Anonymous
Anonymous asked in Cars & TransportationOther - Cars & Transportation · 1 month ago

Can I start a diesel car before the coil (glow plug) light come on or do I have to wait till the coil light comes on first before I drive?

10 Answers

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  • Anonymous
    1 month ago

    Read the instructions.

    You certainly don't understand well.

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  • 1 month ago

    The glow plug light should come ON to show it is working and go OFF when it considers it has done its job.  That's when you start it. 

    Having said that, many diesels will start without you waiting for the glow plug. Mine will, except in extremely low temperatures. 

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  • Anonymous
    1 month ago

    When cold(like from sitting overnight not running)-you snoring... so 6 hours or longer engine has not been running. Summer or winter that is called COLD.  I don't care if it is 100F outside and the car is sitting in the sun.  It is cold as the car temperature is 180F+.  

    .    So a glow plug works like an electric stove or electric heater where you can see the wires get red hot.   The glow plug does the same thing...glowing red hot.  Then you wait till the dash light shuts off(it works like the house furnace thermostat...it senses when the room has reached the hot temperature so it shuts off. AT THAT INSTANT YOU TURN THE KEY FARTHER SO THE STARTER MOTOR ENGAGES TO TURN OVER THE ENGINE. That is how you start a cold diesel.

    A hot diesel is one that has been running within the last hour or 2 and the glow plug light will not come on as it senses the glowplug area is warm enough so you can just continue turning the key to engage the starter motor.  It starts up.  That is how you start a hot diesel.

    In both cases you do not touch the gas pedal.

    They may have on the dash or near the shifter a knob with the letter "S" on it.  This is essentially the choke (it advances the injection timing by a hair) which makes cold starting easier and faster.   I just say "choke because old cars had a manual choke valve for the carburetor...essentially the same kind of knob.  To richen the fuel at cold starting. Once it is running then you shove it back in about half way for 5 minutes and later all the way in.

    You do it this way to start faster otherwise you burn your starter out and your battery gets worn out faster.   Your diesel should start near instantly.

    • The Devil
      Lv 7
      1 month agoReport

      There is no spark to advance in a diesel. Choking it enriches the charge, but does not advance the timing.Compression fires diesel by concentrating heat in the cylinder.

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  • 1 month ago

    The colder it is, the more important to use the glow plug.  Think of it like an old manual choke.  Some times you need a little, sometimes a lot, sometimes none at all.

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  • 1 month ago

    The glow plug light should come on when you turn the key to the ON position. You crank the motor over once the light goes out to let you know the glow plugs are ready. 

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  • F
    Lv 6
    1 month ago

    Unless the weather is very cold, it’s pretty much instantaneous . I have a petrol car and a diesel, I just start them both the same.

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  • 1 month ago

    a diesel engine works on compression ..it compresses the fuel till it explodes ..no spark requires ..it works better in warm cylinders ..hence the glow plugs ..warms the head area ...it will always start easier if the plugs are used 

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  • Rick
    Lv 7
    1 month ago

    Sometimes I forget on my pickup, it still starts but your have to crank it longer and it does not run as smooth when it does start. It also smokes more. 

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  • Anonymous
    1 month ago

    Read the owner's manual.  In my diesel truck, the manual says to turn the key to ON, coil light should be on, wait for it to turn off, then start the truck.

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  • 1 month ago

    Like my favourite beverage of choice likes to state, all good things come to those that wait.

    So with that in mind, wait for the plug to warm up first.

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