64 273 new rebuild now with coolant in #6 (It's a Hybrid!)

67Dart273 said

First thing I'd do is clean up the head and deck and get/ borrow a precision straightedge and check for warp.

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EDIT
Bear in mind it could be a crack in cylinder. Examine it closely. And could be crack in head such as intake port, etc Pull the valves out of that cylinder and examine interior of seat/ port area


LOLOL. One thing you could do is swap heads to other side and see if the leak follows!!!