How long does a truck have to idle?

I let my truck cool down to below 250 degrees before i shut it down.

 

I general a modern truck does not have to idle at all. My air supply will sit in the tank indefinitely.

 

Depends. Mine generally can go from zero psi to 125 in 5 min. Air loss of 3 psi on tractor (bobtail) and 4 psi on tractor/trailer is a failure (that's per minute). Personally, I'm headed to the shop at 2 psi/min. A specialty truck (heavy haul or dump) might need more time for the air system because of the extra air bags and drop axles. Mine did when hooked to heavier (tag axled) trailers.

Now, I'm not turning off my rig while waiting for a train or traffic. As long as I'm on the road (not parked) the rig will run. Last thing I need is to have the engine not start at the wrong time.....lol.

I've never had to idle the truck to cool it down before turn off, but I run in Pac NW. Arizona etc, may be different.

 

The air pressure should last. If it doesn't, the leak needs to be found and fixed before it becomes a big problem. Regarding rail crossings and other similar situations, you don't want a big truck in front of you shutting down because there's a train in the road. If the driver does that, you may be getting annoyed while he or she starts it again (some trucks can be a bit irritable) puts it in gear and gets it moving. Additionally, it takes a lot of force to start a motor that weighs, in most cases, more than your entire car. If the driver is shutting it off all the time, that force will cause excessive wear on the internal parts of the motor and break the starter down in a much bigger hurry than otherwise. There you go...more heavy metals to be disposed of...

If you are asking on this forum about idling in general, most of my idle time is for my health and safety. The air conditioner does not operate unless the engine on my truck is running. The past few nights where I've been have not cooled below 85 degrees ambient outside temperature with a significant humidity level. I simply cannot get adequate rest if I'm awake wiping sweat off myself all night. Me without proper rest puts you and your family in direct jeopardy when you're driving next to me the following day.

Therefore, the answer is yes, often it really is necessary to run the truck all day. And sometimes, all night as well. I hope you're not asking this question so you can get an excuse to shut trucks off while there is something living and breathing inside it.

But thank you for asking.

 

Mine runs from the time I leave till the time I arrive home(2-3 weeks)
I know my truck very well and have no need to do cavity search PTI's everyday.

 

I've looked at a cost analysis of running an apu: it actually winds up costing more to purchase and maintain an apu than run fuel through the truck's motor.

Also, if it's pollution you are concerned about, you might want to rethink that apu idea. This truck and all trucks built after 2006 are required to have what's called a DPF installed in the exhaust system. DPF stands for Diesel Particulate Filter. It works by collecting all that stuff you don't want in the air in a ceramic filter and then burning it off periodically by injection of diesel into the filter chamber. What comes out that stack is cleaner than what your car puts out.

An apu is not hooked into that filter system and it is not legal to do so. Any tampering with that DPF will not only cause huge problems for the unit itself, but cost the tamperer and the driver each a hefty fine. Therefore, what that apu is pumping out is pure, unadulterated, filthy pollution. It is actually cleaner now to run the truck than run an apu. Which is why California issued "Certified Clean Idle" standards that when a truck meets those standards, it gets a sticker and a pass on the idling laws in Cally.

Most apu's are exhausted next to the front drive tire....or out the side by the bottom of the cab. I had an apu in my last truck. It did save fuel, but it also gassed me out on occasion when the wind wasn't blowing right. I couldn't imagine what it was like for those who had to park next to me on the exhaust side.

How much sense would it make to force companies to use a piece of equipment that pushes out dirtier exhaust and costs more money in the long run just because of some incorrectly perceived ideas about pollution? And how much more money do you want to spend at your local stores...who will cover their shipping costs by passing it on to the customer? Just a thought.

 

Injun the APU you had was in the wrong place if you were getting exhaust fumes in the sleeper from it. Also you looked at the wrong cost analyis. It takes about a year for a OTR truck that's out a month or so at a time to pay for itself . Yes that inculdes a Thermoking APU. A truck engine burns about a gallon a hour. An APU burns maybe a quarter of that and thats if its working hard. Also an APU reduces maintaince costs by lengthing the intervals on things like inframes or complete rebuilds. If a truck has a APU the only time I can see letting the truck run is when its 15 degrees or lower to keep the fuel from gelling.