I thought you could put the piston at TDC and avoid pressurizing the cylinder. The valve can’t fall in with the piston at TDC.

Too bad you can't use the old dowel in the spark plug hole like on a gasser.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine