Why do long haul truckers warm up their engine for 30 minutes before leaving?
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My friend has a slightly bigger than average diesel car and I’ve been telling him that he needs to warm it before he leaves his house to go to work, am I wrong?
Trucker and mechanic here. It’s unnecessary and wasteful. 2 minutes should be enought to fill the air. Pre trip is best done with the engine off so you can hear air leaks. The best way to warm am engine is gentle driving. Most newer trucks have water cooled turbos so the heat cracking and oil getted burned inside doesn’t happen like it used to.
Some drivers do it to power accessories or run ac or heaters, but many battery and solar systems exist. Diesel heaters for the winter will burn 3L a day instead of 5L per hour.
Idling is also terrible for modern emission control devices. my customers that have issues and complain idle a lot. Guys pulling 65 ton b trains don’t have problems.
Step 1: throw lunch box in cab and pre trip engine compartment.
Step 2: start engine to build air supply
Step 3: park personal vehicle and get dispatch papers for the day from office
Step 4: try not to get sucked in to deep of a conversation with a bunch of lonely truck drivers
Step 5: return to truck and build air supply in trailer next.
Step 6: pre trip truck and trailer ( check 18 tires, 18 brake cans and pads, lights, fifth wheel, suspension, listen for air leaks, and check load is secured properly for starters).
Step 7: forget step one through six and sit in cab for half an hour on the clock while scrolling Reddit.
I drove truck for a year, you don’t have to warm up your engine for 30 minutes.
A lot of long haul truckers without APUs will just idle their trucks all the time for the AC/heat and electricity. There’s no need to have the engine warm for the pre-trip. You can check your oil warm multiple times throughout the day.
The one caveat is if they’re running an ancient engine that they’re still using because they’d rather have a shitty old engine that is grandfathered in and doesn’t need to meet a lot of new emissions standards. Those older engines probably run quite rough until they’re warmed up and don’t have a lot of the quality of life improvements newer engines do.
Another consideration is they are limited by federal DOT rules. They log into their driving tablets (ELD, electronic log device) and have to log that they preformed a 30 minute pre trip inspection. But it’s all theatre. They don’t actually check the oil and the brake liners everyday. So they just chill.
Been driving trucks for 20 plus years. I would prefer not to sweat and or freeze my balls off. We idle cause that’s how the climate control works, unless you have an APU installed.
5 year old: You don’t start sprinting without stretching first. Diesel engines (and trucks) which are expensive and go millions of miles, will last with stretching first.
10 year old: They don’t need to warm for 30 minutes. 10, especially in anything remotely newer (20 years), is plenty. In fact, many are so efficient anymore they won’t warm up much unless you start applying some throttle and ease into it. Likewise, they can set throttles on them to give them more to heat all the way. But it’s not needed unless you’re in some extreme conditions.
15 year old: They also have air break and suspension systems. Most can build full pressure (120lbs is the defacto standard of operational & reserve) in 10 minutes or less. But older trucks with weakened compressors or leaks might take longer. Depending on variant again, 60-40lbs of air is the bare minimum before brakes will automatically apply. Usually trucks have buzzers when they start until they build pressure, and most will come on at 90lbs or lower. Buzzer comes on when pressure gets lower (you apply full pressure of brakes at high speed and exhaust the braking system is an simplified/extreme example). Also many trucks have two air gauges–one for air reservoir, and another how much PSI you are applying to the system.
And trucks release air, or you hear those “hissssssssssssssssss” at a long idling truck because the reservoir has gotten so full (140-160lbs) it has to bleed some off.
Idling a motor for that long is actually bad for the motor . It can cause what’s called “bore glazing “
Like a lot of people had said warm up is completely unnecessary. Start up let the oil pressure build up and make is way through the turbo ,build up the air and get going . Load is good for the motor . Slow steady driving till it get to operating temperature and that’s it
Heavy equipment operators do the same thing. Anything with a big diesel engine and a lot of hydraulic systems need to be fully warmed up to operating temperature, or you risk popping a hose, seal, or gasket (or worse).
When I worked in open mines, the large machines and trucks were only ever really shut off when you were getting fuel. Especially in winter.
One thing about diesel engines is that they use compression to trigger the combustion instead of a spark. They do have “glow plugs” that heat up the fuel and make it easier to ignite. And the warmer the engine overall, the more reliable the combustion will be. So my best guess is that putting a cold engine under load (by putting it in gear & driving) could potentially cause the engine to stall.
To put it simply, the engine works better when it’s warm, and if you try to drive with a cold engine, it may not work well enough to keep itself running.
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