To run, or not?

[CDyksman]

Can anyone tell me why it's ok to leave a diesel running when fueling, and not when filling a gasser? Many thanks.

 

[1965LONEWOLF]

i do it all the time - no problem

 

[CDyksman]

I do it all the time too. My question is what is the difference that makes it ok to do in a diesel, and not a gasser?

 

[JGheen]

Compression ignition vs. Spark ignition.



Joe

 

[CDyksman]

Compression ignition vs. Spark ignition.



Joe

That is what I thought. Thanks

 

[Dieselnerd]

Gasoline fumes are explosive and can be ignited with a cigarette or even a spark of static electricity. Diesel fumes are not explosive at normal air temperature.



Throw a lit match in a bowl of gasoline and you have an instant fire, throw that same match in a bowl of diesel fuel and it will go out. So, it is not nearly as dangerous to leave your motor running when pumping diesel. Spill diesel on hot engine parts and it will burn pretty good too so don't get so comfortable you get careless.

 

[LesStallings]

A lot of folks, after a hard run (pulling heavy loads or hotrodding) like to keep the truck running to keep oil flowing to the turbo bearings. It is the same principal as a cool down timer.



The big trucks always refuel with the engine running.

 

[HOBrian]

Plus some new cars if left running with the fuel cap off will set off the check engine light.

 

[CDyksman]

Dieselnerd,, thanks for the info. I was looking for some reasonable info. As compression ignition VS spark ignition didnt quite make sense, as both processes still make the fuel burn. . Thanks again.

 

[DFrank]

If one idles with a diesel near others filling with gasoline, does that cause any risk factors?

 

[MacHaggis]

What they said, with a twist. Our trucks don't have coils and condensers going, but there can still be some static generated. And you can genreate your own static that could generate a spark. But you're still not going to ignite a tank of diesel with that spark.



That said, I've been told it may be a good idea to shut down if you have to fuel from a pump that has both diesel and gas hoses. Seems to me the danger is from a spark at the top of a filler neck on a gasser. Hard to imagine that a spark on a filler neck would set of another hose five feet away. But I'm not gonna test it, either.

 

[betterthanstock]

If one idles with a diesel near others filling with gasoline, does that cause any risk factors?

Sure. Our diesels (except for some older cars and the new 07's) do not have throttle valves. So any gasoline vapors, or propane/natural gas in the air will make our diesels accelerate. Usually, if you can smell gas or propane, the engine will slightly accelerate, but sometimes it's not too obvious because the computer will cut off some or all diesel fuel if it spins too fast. Turning off the ignition key will stop the injectors, but if there are ENOUGH gasoline or propane vapors, they will continue to accelerate until they blow up around 6000 rpm.



The only way to stop it, IF you have time, is to put it in gear with the brakes on, (very dangerous if it's spinning fast), or to use the exhaust brake, or to spray fire extinguisher or water at the air filter.

Several people have died along the years trying to stop a runaway diesel.



If you notice sudden acceleration while approaching a gas or propane station, the best thing is to drive away if you can, if not, turn off ignition and keep in gear/slip the clutch with the brakes on until you stall the engine, even if you are burning rubber. Usually it does not have that much power. Taking it out of gear may immediately blow it up. If you are already outside, run to the rear of the truck so any flying engine parts will not hit you.



Also, if there are enough vapors to make a diesel run away, there is also the risk of an explosion, so drive away if you can.



Fueling tankers always shut off their engines, and they even have a throttle valve designed to close if the engine overspeeds.



I once glued something with "liquid nails" around my air filter, and it accelerated when I started the engine to about 12-1500 rpm, for about one second just on the fumes. It had a nasty, knocking sound, and oh yeah, it scared me.



see here

http://www.mckenziecorp.com/air_intake_valve.htm

 

[Hoefler]

One more thing, the catalytic converter on gassers get extremely hot. It will set off gasoline vapor if it gets concentrated enough. Things may start changing with the diesels having convertors now.

 

[MChildress]

This will make a few scratch their head. We would run diesel exhaust into used steel gas tanks before welding on them. This would dry the tanks out and push the gas fumes out. This was about twenty years ago but never had a problem. I cut a propane tank the other day and went the water fill method,a lot smaller explosion.