, so glow plugs are arguably more important once started than they are in the starting process, particularly in current UK temps.
So do the glow plugs stay on once the engine is running? I thought they were purely there to get things warm and aid starting?
Shows what I know!
In the UK, a common rail diesel doesn't really need glow plugs at all, but does reduce cranking times in very cold temps (well, UK idea of very cold), and improves idle and emissions after its started.
Yes, glows stay on after cranking has finished. There tends to be 3 stages of glow plug control on modern diesels, pre cranking Iif required), cranking (if engine cold) and post cranking (usually a complex algorithm based on fuelling and temps).