These things are a beeatch to remove.

I cannot imagine the manual would imply that compression or anything else would counteract this sort of torque.

Is the pan off? You can sometimes position a piece of wood between the crank and the block.

Assuming you can get the engine to stay still;

The best way to generate the torque required is to position the breaker bar handle such that you can lift it off the floor with the saddle of a hydaulic floor jack. Unstoppable, safe, and requires less clearance than various 'lever arm extensions'.

Best of luck.

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1986 300E 5-Speed 240k mi.