Non-critical question:

Does glow plug power turn off when car starts?

IAW, if I restart car when still warm without letting it glow, is power automatically cut off on starting.

Just curious to see if I am saving battery by this practice.

1983 300CD (617 engine)

Glow cuts out when the key is released from the start position unless someone has done an afterglow mod.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

You might not be doing your battery any favors. The glow plugs draw maximum current during the first few seconds of operation. Your practice combines maximum GP draw with the added draw of starter operation. I suspect that a short pre-glow is a better alternative than skipping it altogether.

Theoretically, yes. I doubt it adds up to a material difference. Do you engage the park brake and turn off your headlights while waiting at a stoplight?

Sixto
87 300D

There is a White Wire coming up from your Starter Solenoid to the Terminal Block in front of your Battery.
Screwed into the same spot as the White Wire is a Purple (Lavender?) Wire that goes to your Glow Plug Relay.
This means all of the time your Starter is Cranking your Glow Plugs are on.

If you want to save your Battery disconnect and tape over (so there is not short circuit) the Purple Wire and your Glow Plugs will not go on during cranking.

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84 300D, 82 Volvo 244Gl Diesel

Doesn't disconnecting the purple wire power the glow plugs for the maximum duration?

Sixto
87 300D

Actually, that will prevent the cycle from terminating at the completion of engine start. The glow cycle will continue until the timer runs out.