Home » General » What Happens If You Put Diesel In A Gas Car? | (Full Answer)

What Happens If You Put Diesel In A Gas Car? | (Full Answer)

When you pull up to the fuel pump, you will likely notice several nozzles with different types of fuel. Gasoline is available in different octane ratings, non-ethanol gasoline may be present, and some pumps also have diesel fuel available. You might think that fuel is fuel, but that is certainly not true! Diesel fuel can have severe adverse consequences on your gas vehicle, and you will be stuck with a hefty repair bill if you accidentally put diesel fuel in your gas car. Keep reading as we tell you exactly what happens in this situation, how to handle it properly, and how you can prevent it.

What Happens If You Put Diesel Fuel In A Gas Car?

You probably wonder what happens when you put diesel in a gas engine. The answer is that many bad things can potentially occur, especially if you attempt to start your car. Diesel fuel is much thicker than gasoline, and diesel engines are made specifically to accommodate this fact. The combustion properties are also much different, so your gas engine will not run properly with diesel fuel. Here is more detailed information on the problems you can expect if you put diesel fuel in your gasoline engine.

— Damage To Fuel Pump

Your fuel pump is critical to the fuel system as it pulls gasoline from the fuel tank and pumps it to the fuel injectors. The injectors spray the fuel into the combustion chamber of the engine. Since diesel fuel is so much thicker than gasoline, the fuel pump will struggle to pump the fuel out of the tank and through the fuel lines.

The pump will work much harder than normal, putting a severe strain on the electric motor of the pump. You will start to see the symptoms of a bad fuel pump right away. Your fuel pump will quickly become overworked, and it may also overheat. Damage to the pump will occur, and you will likely have to replace the fuel pump due to this issue. Diesel pumps on diesel vehicles are designed specifically to handle thicker fluid, but gasoline pumps cannot perform under the strain.

— Clogged Fuel Filter

Not only will thicker fuel wreak havoc on your fuel pump, but your fuel filter will have problems too. The filter is designed to remove small particulates from gasoline, and thicker diesel fuel will have trouble flowing through a fuel filter designed for gasoline. This will clog your fuel filter and prevent fuel from flowing through the system at all. Once the filter becomes clogged and gummed up from diesel fuel, a replacement will be necessary.

— Clogged Fuel Injectors

The fuel injectors in your gasoline engine spray a fine mist of gasoline into the engine’s combustion chamber. The spark plugs create a spark and ignite the gasoline mixture in the chamber. Diesel fuel will completely destroy gasoline fuel injectors. Since diesel fuel is so thick, the injectors will almost immediately become clogged. Your injectors will be ruined, and thorough cleaning will be necessary. In some cases, replacement might even be required.

What To Do If You Put Diesel In Your Gas Engine

The best gas stations make it almost impossible to accidentally put diesel fuel in your gasoline car. The diesel nozzle is usually a bright green color, and the size of the nozzle is designed so that it will not fit into the filler neck of your fuel tank. However, accidents still happen. So, what should you do if you accidentally put diesel fuel in your car? Here are the steps you should take.

1. Do NOT Start The Car

This may be the absolute most important thing to remember if you accidentally put the wrong fuel in your car. Do NOT start the vehicle under any circumstances, as this will result in immediate engine damage. If you start the vehicle, the fuel pump will attempt to pump the diesel out of the gasoline tank. The diesel will clog the fuel filter and fuel injectors and gum up the entire fuel system. Even a small amount of diesel entering the fuel system can ruin your car’s engine. As long as you keep the diesel contained in the gas tank, the repair is not as complex or expensive.

2. Call A Tow Truck

As soon as you discover the fact that you accidentally put diesel fuel in your car, you should call a tow truck. As mentioned above, you should not start the car — even for a few seconds. Call a tow truck to move the vehicle away from the gas pump to a repair shop. Even when you don’t start the car, the repair will require quite a bit of work. The fuel tank will need to be cleaned, so you will need to get the car to a shop.

3. Have A Mechanic Drain The Fuel Tank

Once your car arrives at the repair shop, a mechanic will need to drain the fuel tank and clean it thoroughly. Even a few gallons of diesel in your gasoline tank can cause huge problems. Draining the tank of all the diesel is an absolute requirement before attempting to start the car. If you completely fill the tank with diesel, the tank might also need cleaning. Once the tank has been drained and cleaned, it can be refilled with gasoline, and the vehicle can be started.

Differences Between Diesel Fuel And Gasoline

Now that you know you can only put gasoline in your gas engine, you might be wondering why the type of fuel makes such a big difference. When you start to examine the differences between gasoline and diesel, you will quickly see the reason. The first difference between diesel and gas is the thickness or density. Gasoline is more refined than diesel fuel; therefore, it is thinner. Since diesel fuel is denser than gas, it also contains more energy when combusted than the same volume of gasoline.

Diesel engines take advantage of the unique characteristics of diesel fuel. These engines use glow plugs to raise the temperature inside the cylinders, whereas gasoline engines use spark plugs to generate a spark inside the combustion chamber. Diesel fuel ignites inside the engine using compression, but gasoline engines use a spark to ignite the fuel. You already know that putting diesel in your gas engine will cause problems, but damage can also occur if you put gasoline in your diesel tank. Gasoline and its additives can result in premature ignition, which is likely to result in serious engine damage.

Diesel engines usually last much longer than gasoline engines. Diesels typically have larger cylinders, pistons, and other engine components. This extra space allows the oil to provide better lubrication to the engine components. It is not uncommon for a diesel engine to exceed 300,000 miles, while this would be a rarity for a gasoline engine.

Cost To Flush Diesel Fuel Out Of Your Car

Draining your gas tank of diesel fuel that has been accidentally put in there will usually cost you anywhere from $300 to $600. As long as you have not attempted to start the vehicle, a professional mechanic can complete this repair in a couple of hours. However, if you have attempted to start the car, the repair bill will increase significantly.

Once the diesel fuel has entered the fuel system, a complete fuel system flush and cleaning will be required. The bill for that task is likely to cost you $1,200 or more, and some parts might also need to be replaced. You will need a new fuel filter, and you might even have to replace the fuel pump or fuel injectors. Repair costs can quickly rise above $2,000 if you need to replace these parts.

Tips For Getting The Right Fuel For Your Engine

So, how can you avoid a mix-up and always put the right type of fuel in your vehicle? First, the type of fuel required for your vehicle is usually displayed on a small sticker inside the fuel door. Most passenger vehicles require unleaded gasoline, and some require premium gasoline. Make sure that you double-check the nozzle when putting fuel in your car. Bright green covers on the nozzle usually signify a diesel pump, and those nozzles are generally larger than gasoline nozzles.

If you have trouble getting the nozzle to go into your fuel tank’s filler neck, stop! Make sure you are using the proper type of fuel, and ask for help if necessary. Getting help from a stranger might seem embarrassing, but it could save you several thousand dollars in repair costs if you accidentally put diesel fuel in your car!

The Bottom Line

Putting diesel fuel in your gas car will result in far worse damage than a misfiring engine. The fuel system will need to be completely flushed and cleaned, parts will likely need to be replaced, and severe engine damage might occur. If you accidentally put diesel in your car, you should NOT start the vehicle. As long as you do not attempt to start the car, you can have a mechanic drain the fuel tank and refill it with gasoline. By performing that procedure, you should save yourself from any serious damage to your vehicle.

Frequently Asked Questions

Will a small amount of diesel hurt a gas engine?

Yes, even a small amount of diesel fuel can harm a gas engine. Diesel fuel is much thicker than gasoline. The thickness resembles lightweight engine oil. Even a few gallons of diesel in your gas tank can damage your fuel pump, fuel injectors, fuel filter, and other fuel system components. In addition, damage to the engine may occur due to the nature of diesel’s combustive properties. The best advice for anyone who puts diesel in their gas tank is to immediately get the help of a mechanic who can drain the fuel tank and remove all the diesel fuel.

How long can a gas engine run on diesel?

Can you put diesel in a gas car for just a small period of time? No! A gas engine cannot run on diesel at all. If you put diesel in your tank, your car might start and run for a few seconds. However, it is running on the gasoline that is still contained in the fuel lines. As soon as the fuel pump attempts to pump the diesel fuel into the engine, you will have problems. You will likely see black smoke initially; then, the car will shut off. At this point, the damage has been done, and your repair bill is likely to exceed $2,000.

Can I put gasoline in a diesel engine?

No, you cannot put gasoline in a diesel engine. If you do, you could cause catastrophic damage to your diesel engine. You would need to get your vehicle to an automotive repair shop to drain the diesel tank of all gasoline. Gasoline is much more combustible than diesel fuel, so the engine may have premature ignition. This could cause major damage to the internal engine components.

Leave a Comment