Why do long haul truckers warm up their engine for 30 minutes before leaving?
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Cold parts behave differently than warm parts. Most things expand as they get warmer. Some things like belts and hoses are stiffer when cold and get more pliable as they warm up.
That means if there’s a problem with a part, that problem might not become apparent until it’s been sufficiently warmed up. For example, a belt might be tight enough when cool but as it gets more pliable it starts to slip. Or a hose might have a tiny leak that becomes more apparent when it’s warm.
Truckers also have a lot more gauges than normal cars for things like oil pressure and several different fluid temperatures. It can take a while for those things to stabilize, and they want to see where the numbers stabilize before they get going.
That’s because odds are if the engine’s been off for a while they’re at a truck stop or some other place where it’s relatively convenient to stay put and get some maintenance done. If they YOLO and hit the road and find out in 20 minutes they’re overheating, there may not be anywhere safe or convenient to stop and it will be much more difficult for them to get it fixed.
It’s also possible some of those systems just won’t work well until everything’s stabilized. Letting the engine idle while they get prepared for the trip helps eliminate a lot of aggravating issues, or at least helps make sure aggravating issues happen before they’re more difficult to address.
The big diesels have a shockingly low fuel consumption when they are just idling. Something else they are doing is building up air pressure to make sure the brakes work properly.
Most of the amenities in their cabs run off of batteries, which can be depleted quickly. They idle to avoid depleting their batteries while they get ready for their day.
All these answers so complicated. They’re just getting the climate set (AC/heat) and making sure it runs, air pressurizes, etc. Shouldn’t be idling for 30 minutes.
Edit: Oh yeah! The 30 minute part is a log book requirement if I remember right. 30 minute pre-trip inspection. I thought it was 15, but maybe it’s 30. Still shouldn’t idle for 30 minutes.
Can’t respond, but this link explains it. Truckers shouldn’t idle because fuel is expensive.
https://dragonflyenergy.com/what-is-the-best-apu-for-your-long-haul-truck-sleeper-cabin/
It’s called Proper Operating Temperature. It’s kind of self-explanatory. You can cause severe damage to the engine if not at the proper temperature before putting the engine under the strain of a load.
Even modern Heavy Engines, which have computer systems which mitigate operating at low temps still require air tanks to be filled to operating pressure and tested. Also, any good driver has a Federally Regulated Equipment Inspection they required to do before starting their work day which takes between 15 and 30 minutes.
I used to be a long haul trucker. There is no need to let a truck idle for 30 minutes before starting. A few minutes is plenty sufficient.
So many of these answers are just people guessing.
No, an idling truck is NOT surprisingly fuel efficient. An idling truck burns about a gallon an hour. This is why many trucks are equipped with diesel heaters that can keep the cab warm without idling.
This is sort of answering the why. It is because the consequences of a breakdown with a cargo truck is much more financially precarious than a random person in their own car. So, much less less is left to chance.
Because they want to show how big their freedom is …
Modern engines do not really warm up while no under load and when running cold cannot run at optimal conditions or clean exhaust gases properly.
Long story short.. its bullshit
They don’t. Most trucks have 5-10 minute idle shutoffs and company drivers who exceed 5-10% idle generally find themselves out of work. It’s heavily regulated.
I drive a school bus, which is a big diesel. Warming up and needing to idle diesels is old data. We start and stop our engines 6 to 10 times a day with zero warm-up. Regardless, idling longer than 3 minutes is illegal in my State. This might actually be a Federal regulation.
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