Glow plugs -whats normal?

[stuart.mac]

Hello,

Nice simple question! The glow plug light on my car (307 HDi) flashes momentarily when I turn on the ignition, always less than a second. Should I expect the plugs to stay on for longer now its getting cold outside? I went to start it a while ago and the temp reading was 0, was a bit sluggish starting (dont think the battery will last many cold nights) and even though I ran the heaters a couple times it didnt stay on any longer than it did in the middle of the summer.

So, whats normal, should I expect to see them stay on for longer, or is that just how they all behave?

Cheers

[stuart.mac]

I should do more reading before i post on here - haynes manual states preheating period of 0.5 sec at 0 degrees C, so that sounds about right (for 2 litre HDi)!

[jmkent]

In essence, they don't really come on until -5degC or below