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Can I leave my engine on all day ? Watch

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    I am going to be working outside today and it's incredibly cold. The lucky thing is that I am able to sit in my car and do my job from there, so my question is what precautions do I have to take to make sure my car doesn't die on me when it's time to drive home. I'd need the engine on to be able to put the heater on so that I could keep warm in this horrible horrible weather.

    My car is a Vauxhall corsa
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    (Original post by Redbed)
    I am going to be working outside today and it's incredibly cold. The lucky thing is that I am able to sit in my car and do my job from there, so my question is what precautions do I have to take to make sure my car doesn't die on me when it's time to drive home. I'd need the engine on to be able to put the heater on so that I could keep warm in this horrible horrible weather.

    My car is a Vauxhall corsa
    Wouldnt you be wasting fuel?
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    (Original post by Redbed)
    I am going to be working outside today and it's incredibly cold. The lucky thing is that I am able to sit in my car and do my job from there, so my question is what precautions do I have to take to make sure my car doesn't die on me when it's time to drive home. I'd need the engine on to be able to put the heater on so that I could keep warm in this horrible horrible weather.

    My car is a Vauxhall corsa
    I wouldn't risk it, can't you go inside so somewhere and work.. Like cafe?
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    It is fine to do this but you should be careful with your battery , make sure you check the indicator for the battery and make sure that you do not forget! , the only major issue would be if the battery dies on you and maybe the fuel , but you wont burn that much unless your actually driving somewhere.
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    (Original post by Redbed)
    I am going to be working outside today and it's incredibly cold. The lucky thing is that I am able to sit in my car and do my job from there, so my question is what precautions do I have to take to make sure my car doesn't die on me when it's time to drive home. I'd need the engine on to be able to put the heater on so that I could keep warm in this horrible horrible weather.

    My car is a Vauxhall corsa
    Buy a battery powered heater?

    Leaving your engine on would waste fuel and might not be good for it in the long run
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    What an absolutely ridiculous question. You're using around 0.1 gallons of fuel an hour when idling, meaning you'd run out of fuel in about 10 hours. Not only that, but you're causing unnecessary engine wear without racking up any miles on the clock. You'll also be contaminating your oil which will need changing pretty much straight after making such a ridiculous decision.

    Don't do it. Go somewhere warm.
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    This would invite trouble. I was stuck in a one hour traffic standstill on the M40 yesterday evening, caused by an accident.

    The five or six cars that remained, broken down, when it cleared (some in the centre lane) were, I'll bet a shilling, mainly ones that had left their engines running for the whole period.
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    yeah i used to leave engine on to warm the car up, not a good idea as it wastes fuel apparently
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    You'll obviously burn fuel so from an environmental point of view it's not great, and (depending where you are) it might be quite annoying from a noise point of view, but you're not going to damage the engine. With the engine at idle you're not going to be causing any significant amount of wear and you're certainly not going to be causing oil contamination. There are better options if you were to be doing it on a daily basis but as a one off it's not going to do anything. Trucks do it all the time.
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      I'm a bit confused by some of the replies here. How does idling an engine damage it? They're designed to be run at redline once warmed up with no problems. You can sit on a motorway at 3k rpm for as long as the fuel tank allows with no issues. So why would having minimal fuel and no load going through the engine cause it to fall apart?
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      (Original post by FXX)
      I'm a bit confused by some of the replies here. How does idling an engine damage it? They're designed to be run at redline once warmed up with no problems. You can sit on a motorway at 3k rpm for as long as the fuel tank allows with no issues. So why would having minimal fuel and no load going through the engine cause it to fall apart?
      It's not damaging it, per se, but it is causing unnecessary wear without increasing the mileage of the car, primarily down to overheating. It's also causing abnormal wear on various other parts of the car, as things aren't heating up to how they've been designed to get.

      In addition, the engine oil will be getting contaminated which wrecks the viscosity.
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      Thanks for the replies everyone, I'm sure you'll be happy to hear that I didn't keep my engine on all day. My car was surprisingly alot less cold than it was outside so that helped, I also bought a blanket with me.
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        (Original post by IWMTom)
        It's not damaging it, per se, but it is causing unnecessary wear without increasing the mileage of the car, primarily down to overheating. It's also causing abnormal wear on various other parts of the car, as things aren't heating up to how they've been designed to get.

        In addition, the engine oil will be getting contaminated which wrecks the viscosity.
        That still makes no sense. What parts of the car are wearing when it's not moving?

        The engine will only overheat if it's got a fault and you happen to be in Dubai in the summer.

        How does the oil get contaminated any differently to when the car's moving?
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        (Original post by FXX)
        That still makes no sense. What parts of the car are wearing when it's not moving?
        The cooling system is designed to work properly when the car is moving. Any incipient fault (in a fan, say, or a thermostat) will cause overheating, potentially wrecking the engine. The battery charging system is another source of problems in these conditions, leaving the battery flat.

        This is why stationary cars left with engines running in long traffic jams are disproportionately likely to break down during or immediately after that jam.
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        (Original post by IWMTom)
        It's not damaging it, per se, but it is causing unnecessary wear without increasing the mileage of the car, primarily down to overheating. It's also causing abnormal wear on various other parts of the car, as things aren't heating up to how they've been designed to get.

        In addition, the engine oil will be getting contaminated which wrecks the viscosity.
        I'm with FXX on this, idling an engine really isn't going to be putting any wear on the car.

        I'm kinda curious to know exactly why idling will be causing all this oil contamination, and just how you 'wreck' viscosity...


        (Original post by Good bloke)
        The cooling system is designed to work properly when the car is moving. Any incipient fault (in a fan, say, or a thermostat) will cause overheating, potentially wrecking the engine. The battery charging system is another source of problems in these conditions, leaving the battery flat.
        Assuming we're talking about a car built sometime after the 1960s keeping the battery topped up simply isn't an issue - that's one of the reasons for using alternators instead of dynamos. As for overheating, that's only going to be an issue if there's something already wrong with the cooling system. I have a fairly hot running 3.8 in my car in the US and never turned it off whilst crawling through traffic in Miami or Orlando and the only time I had a cooling issue was when the fan relay failed. The first symptom of that was the air con turning off!
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        (Original post by CurlyBen)
        As for overheating, that's only going to be an issue if there's something already wrong with the cooling system
        What do you think the word "incipient" in my post meant? :rolleyes:

        If you have a fault in your car you want it to be discovered in the least damaging (and cheapest to fix) way possible. It is better to discover your cooling system doesn't work when the car is moving than it is to have the engine seize in a traffic jam. It is better to have a breakdown at home on the drive than it is to be stuck in the centre lane of the M40, causing chaos and further delay to thousands of people who have already been sitting stationary for an hour.
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        (Original post by CurlyBen)
        I'm with FXX on this, idling an engine really isn't going to be putting any wear on the car.

        I'm kinda curious to know exactly why idling will be causing all this oil contamination, and just how you 'wreck' viscosity...
        Anytime the engine is running, it is being worn - that is a simple matter of fact.

        Running an engine at idle for long periods of time allows for greater chance for fuel to enter the oil and contaminate it, which basic chemistry would tell you damages the viscosity and thus does not lubricate the engine as well as intended, meaning further wear due to contaminated oil.

        As I know your next question will be "how does the oil get contaminated?", I'll pre-emptively explain:

        When idling, the crankcase pressure is significantly lower than designed use, therefore a greater pressure differential between the pistons and the crankcase, resulting in leakage past the piston rings - this combined with a slower piston speed and timing means there is significantly more time allowed for the air/fuel mixture to pass the rings and contaminate the oil.

        Understand?
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        (Original post by FXX)
        That still makes no sense. What parts of the car are wearing when it's not moving?
        The entire powertrain will be wearing, albeit some parts slower than others. Long idle times create a long term issue - doing it once or twice won't be catastrophic.
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        (Original post by Redbed)
        I am going to be working outside today and it's incredibly cold. The lucky thing is that I am able to sit in my car and do my job from there, so my question is what precautions do I have to take to make sure my car doesn't die on me when it's time to drive home. I'd need the engine on to be able to put the heater on so that I could keep warm in this horrible horrible weather.

        My car is a Vauxhall corsa
        That's totally okay in my opinion, but don't do it excessively on a daily basis. I am a student in Automotive Engineering and from my studies, petrol engines can wear prematurely if its idling for prolonged period of time. Petrol or x-Octane is pretty harsh on engines. They make for good solvents so if you are idling your engine continuously or repeatedly on a daily basis for a prolonged periods of time then that's actually bad for your engine.Petrol can dissolve engine oil from the Cylinder bore which causes the pistons to wear out the bore faster. If you want to stay in your car for a day or two, there's no harm in that, your engine will not be that badly affected. It is the continuous idling that catalyses the wear process .
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        (Original post by Good bloke)
        What do you think the word "incipient" in my post meant? :rolleyes:

        If you have a fault in your car you want it to be discovered in the least damaging (and cheapest to fix) way possible. It is better to discover your cooling system doesn't work when the car is moving than it is to have the engine seize in a traffic jam. It is better to have a breakdown at home on the drive than it is to be stuck in the centre lane of the M40, causing chaos and further delay to thousands of people who have already been sitting stationary for an hour.
        To be honest I'd much rather find out my cooling system was weak whilst the engine is at low load than whilst it's running hard (although even better is monitoring the temperature gauge every now and then to see changes before you can't ignore them). As for engines seizing, again let's talk about modern vehicles... which have things like CHT sensors and limp home mode.

        (Original post by IWMTom)
        Anytime the engine is running, it is being worn - that is a simple matter of fact.
        Wear in a modern engine is more or less equivalent to half a gnat's ball hair. That's why it's common for engines to do a couple of hundred thousand miles without so much as a new bearing.


        Running an engine at idle for long periods of time allows for greater chance for fuel to enter the oil and contaminate it, which basic chemistry would tell you damages the viscosity and thus does not lubricate the engine as well as intended, meaning further wear due to contaminated oil.
        You can't damage viscosity... it's a measure of resistance to flow.

        When idling, the crankcase pressure is significantly lower than designed use, therefore a greater pressure differential between the pistons and the crankcase, resulting in leakage past the piston rings - this combined with a slower piston speed and timing means there is significantly more time allowed for the air/fuel mixture to pass the rings and contaminate the oil.
        Understand?
        No, combustion chamber pressure will be lower than normal. Crankcase pressure is typically below atmospheric - if your crankcase ventilation system gets blocked and the crankcase starts pressurising the first thing that tends to happen is the dipstick gets pushed out. Due to lower manifold pressure (which is typically where the vacuum for the crankcase is provided from) at low throttle you may have slightly lower than normal crankcase pressure, but from atmospheric to absolute vacuum is only a difference of 15psi. Typical manifold pressure with the throttle closed would be about 4-5psi. That's absolutely insignificant when compared to combustion chamber pressure, which will reach somewhere in the region of 165psi before combustion. Post combustion pressure varies depending on the load, but will be in the region of thousands of psi. But as I've already said, combustion chamber pressure will be much lower than when it's under load (negligible torque, force x area, yada yada) so actually the pressure differential across the piston rings will be much lower than normal.
        Ignition timing will have no effect on leakage, lower piston velocity gives more time for complete combustion of fuel, much less fuel is being introduced so there's much less to leak past the piston rings...
        Understand?
       
       
       
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