Mike,

Does my drawing below depict what's happened to your cyl. head?

I took your drawing, flipped it so the glow plug is in the same orientation as the cutaway drawing with both on the computer screen, taped a piece of clear cellophane on top of your drawing and drew on it with colored markers.

Orange is the space you have drilled
Green is coolant passages
Purple is pre chamber and injector
Yellow circles are coolant passage areas that have been breached.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked