I wouldn't recommend anything but using the crank. Using the PS nut may work but there's a chance you could overtighten it and it does put undue stress on the PS belt. You can rotate the crank from below without removing the fan and it's much more controlled than using the starter.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL