Just bought my first diesel car, a Peugeot 306 1.9 (not the turbo model) and not too sure about this waiting for glowplugs to warm up malarky.
In my job I spend all day driving but tend to stop every mile or so for a few minutes, consequently my engine is always warm. I know when starting a cold engine I need to wait for the glowplugs to heat and and dashboard light to go out.
Does the same apply with a warm engine? I find that the car starts fine straight away when warm without waiting for the light to go out. I am worried that although it starts fine I may be doing some damage to the engine. Bear in mind that I probably stop and start my car
There was a thread about this a little while ago. On it was said that the glowplugs, whether they make starting easier or not, are there for emissions purposes. I queried whether my engine, which starts fine even from cold without the glowplugs, required them for emissions purposes but got no reply. Apart from this I cannot see why there should be any detriment if the engine starts quickly without them.
Tom wrote in news:0adig2pijqu0vp3ni1b0havbhmljspi7jg@
4ax.com:
I can leave mine for a couple of hours and it will start instantly without waiting for the glow plug light. No damage is done. Ignition is achieved by the heat of compression, all the glow plug does is help create that heat quicker in a cold engine.
the plugs probably stay on for the same amount of time no matter what They stay on even after the light is out for a while depending on temperature. Therefore I would think that less overall load might be required from the battery to start the engine if you wait for the light to go out.. same as if you hold the clutch down the starter does not have to crank the gear box. ( Which might make your battery last longer ) Someone who actually knows if this is true might be along shortly.
I think this theory depends on the car. On some vehicles pressing the clutch pedal slows the engine, denoting that the release mechanism has an appreciable drag. Is this more or less than that of the gearbox? Probably depends on the temperature of the gear oil, but I suspect that the clutch is often more of a drag than the gearbox, so pressing it at startup would be detrimental.
Modern high pressure and common rail diesel engines only require the glowplugs when it's really really cold. They still have them fitted and at least some modern diesel engines switch and keep the glowplugs on for a while after starting anyway to make the fuel burn more completely and reduce emissions.
A non turbo 306 Diesel is not a modern diesel engine. It requires the glowplugs to warm it up before starting from cold but will start fine and without damage without preheating when warm.
I've wondered that myself. The 9-3's handbook says dump the clutch (as in, all the way down) when starting. This may be to prevent you from starting it in gear, since you have to leave it in reverse...
I missed it. But as others have said, modern diesel engines only warn you about the glowplugs being in use when it's proper cold. Below freezing proper cold. Continental European mountains in the winter proper cold. They don't need as much pre-heating as indirect, mechanically injected diesels.
Now, trying to start an indirect injection diesel when it's at freezing point with no glowies, that's something to be missed - unless you like breathing in that lovely grey cloud of unburnt diesel...
More modern diesels run the glowplugs for a while until the cylinders have warmed through properly, so the fuel burns more completely, so less smoke. I can't see how on any it would hurt to just start the car, provided it does so easily. After all, the plugs spend their life in the combustion chamber getting hot...
I would doubt it's anything to do with emissions as glow plugs have been around since long before anyone gave a toss about emissions. And if it did have an effect surely it would be only for the first seconds of running?
I've had lots of company diesels, all have had glow plugs and you really did need to wait for the little light to go out. But now I have a 55 plate C5 and that doesn't appear to have glow plugs. There is no light (although the manual shows where it is, it ain't there in reality) and it makes no difference hot or cold, it starts first flick, no need to wait.
Anyone know if this is correct, no glow plugs, or is it really beefy ones that only need a few milliseconds and they're ready to go?
I've heard specific instructions _not_ to do this on some cars, but damned if I can remember which. Might have been Triumphs... ISTR it was something to do with increasing the wear in the thrust bearings (which were a problem on Triumph engines, but they face the opposite way) before the oil has a chance to circulate.
"Due to the [approx. 3 minutes] post-heating, during the warm up phase the diesel fuel is burnt more fully and with less noise. In this way, clouding of the exhaust gas is reduced by up to
40%. The engine runs quieter from the beginning on, and the exhaust gas emissions are considerably reduced. Due to the quieter engine running during the starting phase, the life of the engine is improved."
Are you saying then that this is the system that Citroen use? It explains the "environmental" bit, but then it does say 2-7 seconds to warm up, which sounds similar to old style glow plugs. Even 2 seconds is a lot more than it takes to turn the key from "ignition on" to "crank the engine", 7 seconds is an absolute eternity. To cope with those sorts of timescales I would think it would require a light to say "hang on a while, I'm warming up", whereas what I'm saying is there is no glow plug light anymore and the engine starts instantly in the time it takes to rotate the switch from "ignition on" to "crank the engine", hot or cold. This is completely different to my last car, Mondeo 1.8TD, where you only turned the key straight from "ignition on" to "crank the engine" if you wanted to annoy the neighbours as it took ages to actually start and when it did, the surroundings completely disappeared in a cloud of fog!
(Sorry, I shouldn't be using the word "ignition", I know it's a diesel, but you know what I mean!)
I have heard a rumour that on VWs that the glow plugs are started by opening the driver's door, so that they are fully warmed up by the time you've managed to put the key it. Could Citroen be doing something similar? Certainly merely unlocking the doors with the remote causes the suspension to whirr into action so I guess it's quite possible it could fire up the glow plugs at that time. Anyone know?
The C5 does some pretty jazzy stuff when there's nobody around, I don't know what it does when you open the door but the reason it doesn't need pre heating with the glowplugs is that it is a direct injection design. The fuel gets squirted directly into the cylinder at high enough pressure that in normal ambient temperature it goes bang straight away. The glow plugs will help emissions for a while after starting.
A Mondeo 1.8td uses a horrible old indirect injection design. The fuel is squirted into a pre chamber before it gets to the cylinder. The pre chamber is too cold to allow ignition, all the heat gets drawn away into the metal of the engine and it won't start. The glowplug warms up the air/fuel mixture to a point where it will go bang. If you turn over an indirect injection engine without using the glowplugs when it's cold, the fuel that is injected just comes out the exhaust as black smoke.
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