Ok, here's a question... When you're using a piece of equipment, what amount of time is too long to let it sit with the engine idling? To clarify a little--If I'm loading a truck and it only takes me 3 or 4 minutes to load, I won't expect the driver to shut the truck engine off, because if he did he'd be using the starter 40 or 50 times a day. On the other hand, if the excavator is waiting 90 minutes for the truck to return from getting a flat tire repaired, it only makes sense to shut it off. Somewhere in between those extremes there's a balance point. How many minutes of idling time is worth one engine startup?
idle time I'd say ten minutes tops. With fuel prices flcuating almost daily that is lots of waste.
I used to know the answer to this, I had a 20 year trucking career that ended 8 years ago. I can't remember exactly what the shut off point is for economy, the company I worked for gave seminars on this type of thing. NJ has a no idle law for trucks, you can't idle for longer than 3 minutes. There are exceptions for temperature extremes while in the sleeper berth, but that's it. The latest model trucks I drove had a computerized engine control manager that would shut the truck down after several minutes of idling. We found a way around this, a roll of paper towels jammed between the accelerator and the dash would bring the truck up just above idle and allow it to run on those cold days!:wink2
I drove a tanker for a national bulk carrier. They had these computor controls on all the company tractors. The system would let the engines idle for eight minutes then just shut off like you turned the key off. The trick we had was to set the cruise control for the engine to run at what ever speed you wanted. This was necessary to pwer either the pump or the air compressor to unload the product.
Of course, the drivers will always find a way around the technology. I'm sure the New Jersy lawmakers had other things on their minds than what's the optimum treatment of the equipment. Will Gurt's point about the 8 minute computer setting is an example of somebody sharpening their pencil and actually coming up with a number. But those are road tractors. They're probably never going to see a day where they'll start the engine once for every two miles that go on the odometer. If I'm loading a truck, and it sits for 8 minutes between trips (just long enough for the computer to shut it off). Now it takes another 7 minutes to run two miles to the dump and back, that's fifteen minutes per trip, or four trips per hour. Four times eight is 32 trips in an eight hour day. That seems like a lot of work on the starter, for 64 miles of running. On the other hand, that's a lot of idling (almost 4 1/2 hours), too. So, I'm still not convinced one way or the other... :beatsme
I live on the coast of washington and it never gets really hot or cold enough to warrant idling for extended periods. I'd rather shut it off than let it idle for more than 2 or 3 minutes. I'm sure I probably get shorter starter life, but I get tired of listening to engines run all the time.
The manuals that come with the particular equipment probably give a suggested time, from the standpoint of optimum equipment performance vs keeping quiet for the Jerseyans living close by. I was looking up something in a manual for a machine I had rented & it was addressed in there, but I can't remember what it said now. Also gave the reasons for the times it suggested for different scenarios, but I can't remember those either. Might be time to trade in the brain for a newer model :dizzy
Digger, I'd like to know more about this topic as well. I recently posted a question regarding backhoe lifetimes and i should've added this question as well. Do you get the vibe that 10 min. or less is the "magic" number on machinery? We're still searching for the "right" answer on this one also... thanks
We leave machines running for the day in the winter. But in the summer we seem to shut them off if we are not using them after 5 mins. I would rather buy starters than have to replace worn out engines.
we've always idled for a minimum of 3 mins., or until we see the temp gauge going down. my understanding is that you're just trying to get the water/antifreeze in your block/heads the same temp as what's in your radiator so they cool down evenly and minimize the possibility of warping/cracking a head.
Dayexco- you say MINIMUM 3 minutes. I assume you're talking cool down, correct? What's your MAX. idle time during the workday assuming the machine is doing nothing? And to follow up, will you consider extening that idle period by giving a few rpms to the machine to keep the fluids moving more? thanks PS- DigDug You mentioned buying starters over replacing engines. I've heard that the start -up condition is one of the primary causes of engine wear. Am i off base here?
if the temp gauge is running on the hot side, i'll idle whatever it takes. guess i've never had to anymore than i'm guessing 5 mins.
Remember that cooling down also helps to cool down the turbo(s), I've heard some guys say it's heresay, but I don't take chances. I always idle at least 3 minutes, if not 5, but no more than 10.
Yes , start up after a long shut off period will be more wear on the machine than restarting a machine that has only been shut off for 30 mins or less. Freezing cold starting is even harder on the engine life. We leave machines running all day if its less than 30 degrees. Just to keep the engine / tranny /hydrualic oil flowing. Not to mention keeping the fuel flowing so it will not jell up. We will put cardboard over the radiator if the temps are below 10 degrees. In the summer we will normally shut the machines off if it is going to be more than 10 or 15 minutes that we will be away from them, but not always. Yes the objective to leaving the machine running after you get off is to let the oil cool the small turbo bearing. The other being to let the temperature of engine come down slowly and evenly so as not to crack / warp the head. doug
That is a pretty hard question to come up with a exact answer. Beings I drive truck most of the time I leave the truck running. The only reason being is when I’m getting loaded I need the air pressure to be consentient in the air bags as I have load gauges on the truck. If I’m out side of the truck working chaining a load or machine down in the cold I will leave it run so when I’m done I can get warm fairly fast, or cooled off which ever the weather may be. If it is going to take some time to do the work out side I will shut the engine off and then re start it about 5 minutes before I get back in. As far as our equipment goes the operators are in the machines 90% of the time and working. On really cold days on the island we will leave them run during fueling and lunch break, and even in the really hot weather we will leave the run because we work them so hard. Now if no one is going to be back to operate it for a while I’m talking like past 30 minutes then they usually shut them off.
I have run many pieces of equipment, usally 3-5 min cool down slightly above idle (to run the fan faster if belt driven, circulate more water up the oil prssure a bit). We leave many machines running overnight if very cold and now electric for block heater which is bad cause they wet stack (build up fuel in the exhaust becasue its not hot enough to burn it). Best is to watch your oil temp guage, pyro engine temp ttc figure out when they "bottom out" and hten you know when to shut it off if your lucky enough ot have gauages anymore. I know much of engine wear comes from start up metal on metal (valves etc before oil can get up there) they make kits that store a charge of oil you turn the key it discharges the oil giving you some lube before you even crank it over. Those kits allow you to shut down and not waste fuel and not have the intital start up wear.
I guess ambient operating temps make a huge difference to this question .. but in temperatures above freezing, anyone who idles for more than 5-6 mins is losing money, and creating more engine wear than a cold start. Idling generates a higher rate of engine pollutants, due to incomplete combustion .. wastes a sizeable amount of fuel .. and adds to air pollution. I've seen the total figure on the amount of wasted fuel in the U.S., via unnecessary idling, and it's a staggering amount of gallons. Excessive idling can burn tips off injectors .. is particularly bad for Cummins, due to their fuel injection system design (they need speeds above idle, to get satisfactory injection and combustion) .. causes wet-stacking, as previously mentioned (inadequate combustion temperatures create oil build-up on cylinder walls) .. and generally increases wear due to low combustion chamber temperatures. Rebuilt starters are a cheaper option .. compared to shorter engine life, higher overall fuel costs, and increased air pollution. Virtually all manufacturers have recommendations in their manuals against excessive idling.
After normal operation a 3-5min cool down is all that is needed. We like quiet zones, noboby wants to hear a machine at lunch. In the summer if the hyd oil is hot we let them idle longer. In the winter I let mine idle at a higher rpm to keep the cab warm, A warm operator is a happy operator. Some of our stuff is just plain worn out JUNK, if it is shut down it might not restart.
I thought I'd bump this topic back to the top, since I just read Rod Sutton's May 1, 2007 column in Construction Equipment, Engine Idling Wastes Fuel, Increases Wear. While it didn't really answer the specific questions I had when I first posted this thread, it does remind us of how (increasingly), important it is to know those answers. Linked at the bottom of that page, is another article from CE, and it does address in some detail, things I was wondering about. How to Stop Idle Waste of Fuel It's interesting to see that some of the replies here reflect the same concerns mentioned in the article. Thank you, Construction Equipment. :notworthy
One thing to remember is, at low idle you are not burning all of the fuel in the cylinders so you end up "washing" the cylinder walls and your oil pressure usually ends up running low which isnt for the motor or turbo. If your going to idle longer than what it takes to sit through a traffic light you should bump the idle up to around 1000 rpms.
We let them run down 3-4 minutes, warm up about the same maybe 5 min. Shut em down at lunch. I don't like start ups so if we stop to discuss the job or for any other reason less than 10 min we let em idle. I've seen guys just shut down a hot machine just so they don't have to get off to get instructions for 1 or 2 minutes. To each his own I think a little idle time is easier on the machine than starting and stopping all day long. If our day goes right the machines are started twice, morning and after lunch. DP
I arrive daily at a distribution center I pick up at in my semi, and pull up to a guardshack after directly coming off a divided 4 lane @ 55mph. They have a large "Shut off your engine" sign, that you can't miss, right at face level near the dispatch window. If I've waited in line to get upto the shack I will shut off my engine, but normally I don't have anyone ahead of me and pull fully upto the window straight away. I won't shut off my motor, and have told them this, in this case. The exhaust temp is still well above 400degrees, and won't drop down to 200 or less for a couple of minutes after just having been worked out on the highway. Shutting it down daily while the turbo is still this hot couldn't be a recipe for turbo longevity. I remember reading in one of my owners manuals that the engine should not be shut down unless the exhaust temp is below 400 degrees. After being worked hard it's suprising how long that can take, especially if it's really hot outside. In the wintertime it's not so much an issue.
It's interesting--in the article I spoke of above, there's a link to an document detailing all the no-idling laws in the country. I read the ones for Allegheny County, PA, which is where Pittsburgh is located. The law allows plenty of exceptions, and one of them is to allow engine cooldown.
Do not idle at all more than a minute or two. I went through this exercise some years ago with heavy equipment. At the time, we directed mechanics to start the iron up to an hour before the beginning of the shift, and left it to the oilers to shut it down at the end of the shift. This means that for an 8 hour shift, the equipment would sometimes run anywhere from 8 1/2 hours to 11 hours depending on when it was started and shut down. Fuel consumption was not so much an issue then as it was one of the cheaper costs in comparison to others. The big loss leader was warranty repair. If you figure that a 651E scraper should run 8 hours a day, forty hours a week and average 176 hours a month, then it will take 11.3 months to run out of a 2000 hour warranty. Now, ad in the extra idle time, say an hour a day, and that's mild I'll tell you. Then you have your warranty running out in only 10.1 months, and that warranty is quitting just when you quit having teething problems and start having more major ones. But if you figure in warranty loss and fuel consumption, particularly in a project fleet of say, 58 scrapers of various sizes, plus all the other dirt equipment, then you are tossing a bunch of money out the exhaust with the price of fuel these days. Let's see, A Cat D8N used to average about 11-13 gallons per hour normal operating-time in a shift. so that's about 12 GPH let's say. Now figure that it will average 2 GPH sitting still -- but idling, (high residual loading). So there is an extra four gallons a day if it idles two hours, 20 gallons for the week, and 88 gallons for a normal month. With fuel at 3 bucks a gallon that comes to 264 bucks a month. (I'm not responsible for the math here) This exercise came about because the company took a fleet of new 785 Cat end-dumps into a gold mine in Nevada. These were early production models and they had a ton of problems. But with company and mine supervision not being truly aware of the costs involved in excessive idling, these rigs ran out of warranty long before they should have. It cost the company hundreds of thousands of dollars in extra maintenance and repair funding because of the lost warranty hours. The company took on a fleet of 12 new Cat 651E scrapers for a dam near Denver, and on this job they started using a new system. Here, the equipment was checked by the mechanics before the shift, but was not started unless it was very cold. Generally speaking, the operator of each machine started it after performing his pre-shift inspection. The operator would shut the machine down anytime there were delays of more than a couple of minutes during the shift, at lunch time, and at the end of the shift. All the operators were trained on how to properly do startups and shutdowns. The oilers checked the equipment between shifts and after shifts, but would not start the engines unless they had to for some reason. When I received these scrapers over to the other side of the mountain, they had about 12-1600 hours of operation on them, and one of the lowest "operating hour to idle hour" rates in the company. After the warranty periods had run out the equipment analysts in the home office did the math and found that thousands of warranty dollars had been recovered by reducing the idling hours. Flush with this learning and encouraged and directed by company management I took this philosophy to new jobs in Utah where I sucessfully used it with all our equipment including a fleet of 16 new Moxie articulated dumpers. It became rare indeed to hear anything idling. Then I went into California and instructed the mechanics and oilers on a union project to do the same. Boy, the smelly stuff hit the fan there I'll tell you. Those operators weren't about to start their machines, and they weren't going to shut them off either. That was the mechanics and oilers job so far as they were concerned. I never did get that turned around on that one project, but did on the one up in Kings Canyon. The project management people on the former job were all from other companies recently acquired by the one I worked for and they did not have any ownership in cutting equipment and fuel costs and of course, the union folks had their own agenda for getting lots of overtime for the maintenance guys. When the company started a third project just to the north of us, I mentioned the resistance I encountered on this from both sides to corporate management. They made sure that the new project manager not only understood the policy on idling, but enforced it. There was some trouble at first but it was soon standard practice. The fourth and fifth projects in that area had no trouble at all over it. There are some separate issues with regard to ambient temperatures and equipment fluid temperatures to consider, and of course, there are some makes of equipment and engines that have their own quirks with regard to cooling down, idling, and coming up to operating temperature. It used to be that with the older Cat engines and some pieces of equipment, particularly scrapers, you had to get out early to get all of a spread started for a shift in cold weather. I can remember starting at 4 in the morning and still not having all twenty 651B's running by noon in Wyoming. We spent a fortune on pallets of ether and massive jumper cables. New batteries and starters weighed down every mechanic truck and my pickup as well. You truly haven't lived till you have replaced a starter or two or three on a single 651B at 30 below or a D9G with a belly pan packed full of mud and frost. But now a days, if you generally work in cold climates, it's much better to prepare your machines for cold weather starting and maintain those systems for all they are worth. As far back as 1986, Caterpillar engineers told me that 99% of the time, by the time you have moved your machine to it's designated parking spot at the end of a shift, you can shut it down immediately. As I am of the old school, I still have trouble doing that myself personally, but as a rule, I've never had any trouble with equipments spreads where it was the general practice to do so since that date. One good rule of thumb I've noticed is that by the time an operator has finished his timecard and pre-shift post-shift tickets, and gathered up all the junk he took into the cab with him, it's safe to shut down. Conversely, at the beginning of the shift, by the time he's started the engine, strapped in and has everything put away, his pre-shift ticket started, and the air system is full, he's ready to go. With the new federal and state laws concerning engine idling, and the high cost of fuel, idling is just not something you want to do. This is easy if your equipment is newer and still tight, most of the new stuff starts like a dream compared to what we used to have. Good luck.
I looked through my owners manual for Mack's recommendations today, and there it stated: So it seems that fits right in with the what most have recommended and practiced. I found something else in the manual though that I thought was interesting: I would have to idle my truck for 45 minutes or more to get it warmed up that far, without some amount of working the engine. Normally I do idle about 1/2hr. I'll fire it up, do a walk around/tire/light check pretrip, and go back inside to fill the coffee etc. After 1/2hr it may be upto 150*, but no more. I've a couple miles of dirt road before I get to asphalt, which I'll run real light on the power during, and once too highway it's around 170*. Any opinions on the amount of warmup time/ engine temps before equipment is being put under full power? Gradually ease into it, or do some work em' hard right away?
Jeff, The exhaust temp is a good guage for warm up. In other words, if you are just cruising slowly with low exhaust temps, you can get your warm up while moving. I too have a long dirt road before the highway. I will often just start moving within a few minutes of start up because my exhaust temps are very low which indicates that the engine isn't really working. By moving while warming up you are also slowly warming up the tranny, rear ends etc. If you start to work it hard (producing high exhaust temps) before it is properly warmed up the damage occurs because the huge metal block is still cold and hasn't expanded enough to accept the rapidly expanding aluminum pistons which have heated up to whatever you read on you exhaust temp guage - not to mention that the oil is not yet warm enough to be effective. So basically, I don't "get on it" until my water temp is around 170+ - which means that the block is warm and so is my engine oil. I also have an engine oil temp guage which is nice for this. Hope this makes sense.
This is a Question which cannot be answered. Seen as thou different manufactures have different procedures for cold start and shut down applications. Who is right here? My Car manual states : Drive the car immediately to aid warm up? Best off sticking with the documented procedure supplied by the manufacture. Pre-lube starter motors are used a lot now for full pressure start up. I've found Cummins' K series engines don't like to idle for long. I would shut a turbo charged engine down after around a minute . One whole minute is a long time when staring at a steering wheel. Ross