Diesel engine cars?

When you turn the key in the ignition (Before you start it up) all the lights come on i.e Handbrake, airbag and oil, There is a orange light which represents the heater plugs. Ive been told that if you swith the engine on before the orange light goes off, it can cause damage. is this true?

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  • 1 decade ago
    Best Answer

    It will cause damage to the glow plugs.Starting it before the light goes out will eventually start to swell the tips of the glow plug making them hard to remove making the tip break. this tip could break off and bounce around in the combustion chamber And could get lodged in a valve port. When the valve closes it will cause the valve to break. So yes it could. wait for the light. the light stays on longer in cold weather. the reason for these glow plugs is to pre heat the fuel.Diesel won't ignite or burn unless it is at least 125 degrees

    Source(s): Mechanic for 20 yrs.
  • 1 decade ago

    I don't think this is true. The light comes on while the glow plugs are heating - the glow plugs are there to help the engine get started from cold, as a diesel engine works on compression rather than sparks to ignite the fuel.

    A relatively new diesel car won't even have this feature anymore, as direct injection diesels don't usually need it.

    Older diesel cars (particularly ones without a computer system to manage the engine) will always show the orange glow plug light for a set amount of time, as they usually aren't intelligent enough to know whether it's needed or not.

    If you try to start the engine in the middle of winter (in the UK at least) without waiting for the light to go out, the engine will probably struggle to start for longer than if you'd waited, and so you''re more likely to run down the battery. In warmer weather, when the engine block isn't likely to be at a sub-zero temperature, you can probably carry on without it.

  • 1 decade ago

    Wikipedia just says this;

    In very cold weather, diesel fuel thickens and increases in viscosity and forms wax crystals or a gel. This can make it difficult for the fuel injector to get fuel into the cylinder in an effective manner, making cold weather starts difficult at times, though recent advances in diesel fuel technology have made these difficulties rare. A commonly applied advance is to electrically heat the fuel filter and fuel lines. Other engines utilize small electric heaters called glow plugs inside the cylinder to warm the cylinders prior to starting. A small number use resistive grid heaters in the intake manifold to warm the inlet air until the engine reaches operating temperature. Engine block heaters (electric resistive heaters in the engine block) plugged into the utility grid are often used when an engine is shut down for extended periods (more than an hour) in cold weather to reduce startup time and engine wear.

  • 1 decade ago

    No, but the orange light goes off when the diesel is sufficiently heated to start the engine, if you crank the starter before the plugs have heated up you are just wasting fuel, I suppose you also run the risk of flooding the engine, though I've never seen that happen. If it's very cold, zero or less degees C then the engine won't start.

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  • 1 decade ago

    Yes this is true as unlike spark plugs on petrol engines deisel engines use glow plugs which need time to warm hense the orange light on the dash, take for example you were heating a peice of metal to make it glow, it wouldnt glow instantly but would under a short period of time, thats the same perspective a glow plug works under, therefore meaning it needs time to warm up so they "glow" and yes it will shorten the life of your plugs if you do not allow them to warm up but is highly unlikly to cause major engine damage.

  • 1 decade ago

    Apart from stressing the battery turning over the engine, in my opinion it makes little or no difference. I have driven diesels for years, frequently forget to wait until the light goes off and have had no issues.

    Source(s): Personal experience
  • 1 decade ago

    No, the light indicates when the glow plugs are up to temperature. All it will mean is in the cold weather the engine will either stuggle to start or not start at all

  • Anonymous
    1 decade ago

    ive done it in mine and it cut out down the road, then wouldnt start for a few minutes. probably best to wait until it goes off

  • Anonymous
    1 decade ago

    it wont start thats all glow plugs r cheap enufff to replace

  • 1 decade ago

    yes it could damage the glow plugs

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