Well, that ain't gonna work.

The loop plugs, which were original to that year, are wired in series using special resistance wires between the plugs. As installed, you have no connection to ground, so the plugs won't glow. The easiest solution for you is to find some pencil style glow plugs that will fit. There have been periods in the last year or so when availability wasn't very good, but I think you can find the Bosch plugs at several vendors now. Unless you completely revert to the series wiring system, which is inferior, you have no choice but to locate some new pencil style plugs.

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'79 240D