what happens if you run gas in a diesel engine?

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My son and I were discussing this, I didn't know exactly. I own a 02 VW bug with a diesel engine and he asked what would happen to the engine if you filled the tank with gas and drove it.

Could someone please help me answer his question?

Second question: which of the two fuels ignites easier in the engine and how does that play a role in what happens to the engine?

And a highly technical answer is fine, he's 17 and a budding genius about math/chemistry/computers...
 
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Lots of parts in a diesel setup rely on lubrication from diesel, that they won't get from gasoline. Short term it probably wouldn't do too much damage. Diesel has more energy density than gasoline, so it will lose power. And the gasoline may not detonate on compression effectively, so it may not run at all, depending on what percentage gasoline vs diesel is in the tank.
 
Knew a person who borrowed a friend's VW in college. He filled it up with 87 octane even though it says "Diesel ONLY" just about everywhere on the car.

The car wouldn't start, someone somewhere designed a safety for this sort of thing, and once he got to thinking about things... he knew he was in deep poo poo.
Thank goodness it wouldn't start as Diesel is more difficult to ignite because it is supposed to... well... diesel.
Due to the absence of spark plugs, and if the fuel injectors still worked correctly, eventually you would get 87 octane to diesel.
Depending on how it burned it might turn over the engine, then again it might burn in such a way to bend valves or cause other damaging high pressure spikes (perhaps blow a cylinder out the bottom like nitro methane, but who knows).
BTW, Diesel is Much more lubricant like than Gasoline, so there is that aspect of cylinder wear also.

Anyways, eventually they all got together and decided that the best course of action was to disconnect the main hose that lead to the fuel injection system and drained the entire tank in the parking lot of the gas station. I think it was like 15 gallons of gas going down the drain. Refilled with Diesel and it supposedly ran fine.

BTW, this was the same set of dudes that almost burned down an Apt. complex because they didn't have a lighter and decided to use a electric element on a stove to light a cigarette. They turned the stove top element on HIGH and then proceeded to pass out due to having too much to drink. A few hours passed, I stopped by, and felt radiant heat coming from the kitchen in the back, about 25 feet away. As I approached the stove top the element was a Bright cherry red, I had to wear gloves to get to the knob the stove top was so hot. Not bright fellows to say the least.
 
Yeah it's horrible for pumps and diesel don't run on octane but whats called cetane. The result will be horrible rattling and extreme lack of lubrication to the VERY expensive fuel system components

Diesel is harder to ignite and is ignited from compression rather then spark. Thus the very bad rattle from gas in a diesel will obviously occure.

Best advice pickup the green handle or for the shotty stations the yellow.....mobil
 
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I like the comment from "the straight dope" website

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What happens when you use gasoline in a diesel engine? Either something expensive or something very expensive.
 
Seems like the much higher compression of a diesel engine, combined with the higher volatility of gasoline, combined with the way direct injection of diesel engines works would cause a greater explosion in the cylinder, maybe at the wrong time (pre-ignition) and damage the engine catastrophically. Whew, long sentence.

Google diesel engine compression.
 
Originally Posted By: doitmyself
Seems like the much higher compression of a diesel engine, combined with the higher volatility of gasoline, combined with the way direct injection of diesel engines works would cause a greater explosion in the cylinder, maybe at the wrong time (pre-ignition) and damage the engine catastrophically. Whew, long sentence.

Google diesel engine compression.


This is correct, most pumps has octane ratings of 87-93. Diesel cetane runs between 47 and 55. 55 if your extremely lucky these days
 
High cylinder pressures and temps would pre-ignite.Plus injectors at what?... 1500-1800-or 2200 PSI would cause a flame thrower effect.Luckily,diesel engine components are so strong it wouldnt have an effect.As mentioned earlier it just wont run on straight gasoline.
 
Originally Posted By: gonzo
The nozzle from a diesel pump should not be able to fit into a gas powered vehicle.
I guess I should have payed more attention to what was being talked about.Just ignore what I said earlier.Thanks for not making me look too dumb.I don't need any help with that.
 
One of our less than stellar employees filled up the truck with Gas. An old Cummins ( 855 cubic inches ). Had to call the tow truck 5 miles down the road. Goodbye engine.
 
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The local BP station once accidentally put gasoline in my mother's 2004 BMW diesel. She drove it around for about 15 minutes with it stumbling badly and blowing heaps of white smoke. After she returned to the station they paid for the fuel to be drained out. It seems to still drive OK, 2 years later. The problem is if the high-pressure CR pump had been damaged a new one would have cost in the region of $6K in this part of the world.
 
My 1991 speced u could run up to 30% gas in a diesel in winter time. I never did.. causes detonation misfiring and eventually it will burn a hole in the piston valves totally destroy the engine most likely not to mention if it has any close fitting pump parts most likely they will seize up too.
 
Originally Posted By: DieselTech
Yeah it's horrible for pumps and diesel don't run on octane but whats called cetane. The result will be horrible rattling and extreme lack of lubrication to the VERY expensive fuel system components

Diesel is harder to ignite and is ignited from compression rather then spark. Thus the very bad rattle from gas in a diesel will obviously occure.

Best advice pickup the green handle or for the shotty stations the yellow.....mobil

The fuel charge in a diesel cylinder is ignited from the heat of compression, just like the fuel charge in a gasoline cylinder is ignited from the heat of the spark, or glowing red hot carbon, etc.

Neither a diesel runs on cetane or a gasoline engine runs on octane. Cetane is a measure of the time lag from the beginning of injection until ignition. A higher cetane number means a shorter time lag--good, less fuel accumulates in the cylinder before ignition and the fuel charge burns more smoothly. Octane is a measure of the knock resistance of the gasoline. Keep in mind one essential difference--in a diesel more fuel is injected while the combustion is taking place. In an Otto cycle (gasoline) engine the fuel charge is completely in the cylinder before combustion takes place.
 
military multi-fuel engines could run gasoline as a last resort per the manual. such as the m35a2. Tho it significantly shortens the life of the engine. Another practice if you had to run gas in your multifuel was to add a few gallons of waste or new motor oil to help in lubrication.

most owners of m35a2 have run on gas before just to try it because they can and usually add used oil to help lube.
 
It really depends on the engine and injection system design.

There are many Aussies who have accidentally filled up on petrol, and had little issue rather than not running right. Others have had to ante up for new injection equipment that's failed due primarily to inadequate lubrication.

A workmate's father drove his Nissan some 600km on 50:50 RUG and diesel, realising his mistake as he read the receipt on the way back to the car, but driving it anyway. Vehicle has a c9omputer controlled axial pump, which is known to be finicky, but seems not to have suffered. Shoudl have thrown in a litre of oil IMO once they knew their error.
 
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