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We all know that it is not recommended to idle the powerstroke engine for extended periods and the owners manual for my 6.7 Cummins which is in my motorcoach says the same thing. My question is this. What is the difference in the engines in over the road trucks than the two mentioned above? I ask this question because at the local truck stop which I frequent for gas and others at night there are always around a hundred or so big rigs idling away and they do so all night long. What makes it ok for those engines and not ok for the ones we drive?
Idling causes crankcase diluation, big trucks have big crankcases.
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'93 F-250 IDI, 4x4, K&N, no soup bowl, stock, with 265,XXX miles 5 speed, 3.55, kind of new LUK clutch, runs great, starts great, it is great. The truck is getting old.
Big rigs do not idle at night . They probably run 1000 to 1300. Some of them have programs where they rev up for a short while then idle back to where they are set. If you parked and let one just idle the engine will cool down too low.
In an air-throttled gas engine, the air:fuel ratio is close to stoichiometric (14:1) all the time -- idling, pedal-to-the-metal and everything in between. When ignited, it burns at about the same temperature every time and torque is controlled by reducing the amount of air admitted into the cylinders.
In a fuel-throttled Diesel engine, the air:fuel ratio is likely to be 100:1 while idling. With no intake-air throttling, it's gets a full charge of cool air every time and with just enough fuel to keep the engine idling and power accessory loads, the combustion temperature might not be much higher than thermostat temperature. The excess air dilutes and drastically cools the cylinder charge.
I'm a little befuddled as to why all-night idling even still exists. An idling 10 or 12-liter engine consumes a gallon per hour; given the current price of Diesel fuel, you could pay for a room at Motel 6 and have change left over. (even before considering the extra wear & tear on the engine and transmission front shaft)
Old habits die hard, I suppose.
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Douglas Campbell [drcampbell ot engineer dat kahm]
November 5, 2008: The fat lady sang. Back to actually working for a living.
1986 Isuzu P'up, 177,673.8 miles. Hella headlights, (highly recommended) DOT C-2 back end. (also recommended) R-12 air conditioner converted to R-406a. 4.1:1 rear axle converted to 3.4:1.
9/22/2007, age 21: Still running well when reluctantly sent away for reincarnation, due to body & frame rust.
A few trucks are now just running small generators that can power their TV, coffee maker, running lights so the drive engine doesn't have to run at all.
What is the difference in the engines in over the road trucks than the two mentioned above?
Actually none. I agree, all the mfgrs say don't do it but through the years I've found most everyone does it with no ill effects, from Powerstrokes on up even before the days of a fast idle feature. Diesels can always idle on less fuel consumption than a gas engine, so even with the high price of fuel, a guy staying in his sleeper is still money ahead compared to motel rates nowdays. I drove a cattle truck for a few months as a favor and personally I shut my truck off, but most of the other guys would just let theirs idle for 3-4 hours while cattle were being separated, loaded, etc, and the only ill effect was puking out a lot of blue smoke for a few 100 yards as they took off. On the other hand, after I retired, I drove a set of these for 3 years Reliance Trailer - Transfers and if you let it idle more than a couple minutes you received a severe butt chewing from the owner, so everyone has a different opinion. A friend builds ranch fence for a living and due to his line of work his IDI's and Powerstrokes have way more idle time each and every day than they do going down the road and he gets great engine service from them. One theory (from a heavy truck engine rep) for letting them idle rather than shutdown is that more engine wear occurs from engine temp change caused by shutdown and then startup compared to letting it idle, so who knows?
I'm a little befuddled as to why all-night idling even still exists. An idling 10 or 12-liter engine consumes a gallon per hour; given the current price of Diesel fuel, you could pay for a room at Motel 6 and have change left over. (even before considering the extra wear & tear on the engine and transmission front shaft)
Well for one thing, ever try to put a 65 foot long truck in a Motel 6? , not many motels offer truck parking. Plus there are none within 100 miles of where I have to deliver most of the time.
As far as extra wear and tear, it is minimal at best, out of 24,000 hours on my Cat diesel, there are 6000 hours idling, in 9 years.
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A few trucks are now just running small generators
Those small diesel generators use .5 gallons per hour, and at $10,000 each are not quite the bargain the manufacturers claim that they are, at least in my operation. Plus they weigh in at almost 500 pounds, which some states will give you an extra 300 pounds.
No easy answer to the idling for the comfort and safety of the driver, not until they start using some kind of shore power.
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2002 F-350 SC SRW long bed 4X4 7.3 PSD Auto, Island blue,
38 Chev sedan delivery all steel, 350, TH400,A-C PW PS PDB, Yellow,
2000 Kenworth W900 600Hp Cat 18 spd 3:70 green [color:"blue"]My pics [/color]
Ever notice the UPS delivery trucks. they never let them idle. shut em down at every stop. those trucks get some good amount of wear and tear on the starters .
A gallon or two each day that wasn't burned because they didn't idle adds up pretty fast.
Ten weeks of not idling will pay for a starter. Seems like a no-brainer to me.
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Douglas Campbell [drcampbell ot engineer dat kahm]
November 5, 2008: The fat lady sang. Back to actually working for a living.
1986 Isuzu P'up, 177,673.8 miles. Hella headlights, (highly recommended) DOT C-2 back end. (also recommended) R-12 air conditioner converted to R-406a. 4.1:1 rear axle converted to 3.4:1.
9/22/2007, age 21: Still running well when reluctantly sent away for reincarnation, due to body & frame rust.
As far as extra wear and tear, it is minimal at best, out of 24,000 hours on my Cat diesel, there are 6000 hours idling, in 9 years.
Couldn't agree more. Theory and "they say" is one thing, what actually happens in real world use is another. A buddy was in a bind for help last week and he had me go over to Moorcroft, Wy to run a boom truck owned by the company he subbed to for use on his rebar caisson job. It is an old IH 4300 Transtar with a 400 Cummins and I slow idled it 8 hours/day for 5 days straight lifting and moving steel, and other than going to jobsites, that's the way the truck's used year after year on caisson/foundation jobs. I think if the company foreman was there and someone dropped by to imform him of the evils of longterm idling or the dreaded "wet stacking", his advice to them would go WAY beyond telling them to take a hike.
Then of course there was the flat bed out of S.D. that came in twice with 2 25ton loads of rebar that sat ildling both times while I unloaded him.
What about wet stacking? I wouldn't want to pay for the wasted fuel of running all night. I imagnine a lot of these guys running all night do it because they have a company gas card and don't care about cost. As far as running a smaller generator I can see why you would do it. If you spent much time idling it would pay for itself pretty quick if you were buying your own fuel.
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Sold, 97 F250 Supercab back to the 85 S10 and loving it.
I agree
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