support the end of the breaker-bar on a block of wood (rather than the concrete floor). Stand well clear, blip the starter (twice).
Loud CRACK! and the socket fell off. Oh, sh*t, the bolt's sheared! Relief all round when the bolt head was found to be still attached and the bolt turned fairly easily.
So Jim's method really does work, even when all else fails.
Crankshaft pulley bolt
Moderator: RichardW