I think this is more of a GQ than an IMHO, so I put it here.
I don’t understand why it is such a big struggle (at least where I live) to convince truck and bus drivers not to idle their vehicles during long stops and layovers.
IIRC, way, way back in time it used to take more fuel to start the deisel engine than to keep it running, or so the theory went. But that certainly can’t be true these days and besides, after a while, even an old idling engine will consume more fuel than it takes to start the engine cold.
The only two reasons that make sense is that 1. it is somehow a struggle or long, involved process to start the engine after it’s been turned off, and 2. none of the “life support” (radio, AC, etc.) functions without the engine running. Both of these, of course, have more to do with driver comfort and convenience than safety, fuel economy or vehicle upkeep.
#1 seems hard to believe in this day and age, but I’m no truck driver, so I could be wrong.
#2 seems a little more plausable, but you’d think that someone would have solved the problem by now – enabling the driver to use all the various comfort features with the engine turned off.
In any case this is obviously still a problem because there are signs all over the place threatening huge fines for excessive idling, and very few months you’ll see some news conference about how idling trucks are pumping up the air pollution and asthma rates. I just don’t get it.
For that matter, why do motorcyclists sit and rev their motors at full blast for an hour? Why do they sit in the parking lot right outside your apartment window early on Sunday morning and rev their motors at full blast for an hour?!?!?! :mad:
Because they know you’re sleeping. They do the same thing to me.
As to the first question, there was an article in today’s local paper about emission problems.
The caption under the associated photo says:
So it sounds as if it is mainly for comfort features, rather than any difficulty in re-starting the engine.
So, how much experience do you have in starting a cold 12.7 litre diesel engine? How many restful nights have you spent sleeping in a sleeper of an unheated or uncooled truck? You want to jumpstart a big rig? Push start a 18500 lb truck?
I don’t know about motor bikes but I do know that after turning on a bus or truck engine you have to leave it idling for ages or it screws the engine. Don’t know the mechanism sorry.
Yeah, there’s that, but there’s something in the industry that just says, “Keep the engine running.” I had a roommate who would start up his gasoline pickup, and THEN load his equipment from the garage. How he stood all the fumes building up in there, I don’t know. I never found a use for his engine idling for 10 minutes before he left.
When I start up the school bus (jealous?), I have to let the engine idle for a few minutes to build pressure in the air brakes. The bus literally will not move until the pressure passes a certain point. Perhaps truck drivers keep the engine running so that it will maintain pressure in the brakes so that they can drive off at a moment’s notice. The bus takes about five minutes to pressurize, if the tanks are totally flat (rare). A semi, I’d imagine, takes a bit longer.
By the way, 18500lb is pretty light. My empty bus weighs in at 36K, with kids, it’ll push 40.
Hold on. No more posts about loud motorcycles. That’s an order. Go start your own thread.
Besides, the motorbike highjack is a complaint and deals with entirely different concerns on the part of the idler and the idlee. This thread is not a complaint, it’s a question.
So tell me more about why a truck needs to idle, you truck/bus driving Dopers. Is running the full engine (or using a ground hook-up) the only way to keep the “life support systems” functioning? Aren’t there batteries, or some other system, that can do the job while the engine is off?
I am a truck driver, and have been for over twenty years. My experience is mostly local in-city delivery work. There is no reason for trucks to be idling for long periods of time, except for the comfort of the driver, if he is stuck in his cab for a long time. With the price of fuel, at least here in Canada, I can’t see any driver who is buying his own fuel to do this. There are accessories and options that can be added to the truck to reduce the need for this.
The only exception to this is when driving in very cold conditions. If a truck sits without running for too long when it’s below freezing, it just won’t start. When I used to drive in Northern Alberta, I would leave the truck running all night, even though the company always paid for my hotel/motel room, because at -40 degrees, the poor old deisel just isn’t going to turn over in the morning.
From this article on slashdot about wireless technology at truckstops a couple days ago :
Some comments point to the long winter start up times being a factor. Others said it has to do with the extreme amount of wear caused by cold starting the engine.
Drum, just my truck weighs 18,500. An empty 53’ trailer can weigh up to 15,000. Then add 44,000 or so pounds of freight.
StuyGuy, are YOU going to be providing shoreline support at every truckstop and reststop?
My truck is equipped with something called “optimized idle” that I engage whenever I’m stopped. This will start the engine when the battery charge falls to a certain level and/or the engine oil temperature falls to a certain level. When the battery charge/temp rises to a certain level, the engine stops.
The system at a petro station mentioned in a previous post charges $1.25 an hour and does nothing to keep the engine warm or battery charged.
I’ve noticed some of the posts here mentioning ‘just driver comfort’. At high idle, my truck burns 1 gallon per hour. At low idle, 0.3 gallons per hour. And I suspect the folks dismissing driver comfort spend their nights in the winter sleeping in a heated house or apartment and their nights in the summer sleeping in a air conditioned house or apartment. Spend a couple nights this July or August sleeping in your car, okay? Would you rather have driving 40 ton rigs on the road a driver who had a good 8 hour sleep the night before or with a driver who spent the night in a sweatbox?
Well, I know, you’d rather not share the road with big rigs at all. Be nice if they’d just all go away, right? All they do is drive slowly in front of you and make wide turns.
Ranger, calm down OK? Nobody’s attacking you, we just want to know why truck drivers do it. I mean when we had the huge rig parked across the road from us and he idled the engine for 30 minutes at 5.30am 6 mornings a week, I mostly wanted to kill him but I also wanted to know why he needed to do it. From the posts here, I presume he was pressurising his brakes?
You all know of course how diesels work? Fuel ignition is accomplished through compression.
You all know that if you load an ‘cold’ diesel engine you will blow the head gaskets at a minimum. Ask any heavy equipment operator.
Your little 4 cyl gas engine will warm up in just a minute but to get a large diesel warm takes a while, lots mot metal and fluids and stuff and such.
Yes, starting an engine causes much more damage than 10 minutes of idle but where gas engines are concerned, the buildup of deposits and fouling of spark plugs and other stuff is a problem so it is not really good for one to idle an gas engine a long time. Race car engines foul out real quick, that is one reason for their constant throttle blipping. High performance motorcycles are the same.
The diesel engines do not have all the complex computer work and systems to make them tractable when cold like you average new car.
Jumping in a cold car and revving the engine while cold or jumping into highway speeds is very bad for them.
There is no bad effects on an diesel engine from long idle times.
Engines that are seldom shut down seem to last the longest. Check the pipeline compressor stations. Check older ship engines and push barges. Those people are out to make money and they do it the most efficient way. I bet they have a good clue about it.
Gas aircraft engines are carefully warmed up before flight also. I wonder why if just jumping in cold and slamming down the runway on a cold engine was as safe and good for the engine.
YMMV
Does anybody here remember the choke on cars? The manual choke? We take computers and fuel injection and variable spark advance and thermostats and computer controlled spark timing for granted. A lot of the is not applicable to diesel engines.
Bottom line, the big companies would not let the drives have auto idle or idle though the night or in extreme cold or even though lunch breaks if it was costing them more that it was benefiting them. So there are a myriad of reasons of why it is done the way it is.
Jezzus Ranger, please get the d*mned chip off your shoulder!
Both your snipey replies were aimed at me and I feel I did nothing to deserve them. I am not a truck or bus driver so I know nothing of the particulars involved with driving such a vehicle. That’s why I asked about this. There is nothing about my post that comes with an agenda. And, in fact, when Mojo tried to hijack this thread into an indictment against loud bikers I asked him to cool it. Now I’m asking you to cool it too, okay?
Thanks for the information you supplied. No thanks for the attitude it came wrapped in.
You folks are correct, I did seem to have a chip on my shoulder. I don’t want to be that sort of poster and I therefore apologise. I will try to lose my defensiveness on this topic in the rest of this thread and in future similar threads.
Prima, he was probably both charging up the brake air system (which shouldn’t take more than 4 minutes at a high idle) and warming up the engine. The normal operating range for the sort of engine we’re talking about is 175 - 210 degrees, though if you’re not jumping on the interstate with a full load you can sort of putter around when the temp hits at least 140. And if it’s cold, it can take a half hour to get up to normal range.
Stuy, I have seen mounts on some trucks for engine block heaters. Some regular cars have them too. You just plug one end of an extension cord (probably a 14 or 12 gauge) into the wall socket and the other end into the truck. These will keep the engine from freezing. I’ve never seen any sort of standard plug in for a battery trickle charger. What I’ve never seen (except for one truckstop where the Idleair System described earlier was installed) are any sort of jacks in parking areas for big trucks where I could plug a 115 vac extension cord.
Some companies do make as add ons Auxilary Power Units that tap into the fuel line and can provide 115vac, AC and Heating to the sleeper unit. These won’t keep the truck battery charged or engine warm, but do provide comfort, etc to the driver. These APUs run from $3,000 to $5,000 installed and are supposed to only burn 0.3 gallons of fuel an hour. What they are is basically a small diesel engine that turns a compressor, generator, and heats water for a heater.
To answer the OP, we don’t love to idle our vehicles. It’s just that we hate having to get jumpstarted, frozen in our bunks, or roasted in our bunks more.
Aircraft engines also need to be cooled gradually. In an airplane you can carry a little power until just before touchdown to avoid “shock cooling” then engine. Taxking to parking takes a couple of minutes, so by the time you’ve stopped it’s safe to shut down the engine.
Helicopters tend not to taxi around airports. We usually set down right next to where we want to park and scoot over. So once we’re down on the ground we reduce the power and let it idle for a couple of minutes.
Funny thing is, no one has ever explained to me what “shock cooling” actually is; just that it’s bad, and how to avoid it.
Got one on my '46 CJ, and I will have one on my '66 MGB when it’s done. And of course, piston aircraft have a mixture control. (Just don’t touch it in-flight if you’re in a helicopter! :eek: )
Okay, so why do drivers idle their engines for long periods of time during mild/warm weather? I spent five years working in the office of a branch terminal for the biggest LTL carrier in the country. I’ve seen linehaul drivers pull up at 10 'o clock on mild spring evenings and leave their tractors idling for an hour or two while waiting on freight.
The company actively discourages this practice, even for short periods of time. There’s a large poster on the breakroom wall estimating that over two million dollars in fuel were lost company-wide just from idling (bear in mind, of course, that the corporation does have several thousand drivers).
It’s a good idea to keep the engine idling if you are a bank robber who has made the extraordinarily poor choice of a school bus as your getaway vehicle.
I’m sure the diesel/big engine guys will correct me if I’m wrong, but the size of the engine has some effect on how you manage it. Reference has already been made to the need to heat up a certain mass of metal, fluids, fuel, etc.
Generally, the bigger the airplane engine/more horsepower/faster airplane the more of a problem shock cooling becomes.
I once pulled a glass (a real glass drinking vessel that is) out of a dishwasher just after it cycled, meaning this thing was steaming hot, then poured iced tea into it. There was a loud bang! and the glass split into several pieces, collapsed in a heap, and iced tea went all over. That’s “shock cooling”. Now, imagine that happening to an engine cylinder full of fuel…
Shock cooling is when the engine cools down too fast, stressing the various parts which are rapidly changing temperatures at different rates. In the most extreme cases you can crack a cylinder, but regardless it puts more strain and wear on an engine that’s already very expensive. A high horsepower piston aircraft engine driving a plane that cruises in the 180-240 knot range will need some attention to avoid shock cooling on even a hot summer day. With the dinky 100 hp Continental in the Cessna 150 I fly this is not such a concern, but the one instance I know of a cylinder being split by shock cooling was in a small Cessna flying on a day where it was -15 on the ground and the guy who owned it couldn’t be bothered to install a winterization kt, even the duct-tape version. All of which is yet another reason aircraft engines have temperature gauges for the use of the operator.
Aircraft engines need to be properly warmed up prior to flight. Ideally, you want to keep them in either a heated hangar or use an engine block heater. Cold-starting an engine in sub-freezing weather is not a lot of fun. Aside from freezing your butt off being out in the cold yourself, there are extra procedures to go through that, if not properly followed, can result in an engine fire. Even if you do these properly it still causes extra engine wear. And then you might need 30 to 40 minutes to warm it up to proper operating temperatures. Failure to warm up the engine and its lubricating oils may result in failure of the engine to run when put under load, which may result in a failure to fly at some inconvenient point like 10 feet above the runway, just after take off. Even if that doesn’t happen, you’re putting a trememdous extra stress on the engine, which is not a good thing in the long run.
(psst!Johnny, not all piston aircraft have mix controls anymore. Fuel injection is becoming more common, and the Europeans apparently have a working diesel aircraft engine now where all that is handled by computer chip, like in a car. Unfortunately, I’m still flying 30 year old airplanes where I have to worry about carbuerators)
Why am I blithering on about airplanes in a thread about trucks? (Other than being obsessed with airplanes, of course ) Because truck engines, school bus engines, and airplane engines all have something in common - they are regularly expected to pull heavy loads. Very few people load up their cars in the morning to their maximum carrying capcity. That practice is routine for aircraft, semi-trucks, and busses. If your car’s engine is only warmed up enough to provide 50% performance that’s probably not an issue as you pull out of your driveway, and by the time you get to the freeway on-ramp it’ll most likely be warmed up enough. If my airplane engine isn’t able to give me 100% I either can’t get off the ground at all or, worse yet, I fly through tree branches.
Another thing - a lot of people are somewhere between neglectful and abusive to their car’s engine. And they don’t care because they aren’t planning to keep it very long. I know a lot of people who start having engine troubles after 60,000-80,000 miles. On the other hand, my Ford Festiva 4-cylinder - certainly NOT a top-of-the-line engine - gave me 130,000 trouble-free miles because of regular oil changes, proper maintenance, and not insisting it haul 400 lbs of junk in the back without letting it warm up first (and we did use it for cargo far more often than I think the designers ever imagined). The current owner - who uses it to haul his construction supplies and tools - has ticked over 200,000 miles, still with reliable engine. Especially with today’s computer-controlled starting and fuel injection just about everyone could get that sort of performance if they only were a little more knowledgable (and gave a damn). But I’m weird - when I buy a car I expect to keep it 10 years or more, not the more typical 2-3. Since I really don’t like shopping for engines I tend to take care of the ones I own.
Thus, I would expect that the larger engines used in the big trucks (and school busses) would require a little more TLC in the starting, warming up, and proper use. After all, the big trucks don’t make money unless they’re hauling, and making money is why they exist. Nor is it profitable to have to replace either parts or engines due to excessive wear. In fact, whatever extends the life of an engine - even if that means idling all night in some circumstances - is a good thing if you want to make money from that engine. Compared to a new engine, fuel is cheap Since I share the freeway with those guys in big trucks it’s in my self-interest that their trucks are running properly and if that means a half-hour at idle to get the oil temperature and cylinders at the proper temperature and the brake lines presurrized so be it. The better they take care of those engines the longer they last, the less expensive the maintenance, and (in theory) the less they charge for freight. If the noise bothers you try telling yourself it’s really the sign of a responsible diesel-driver properly preparing his rig for the road and maybe it will help.
As for the “creature comforts” - I wouldn’t be too dismissive of those. If the dude is driving several tons of stuff down the interstate I don’t want him getting cranky because he didn’t sleep well either from heat - leaving him all groggy and sweaty-feeling with that pasty sensation in his undershorts - or from cold - all achy and numb and shivering and stiff. Road rage is bad enough in a car, I shudder to think what a bully in a semi could do. Truck drivers deserve a good night’s sleep and hot wash water just as much as anyone else. Given that they’re operating heavy machinery at high speeds, perhaps they deserve them MORE than the average office worker.
Sure, there are some bad-apple truckers out there, but the vast majority I’ve had contact with are decent guys trying to do a decent job without getting into an accident or having a breakdown.
Gosh, I don’t know - maybe someone told them the frieght would be ready to go, or they’d only have to wait five minutes, and it turns out that wasn’t correct?
I suppose another reason is that what’s warm to you might not be all that warm to a particular engine - if you have to get the engine up to a particular temperature it takes as long as it takes.
Or maybe some of them are just idiots?
But I’ll bet if a trucker is an owner he’s not idling that engine unless he’s getting some benefit out of it, since he’s paying for the fuel. But if the driver is a hired hand, so to speak, and it’s the company paying for the fuel it’s much more likely he’ll be wasteful because it’s not his money. (Except, of course, whatever thousands or millions of dollars a year a big company spends on fuel that it didn’t have to is money that couldn’t be spent elsewhere, which can have an indirect impact on things like raises and benefits)
