How long do the glow plugs stay on for?

[jmurray01]

Excuse my ignorance, but the 2007 Passat 2.0 TDI is a lot newer technology than the old diesels I'm used to!

The question in a nut shell is how long do the glow plugs stay on for? I presume they stay on longer than the 2-3 seconds the light illuminates for, but I don't know how long. The reason I'm wondering is on these cold mornings I like to let them heat for as long as possible, and on my old diesels that's simple as you can just listen for the relay clicking off, but I have never heard that on the Passat. Maybe they are quieter now or maybe my hearing just isn't good enough!

If somebody could clear it up I'd appreciate it.

Thanks.

[Whippy53]

They're pretty quick, really cold conditions just wait for the light to go out and you're good to go.

[DMitch16]

As long as you have the correct ones fitted as some are metal and some ceramic tipped, as soon as the light goes off it should signal the end of the preheat phase. Ceramics are faster only needing 2 to 3 seconds but metal usually 4 to 5 for preheat.

[jmurray01]

As long as you have the correct ones fitted as some are metal and some ceramic tipped, as soon as the light goes off it should signal the end of the preheat phase. Ceramics are faster only needing 2 to 3 seconds but metal usually 4 to 5 for preheat.

As far as I know they have never been changed, so at 136,000 miles it is probably due replacements but so far it still starts up fine, albeit with a wee bit of blue smoke on the coldest of mornings we've had here in Scotland. Therefore it should have whatever VW put in when it was new.

So what I'm gathering is that unlike my old IDI diesels which continue to heat for a pre-set amount of time (10-15 seconds) after the light goes out, the TDI only keeps them on for the length of time the light stays on for, and once it extinguishes the plugs are no longer heating. That makes sense since direct injection diesels do start much easier even without functioning glow plugs, whereas indirect injection diesels will simply refuse to start without bump starting or burning out your starter motor!!

[Renars]

Glow plugs stay on for longer then the glow plug light shows.
Its just a pre-heat phase.
But its ambient temperature that is going to determine time for glow plug cycle.

[DMitch16]

Glow plugs stay on for longer then the glow plug light shows.
Its just a pre-heat phase.
But its ambient temperature that is going to determine time for glow plug cycle.

Already said that in an earlier post - the words preheat and preheat phase were the very terms I specifically used.

Didn't mention they stay hot for a while longer after this though especially those with 'afterglow' capabilities.