[kickininthefrontseat]

does it matter

I often flick the engine straight on, will that damage anything

[rustynutz]

It supposedly shortens the life of the glow plugs....

[Dazzler]

I got 68,000kms without waiting for the glow plug light.. was still starting fine when I traded her...

Here's my take.

Compression alone is insufficient to ensure each charge gets hot enough to ignite so it is helped by a permanent hot spot, the glow plug. Once the engine is running the ignition itself maintains the glow and AFAIK no current is required and all is well. Before the engine starts however the glow plug is cold so to emulate the running plug temperature it is artificially heated with electricity for a few moments.

Waiting until it heats will make starting more reliable.  In practice it appears to work fine without waiting, at least in temperate climes.

[Phil №❶]

pip

do we know what makes the glow plug stop energizing, is it a timer or some other mechanism. If it's a timer then your theory of ignition & electrical heating together would probably shorten their lives.

dazzler

Was it your habit to wait for the light to go out.

[Dazzler]

dazzler

Was it your habit to wait for the light to go out.

No, quite the reverse.. The CRDi was only my 2nd Diesel ( I had a Ford Courier work vehicle for a short period)

I tried to remember to wait when we first got it but I mostly forgot and sometimes just in too much of a hurry. Pretty much started 1st time every time 

[Phil №❶]

Hmm, interesting, my daughter's car (Lila), has recently developed a miss at start up, only after resting overnight. Could we be looking at glow plug failure. These are our 1st diesels so I don't know much about them yet. 

And just to add... even if not waiting, the glow plug will still heat up. Just that it might not be at optimum temperature when you start the engine.

I didn't wait when I first got the car as I was unaware of the need. Since then I usually switch on the ignition before fitting the seat belt, and then starting. I detect no difference at all and if in a hurry I just start and go - and then fit the belt!

[Dazzler]

Hmm, interesting, my daughter's car (Lila), has recently developed a miss at start up, only after resting overnight. Could we be looking at glow plug failure. These are our 1st diesels so I don't know much about them yet. 

Glow plug failure usually results in excess smoke at startup..are you getting that?

[rustynutz]

Found this 2 part article which diesel owners may find interesting: 

http://autospeed.com/cms/title_Common-Rail-Diesel-Engine-Management-Part-1/A_108104/article.html
http://autospeed.com/cms/title_Common-Rail-Diesel-Engine-Management-Part-2/A_108105/article.html

In regards to the thread topic, it has this to say about glow plugs:

Common rail diesels still use glow plugs, however their use is not normally required except for starting in ambient temperatures below 0 degrees C.