Leave engine running while fueling?

[Rkloud9]

Was gassing my minivan today, and a fellow next to me was fueling his Cummings diesel powered pick-up with the engine running. Thinking this might be a safety hazard, I asked him why he left his engine running... he says

"This motor is turbo-powered, and the turbos need careful cool down. It's better to leave the engine running. I have been an over-the-road driver for many years, and this is how you treat a turbo-powered diesel engine."

I ask him about safety concerns, and he says the diesel running temps are lower, and there is no fire danger.

OK, gang, what do you think? Should we leave our Sprinter motors running while we fill up?

Starting the corn popper right now!

Bob & Cynthia
2017 SunSeeker MBS 2400W
150 days and 24000 miles since April 2016.

[elchilero53]

And the sign clearly states to shut down your motor off before fueling. Cooling down the turbos? That's a new one on me!!

[KFX450RXC]

If he hadn't been towing anything, it was probably not necessary.

But safe? Yep. Gasoline flash point is anything above -45 F. Diesel flash point is at least 126 F. I doubt it was 126 degrees outside at the pumps.

[dwhit]

I let the diesel idle for oil cool-down. That turbo bearing costs a lot! Too quick a shut-down MAY coke the oil lubing bearing.

[hkreck]

Was he also smoking while talking to you and fueling? I know Diesel has a high flash point than Gasoline but the fire hazard is still there. 32 years in the fire service and I could tell you stories about truck drivers.

[mwdilday]

The issue would be more the people pumping gasoline next to him. Still a risk. And yes turbos need to idle to Cool down after towing.

[TheWolfPaq82]

Diesel fuel actually falls into the category of "Non Flammable Liquid" due to it's high flash point of 125 to 205 degrees.

[Skyliner]

Turbo cooldowns are important if you want to get more than 100k miles out of your turbo. I have 3 turbo'd vehicles in my household and one of them is at 197k miles and running strong.

I don't have an issue with diesels idling when refueling. However, I do have an issue with gassers doing this. Fuel vapors displaced by filing an empty fuel tank are easily ignited by static electricity, sometimes cell phone use, vehicles with distributor caps, and folks running a propane fridge.

[Kenny kustom]

Depending on time of day, or situation, I often left my diesel running while filling.
Coming right off the highway, or in the stone cold dead of winter, where I’ve just started it and drove the 3 blocks to the fuel station.

[NMWildcat]

We always leave our diesel idling while fueling. Sometimes to let the turbo oil cool down and cycle, but usually to leave the a/c on for DW.

Never had anybody question me about it.

[18CrewDually]

After coming off the highway I always let it idle until the EGTs are down to about 350 and oil temp down to 190°. Usually about 3 minutes allows it to cool enough to ensure after shut down the center section doesn't cook the oil around the bearing which can result in failure.
I rarely if ever shut it down while refueling.
Gasoline vapors are explosive with a Flashpoint of -40°. Diesel is combustible needing heat or compression to light. Diesel Flashpoint is around 150°+/-.

To add, the dangers of diesel are so less that in NJ a gas attendant must pump your gasoline but diesel can be dispensed by the vehicle operator.

[Skyliner]

My wife's diesel Jeep's owner's manual actually states 5 minute idle cool down when towing. Most of the time it gets a minute cooldown in regular driving mode.

[MacGumbo]

Diesel has a high flash point and will not sustain flame easily. You can toss a lit match on a puddle of diesel and it will not ignite. Also even if you were to get some to light it may not sustain itself unless the amount of flame was large enough to vaporize surrounding fluid.

Several decades ago when teaching fire extinguisher classes we used to mix gas with diesel to get it to burn and it still did not light easily.

Leaving your diesel running is not a problem except in states where the law reads that a vehicle is not to be left running without a licensed driver inside.

[John McClain]

I would worry more about the gas fumes hitting the refrigerator pilot light than the truck idling.

[FFred]

In most states idling a diesel is illegal over 3 min, unless its near freezing.

While it is true the turbo may need a min or two, IF you have pulled a heavy load up Rocky Top mtn, there is no need for normal driving.

The problem with idling is the combustion pressure is very low.

The combustion pressure BEHIND the rings is what seals the piston and cylinder bore.

Excess blowby and oil dilution result from idling.

It burnishes the cylinder bore , removing the oil holding surface and can result in a slobbering engine, with high oil consumption.

"the refrigerator pilot light "

SHOULD BE OUT IN ANY GAS STATION!!!

[Cowracer]

I leave mine running. Usually for the A/C or heat. There is no safety issue, or at least is safer than somnambulant e-zombies paying more attention to their phones than the pump while fueling, or worse, the harried commuter who runs into the store while fueling, leaving a running gas pump unattended. I usually click them off if I see that.


Tim

[Cowracer]

Originally Posted by FFred

In most states idling a diesel is illegal over 3 min, unless its near freezing.

Name 'em. I have never, not once heard of such a thing. Maybe in California, but thats hardly 'most states'

Tim

[waiter21]

I rarely turn mine off while refueling. I have a saying, Never turn the engine off if you don't want to be break down and be stuck there.

With the engine running, its completely enclosed and presents no ignition source for any vapors. However, if I needed to start the engine, the second I engage the starter, it produces sparks that could ignite any fuel vapors.

[m35a2]

Originally Posted by FFred

In most states idling a diesel is illegal over 3 min, unless its near freezing.

While it is true the turbo may need a min or two, IF you have pulled a heavy load up Rocky Top mtn, there is no need for normal driving.

The problem with idling is the combustion pressure is very low.

The combustion pressure BEHIND the rings is what seals the piston and cylinder bore.

Excess blowby and oil dilution result from idling.

"the refrigerator pilot light "

SHOULD BE OUT IN ANY GAS STATION!!!

It burnishes the cylinder bore , removing the oil holding surface and can result in a slobbering engine, with high oil consumption.

Some good info here mixed with some bad.

For one thing, the exhaust temp at the turbo determines when it's safe to turn off. I can assure you that just driving at highway speed is enough to require idling before shutdown. 350 degrees is the generally accepted safe temperature. It's smart to monitor it, either with an odb2 or a physical gauge. Or just wait 5 minutes, which is enough time for the turbo to cool from max temp.

What states have laws limiting idle time to 3 minutes?

I always leave my truck running when fueling. Just like every rig in the 10 fuel lanes next to me when I'm pulling the camper.

[Mikegjax]

How about idling not being good for the "particulate filter"? I would think that "regeneration" to clean the particulate filter is much worse for the engine than restarting.

Normal driving to the pump after exiting the highway and getting to the fuel pump should be plenty of cool down time for the turbo. There could be exception to this, but not often. Additional cool down time can be added for exceptions.

If starter sparks were a concern I guess we would be blowing up service stations daily with all the gasoline powered vehicles that must turnoff their engines prior to fueling and then restart.

Just my two cents.