Starting Diesel Without Waiting For The Light To Go Off

[sasquartch]

The correct way to start a diesel (I have a 115TDI 2005 model) as far as I know, is to turn the ignition to the 'on' position, then wait until the yellow light (glow plug light ???) goes off. Only then should you turn the engine over to start it.

 

My wife seems completely oblivious to this and don't think she's ever followed this procedure.

 

The car has always started fine but does it cause any damage not to wait for the light to go out ? The car always starts fine, even in frosty conditions although like most diesels always sound pretty rough for a few minutes until it warms up.

 

My concern is that it might harm or shorten the life of something.

Edited November 30, 2007 by sasquartch

[Smilge]

What is it with women matey?! I don't think you'll do much damage in our climate as the glow plug light is only usually on for a second and the thing always starts first turn anyway. I did notice with my Mondeo though the glow plug light has never come on except for the lamp test when first switching the ignition on so unless the temperature is below a certain value, the system doesn't bother.

[big_kev]

You could tell her to adopt the following procedure.

 

1: Adjust Make-up

 

2: Turn ignition to ON !

 

3: Check Make-up

 

4: Start Engine

 

5: Adjust Make-up

 

6: Check Make-up

 

7: Drive off

 

8: Check Make-up

 

9: Adjust Make-up

 

10: Release Handbrake

[jwilliams]

Even in cold weather I have never seen my glowplug light stay on, apparently they start to heat up from when you unlock the car so by the time you get in and put the key in the ignition they have done their job.

[RADIOTWO]

Even in cold weather I have never seen my glowplug light stay on, apparently they start to heat up from when you unlock the car so by the time you get in and put the key in the ignition they have done their job.

 

Hi jwilliams

 

No they don't work till you turn the key, but most diesels will start fine without the glow plugs but temp

will make a diffrence !

 

Radiotwo

[Dave-G]

I also read on here that the car assumes the engine will be sarted if the door is unlocked - and pre-heats the plugs...

 

without illuminating the "glowplug on" indicator in the instrument panel.

[philg]

The job of the glow plugs is to heat inside each cylinder to help ignite the diesel, if the car will fire on the first crank without waiting for the light to go out then I can't see it doing any harm not waiting for it. I never wait for the glow plug light on our Galaxy and it always fires first go. Our diesel 106 though, will not fire unless you wait for the light. When one of the plugs stopped working it would only fire on 3 cylinders for a few minutes until enough heat had conducted through the cylinder walls to the remaining one. What I'm getting at is each car is different. If yours is like our Galaxy I wouldn't bother waiting for the light.

 

The only problem I can see is wearing out the starter if it does need the heat from the plugs but you don't wait for the light, thus having the starter turning for excessive lengths of time.

[Beyond Help?]

As said, there is no 'predictive pre-warming' on opening the door or unlocking it. It is simply that the glow-plugs have two coils in them, the first one is quite fine and heats up very quickly, but only stays on for a second until the main coil glows hot enough for prolonged use. The plugs stay on after the engine is started to help reduce white smoke.

 

And if you think glow plugs are not really needed then turn the key, but not to the cranking position. Now leave it for five minutes until the plugs have cooled down and then try to start the car. Not needed?

[Beyond Help?]

duplicate post Edited December 3, 2007 by Beyond Help?

[sanjsanj]

And if you think glow plugs are not really needed then turn the key, but not to the cranking position. Now leave it for five minutes until the plugs have cooled down and then try to start the car. Not needed?

surely in the on but not started position, it would keep the glow plugs heated, ready for you to start the car???

[Beyond Help?]

And if you think glow plugs are not really needed then turn the key, but not to the cranking position. Now leave it for five minutes until the plugs have cooled down and then try to start the car. Not needed?

surely in the on but not started position, it would keep the glow plugs heated, ready for you to start the car???

No, they only heat for a minute, if the engine is not cranked they turn off. They use a fairly high amperage and if they stayed on indefinitely waiting for the engine to be started they would soon flatten the battery.

[belial]

My wife as her own car, expensive option...but worth it ^_^

[alterego]

It is simply that the glow-plugs have two coils in them, the first one is quite fine and heats up very quickly, but only stays on for a second until the main coil glows hot enough for prolonged use. The plugs stay on after the engine is started to help reduce white smoke.

 

The glow plugs on the Shalaxy TDI/PD diesel engines are not a dual coil device. They are simply heated tips which take about 10 amps each and two or three seconds to reach red hot temperature. When you turn the ignition key, the ECU works out from the engine and ambient temperature whether to energise the glowplugs and for how long - they are either on of off. The tips are situated very close to the injector spray pattern. In cold weather, and with a cold engine, particularly if the engine cranks slowly, the compression stroke may not heat up the cylinder air charge sufficiently to ignite the diesel. The red hot glow plugs ensure that ignition occurs in the vicinty of the plugs at least, once the engine starts the chamber temperatures rise quickly and after a few seconds, the ECU will turn the glow plugs off.

 

The ECU cannot check whether the glow plugs are working or not - they operate via a simple relay. The glow plug light is the ECU's advice for you to wait until it think the temperatures are hot enough for a trouble free start. The glow plugs do continue to operate for 3 or 4 seconds after the light has gone out.

 

Symptoms of a faulty glowplug are difficult starting from cold with increased smoke and rough running for a few seconds after starting. If you don't wait long enough you might experience rough or lumpy running for a few seconds.

 

AFAIK, at temperatures of 20 deg plus ambient or if the engine is warm, the glow plugs do not activate at all.

 

It only takes one or two faulty glow plugs to make starting in cold weather a pig. Unfortunately, like spark plugs, glow plugs tend to have a limited life and they are worth checking after about 30,000 miles.

 

To check the glow plugs you need to remove the engine cover, and pull the busbar rail off the glow plugs (this require a hefty tug). Check each for resistance to the engine block. They are usually 0.15 ohm to 0.3 ohm. Faulty plugs are usually open circuit or several hundred ohms plus. If you don't have a multimeter - use a 12v bulb (6w to 21W) - if it lights via a plug (other end to +12v), the plug is OK.

 

Avoid cheap glowplugs - they dont last long - sometimes only a matter of weeks. I recommend NGK, Beru or Bosch. Use a good motor factor or major company like GSF,Eurocarparts or www.vwspares.co.uk, they will be less than half the price of a dealer and will be the genuine item unlike some Ebay bargains.

[big_kev]

My wife as her own car, expensive option...but worth it ^_^

 

 

Which one, the wife or the car ?

[ninjakev]

Whereabouts is the temperature sensor for the glowplugs, and can anyone tell me if it's only used for the glowplugs and nothing else, ie not the temperature gauge. I'm still having bother with starting first thing in the morning and it's worse during the colder weather. I've replaced the glowplugs and the glowplug relay.