Hole Between Timing Case and Block - Missing Front Block Plug After Machine Work

After rebuilding a 7MGTE engine that included having the block dipped/cleaned at a machine shop, there was a visible hole or gap between the front timing case and the engine block, despite having installed timing cover gaskets.

The freeze/expansion plug at the front of the block was removed during the machine shop's cleaning/dipping process and was never reinstalled before reassembly. This left an open hole between the timing case area and the block.

Moderate confidence — Original poster confirmed this resolved the issue