The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 10-09-2003, 08:01 PM
Wesley Clark Wesley Clark is offline
Guest
 
Join Date: Aug 2003
what if i accidentally put diesel into my cars gas tank.

the diesel pump is always right next to the regular gas nozzle. what if by accident i put diesel into my cars gas tank, would it permanently ruin it, would the car run badly for a while but no damage, or what?

its my understanding diesel doesn't require a spark and i think it explodes due to pressure instead of a spark so i dont know if it would blow up earlier or later in the piston cycle than regular gas would. If later you'd assume no damage as the spark would ignite it, if before then the piston cycle would be ruined.

So what damage would it do.
Reply With Quote
Advertisements  
  #2  
Old 10-09-2003, 08:07 PM
Q.E.D. Q.E.D. is offline
Charter Member
 
Join Date: Jan 2003
Location: Richmond, VA
Posts: 22,536
I think the diesel nozzle is too large to fit into the filler neck on a standard gasoline-burning car, but I'm not sure. I know back when there was still leaded gas at the time unleaded was beginning to be popular, the nozzles for leaded gas wouldn't fit into cars that needed unleaded.
__________________
SnUgGLypuPpY -- TakE BaCk tHe PiT!
Reply With Quote
  #3  
Old 10-09-2003, 08:09 PM
bojon bojon is offline
BANNED
 
Join Date: Sep 2003
Location: colorado
Posts: 231
Depends how much you put in. If a little, you will smoke like a broken piston. if a lot, drain it out. If easily embarrassed, drain it out.
Reply With Quote
  #4  
Old 10-09-2003, 08:42 PM
Conflict of Interest Conflict of Interest is offline
Guest
 
Join Date: Mar 2003
QED is correct in that the nozzle for diesel is larger and will not fit into the neck of your gas tank.
Reply With Quote
  #5  
Old 10-09-2003, 09:05 PM
Nuke Nuke is offline
Guest
 
Join Date: Dec 2002
If by accident you put diesel in a gasoline powered car, the engine won't run. Don't ask how I know .......



(made a big mistake in Europe with a rental car).
Reply With Quote
  #6  
Old 10-09-2003, 09:09 PM
Q.E.D. Q.E.D. is offline
Charter Member
 
Join Date: Jan 2003
Location: Richmond, VA
Posts: 22,536
Quote:
Originally posted by Conflict of Interest
QED is correct in that the nozzle for diesel is larger and will not fit into the neck of your gas tank.
Ah, thank you. I wasn't positive, as I haven't yet managed to be oblivious enough have done this. Apparently this isn't the case in Europe... *snickers at Nuke*
Reply With Quote
  #7  
Old 10-09-2003, 09:11 PM
asterion asterion is offline
2012 SDMB NFL Salary Cap Champ
Charter Member
 
Join Date: Jul 2002
Location: Guilderland, NY
Posts: 10,138
One time when I was working at a gas station, I had a guy come in with an old van who was having some sort of engine problem. The mechanic he had gone to actually suggested putting a little diesel in it; couple of gallons if I remember correctly. Does anyone know why this would work and for what?
Reply With Quote
  #8  
Old 10-09-2003, 09:17 PM
Gorsnak Gorsnak is offline
Charter Member
 
Join Date: Jan 2003
Location: Saskaboom
Posts: 8,036
Quote:
Originally posted by asterion
One time when I was working at a gas station, I had a guy come in with an old van who was having some sort of engine problem. The mechanic he had gone to actually suggested putting a little diesel in it; couple of gallons if I remember correctly. Does anyone know why this would work and for what?
A little diesel mixed into a tank of gas might cure a sticky valve. Diesel is a decent lubricant/penetrating oil. If memory serves, my father's used this trick on an old recalcitrant swather engine.
Reply With Quote
  #9  
Old 10-09-2003, 09:22 PM
Nuke Nuke is offline
Guest
 
Join Date: Dec 2002
Quote:
Originally posted by Q.E.D.
Ah, thank you. I wasn't positive, as I haven't yet managed to be oblivious enough have done this. Apparently this isn't the case in Europe... *snickers at Nuke*
Well, it definitely was not the case in Slovakia in 1996. The engine in that Volkswagen wagon I rented rattled so much I just assumed it was a diesel. After refueling from 1/4 tank, I got about a mile down the road before the diesel fuel hit the engine. Lots of smoke and then no go. I had to siphon the tank (gave the fuel to the guy who stopped to help me - nice people in Slovakia BTW) and refill with gas to get going again.

The car didn't seem to suffer any ill effects and I neglected to mention this escapade when I returned the car. I think if you did this to a modern American car, you'd plug up the catalytic converter real fast.
Reply With Quote
  #10  
Old 10-09-2003, 11:13 PM
starfish starfish is offline
Guest
 
Join Date: Oct 1999
In the 70's before the no-lead gasoline, the diesel nozzle would fit in the fuel tank.

I accidently put a few gallons of diesel in the tank. The mechanic at the gas station said not to worry about it, just fill the rest of the tank with gasoline. He was right; I never noticed any effect.
Reply With Quote
  #11  
Old 10-10-2003, 12:12 AM
5cents 5cents is offline
Guest
 
Join Date: Aug 2003
Re: what if i accidentally put diesel into my cars gas tank.

Quote:
Originally posted by Wesley Clark
the diesel pump is always right next to the regular gas nozzle. what if by accident i put diesel into my cars gas tank, would it permanently ruin it, would the car run badly for a while but no damage, or what?

its my understanding diesel doesn't require a spark and i think it explodes due to pressure instead of a spark so i dont know if it would blow up earlier or later in the piston cycle than regular gas would. If later you'd assume no damage as the spark would ignite it, if before then the piston cycle would be ruined.

So what damage would it do.
Either the car won't run or it will be smoking like a fiend, Depends on the ratio of gasoline to diesel in the tank. If it won't run, drain the tank and fill it with gas, and all should be fine.

Going the other way around (gasoline in a diesel) will work, but you'll get reduced power, and some parts of the fuel system (injection pumps, seals, etc) might not be too happy, depending on their design. There are a number of multi-fuel designs that are slightly modified diesel engines that can take just about anything you've got (diesel, gasoline, av gas, etc). Very useful for a military vehicle.
Reply With Quote
  #12  
Old 10-10-2003, 12:51 AM
SlickRoenick SlickRoenick is offline
Guest
 
Join Date: Mar 2002
One time at Ace Hardware this idiot (Jim) put diesel into the forklift which runs on gasoline. After he blamed me i decided to make it worse for him and purposely act ignorant. So i drove the forklift for about 2 hours moving stuff in and out and around the warehouse. It performed terribly. Slow to accelerate, really had to give it throttle to pick up a pallet of anything. When i was done, the lot looked a forest fire that was just extinguished.

p.s. the motor was rebuilt shortly after that.
Reply With Quote
  #13  
Old 10-10-2003, 01:38 AM
Zenster Zenster is offline
BANNED
 
Join Date: Jun 2000
Location: Silicon Valley
Posts: 9,515
what if i accidentally put diesel into my cars gas tank.

You would have one or more nonfunctional vehicles, depending upon where the apostrophe was correctly placed in your thread's subject line.
Reply With Quote
  #14  
Old 10-10-2003, 01:45 AM
Fuji Kitakyusho Fuji Kitakyusho is offline
Guest
 
Join Date: Jan 2003
Re: Re: what if i accidentally put diesel into my cars gas tank.

Quote:
Originally posted by 5cents
Either the car won't run or it will be smoking like a fiend, Depends on the ratio of gasoline to diesel in the tank. If it won't run, drain the tank and fill it with gas, and all should be fine.

Going the other way around (gasoline in a diesel) will work, but you'll get reduced power, and some parts of the fuel system (injection pumps, seals, etc) might not be too happy, depending on their design. There are a number of multi-fuel designs that are slightly modified diesel engines that can take just about anything you've got (diesel, gasoline, av gas, etc). Very useful for a military vehicle.
I don't get that. Diesel engines do not use spark plugs, relying instead only on the compression of the cylinder and volatility of the fuel to self-ignite. Logically then, it would seem that gasoline wouldn't work in a diesel, but that diesel might work in a gasoline engine, albeit with strange effects.
Reply With Quote
  #15  
Old 10-10-2003, 01:47 AM
Trom Trom is offline
Guest
 
Join Date: Apr 2002
I worked summers at a golf course on the groundscrew. My boss grew up on a farm, farmed all his adult years, then later got into golf courses. The guy has been around engines all his life. Some of our machines were diesel, others were gas. On the first day he -emphasized- not putting gas in the diesel engines. He said it would be ok if we put diesel in the gas engines, but they would just miss a lot and not run well.

I've never had any experience with mixing up, but I clearly remember his warning.
Reply With Quote
  #16  
Old 10-10-2003, 02:17 AM
Jeff Lichtman Jeff Lichtman is offline
Head Cheese
Charter Member
 
Join Date: Feb 2000
Location: El Cerrito, CA
Posts: 2,732
Re: Re: Re: what if i accidentally put diesel into my cars gas tank.

Quote:
Originally posted by Fuji Kitakyusho
I don't get that. Diesel engines do not use spark plugs, relying instead only on the compression of the cylinder and volatility of the fuel to self-ignite. Logically then, it would seem that gasoline wouldn't work in a diesel, but that diesel might work in a gasoline engine, albeit with strange effects.
Diesel fuel is similar to kerosene. Diesel fuel is more viscous, less volatile and less flammable than gasoline.

A diesel engine uses compression to heat the air in the cylinder. It then uses fuel injectors to spray fuel into the cylinder as the piston goes down. Because the temperature due to compression is high enough to ignite the fuel, no spark plug is needed. The injectors don't spray the fuel in all at once - they continue to put fuel into the cylinder as the piston descends. Ideally, a diesel engine has constant pressure in the cylinder during the power stroke.

A gasoline engine (technically, an Otto cycle engine) relies on a spark plug (or similar device) to ignite the fuel/air mixture near top dead center. The fuel burns rapidly, while the piston is near top dead center. The fuel must be both very volatile and flammable for a spark to ignite it under these conditions. Also, the fuel must burn rapidly for it to be consumed while the piston is near top dead center.

If you put diesel fuel in a gasoline engine, the carburetor or fuel injectors will have a hard time due to diesel's relatively high viscosity and low volatility. The spark plugs probably won't ignite whatever fuel does make it to the cylinder.

I don't know what will happen if you put gasoline in a diesel engine. My guess is that the engine will run, but will break quickly. Diesel engines may rely on the fuel for lubrication, and diesel is a much better lubricant than gasoline. Also, it's possible that too much gasoline would get into the cylinders (due to gasoline's low viscosity), causing the engine to run hot and putting too much force on the bearings.
Reply With Quote
  #17  
Old 10-10-2003, 02:28 AM
flodnak flodnak is offline
Member
 
Join Date: Aug 1999
Location: outside Oslo, Norway
Posts: 4,763
Quote:
Originally posted by Q.E.D.
I think the diesel nozzle is too large to fit into the filler neck on a standard gasoline-burning car, but I'm not sure.
The world is a very big place. Here in Norge, where diesel cars are relatively common, the nozzles sure seem to be exactly the same. However, most gas stations put a honkin' big DIESEL sign on the handle to prevent mix-ups. Also, they're color-coded: a green nozzle is for unleaded, red is for leaded, and diesel nozzles are either black with yellow lettering or yellow with black.

Never put diesel in my tank by mistake (our cars are both gasoline powered), but the few folks I know who have managed this say the biggest damage is to one's pride. Of all the stoopid things to cause a breakdown...
__________________
An American flodnak in Oslo.
Do not open cover; no user serviceable parts inside.
Reply With Quote
  #18  
Old 10-10-2003, 06:46 AM
rodmunch rodmunch is offline
Guest
 
Join Date: Jul 2003
i made the mistake of putting some in my vw beetle. i had had a bad day at work and on the way home i had to get some petrol. i only had 2 on me (luckily) so put 2 (about 3 litres) in the almost empty tank. i even remember seeing 'diesel' appear on the screen as i was paying for it but didnt twig. i drove off down the road and noticed that it kept misfiring (which i didnt take much notice of as this happened more than often) then it started happening more and i looked in my rear view mirror and i couldnt see for smoke behind me. then the car stopped on the outside lane on the approach to a busy round-a-bout and i was engulfed in smoke (that is no exageration i got out and couldnt see my hand in front of my face until the smoke cleared). i called the AA out and they said that as id only put a bit in i should be ok if i fill up the rest of the tank with 4*. so he towed me back to the petrol station and i filled up. it seemed to work but was misfiring a hell of a lot for a few weeks after that until it was all out of the system. a couple of months after that i had to get a new engine (not sure if it was related to the diesel incident though)
Reply With Quote
  #19  
Old 10-10-2003, 07:36 AM
Edward The Head Edward The Head is offline
Charter Member
 
Join Date: Jun 2000
Location: Somewhere in time
Posts: 5,795
I've seen this happen with motorcycles since the filler hole is much bigger then a car's is. Usually it will back fire, throw some cool looking fire and then stop. Since a bike's tank is a lot smaller then any car I know you can not just dump out the diesel and put in real gas, you usually have to change the plugs because they become foul and sometimes clean the carbs.

For the most part in the states diesel is on the green pump, but sometimes the regular gas is on the green pumps. I'm always worried that I'll put diesel into one of my bikes so I always read it.
Reply With Quote
  #20  
Old 10-10-2003, 09:41 AM
Tamex Tamex is offline
Guest
 
Join Date: Jul 2000
My dad accidentally put diesel fuel in his Pinto once when we were on a road trip when I was a kid. We noticed right away when the car started emitting thick, black smoke. We spent a few hours in this podunk Wyoming town at the garage having the gas tank drained.

Dad doesn't like us to bring that incident up. I'm only mentioning it in order to combat ignorance.
Reply With Quote
  #21  
Old 10-10-2003, 01:55 PM
Scumpup Scumpup is offline
Guest
 
Join Date: Mar 2003
Accidentally filled a two-stroke motorcycle tank with diesel, once. Ended up with a mixture that was about 1/3 gas and 2/3 diesel. It was difficult to get it started, but once started it did run. Left quite a smoke trail too.
Reply With Quote
Reply



Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 08:18 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright 2013 Sun-Times Media, LLC.