If you’ve accidentally put gasoline in your diesel engine, you may be panicking a little bit (or a lot) over what to do now. First things first, if this has happened to you, you should not turn your car on or drive it – this will only make the problem worse. Jump down to our section on what to do if your diesel engine has gasoline in it below for immediate help.

It is important to note that putting gasoline in a diesel engine does have some serious consequences that may result in severe engine damage if not treated in time. Our article will help you to understand why gasoline should not ever be placed into a diesel engine, some of the symptoms that you will experience if gasoline and diesel mix, and what to do if your diesel engine, unfortunately, comes into contact with regular gasoline.

Why Does Gasoline Not Work in a Diesel Engine?

Because gasoline engines and diesel engines work in very different ways, mixing fuel between these two will only result in problems. Gasoline engines work using spark plugs – gasoline fuel ignites the spark plug in the combustion chamber, powering your vehicle. Diesel engines, on the other hand, rely on high amounts of air pressure that diesel fuel is carefully injected into at the right time.

Once you accidentally place gasoline – even a small amount – into a diesel engine, it changes the flashpoint of the diesel fuel. This means that the diesel fuel will prematurely ignite in the engine, leading to damage.

Gasoline in your diesel engine may also damage the fuel pump and cause issues with the diesel injectors, as gasoline is a solvent and diesel is more of an oil. Taking away some of the lubrication that diesel fuel gives the engine will only result in engine damage.

Symptoms of Gasoline in a Diesel Engine

These symptoms may occur when gasoline is placed into a diesel engine. If you are not sure whether or not you have mixed up your fuel types, you can keep an eye out for these symptoms to narrow down the possibility.

This said, if you are experiencing one or more of these symptoms and suspect that gasoline has been put into your diesel engine, you should stop driving your car immediately and get to the closest mechanic’s shop for a proper evaluation and assistance.

No Ignition

Gasoline needs a spark plug to ignite and diesel engines are not specifically designed to ignite fuel. No ignition when you try to start your car could indicate that there is a serious amount of gas in your diesel engine. If there is an ignition despite a mix of diesel and gasoline, it will likely be too much for your car to handle and will cause serious engine damage.

No Engine Lubrication

Diesel fuel is designed to act much like an oil and lubricate the engine’s components as it powers the vehicle. Gasoline is a solvent and not designed for this purpose, so putting gasoline into a diesel engine will leave the engine without lubrication. As parts of the engine rub against each other, damage will occur.

Black Smoke

The flashpoints between gasoline and diesel fuel are very different – the lower a flashpoint, the easier it is to ignite the fuel. Because of the differences in flashpoints, it can be much harder for a diesel engine to ignite gasoline. This means that there will be a lot of unburned fuel, which will translate to black smoke coming out of the exhaust of your vehicle.

Black smoke may also clog up various parts of your car’s operating system, causing issues for the entire fuel system.

Fuel System Damage

Diesel engines are not designed to utilize gasoline; when gasoline enters into the fuel system, it will affect the fuel pump, fuel injectors, and fuel filter. These components can start to fail individually but eventually can lead to severe damage and failure of your car’s entire fuel system.

Engine Damage

Because adding gasoline into a diesel engine can affect every small part of the fuel system and engine, it is common for the entire engine to sustain damage. Gasoline can also cause a detonation in your vehicle’s engine that may damage its pistons, rods, and wrist pins.

The longer you allow your vehicle to operate with gasoline, the more likely it is that your entire engine will become damaged to the point that it needs to be completely replaced.

As your engine starts breaking down, you may experience a lack of power when accelerating, strange noises, or rough idling.

What to Do if Your Diesel Engine Has Gasoline in It

If you’ve realized a little too late that you accidentally put gasoline in your diesel engine, there are a few next steps to take to ensure that you minimize damage to your engine.

• Do not start your car’s engine or try to engage the ignition. If you have already started it before realizing the mistake, then pull over your car as soon as it is safe to and turn off the engine.
• Stay near your turned off car and call for a tow truck to pick you up. Have the tow truck take your vehicle to the nearest mechanic’s shop.
• Once you are speaking with a mechanic, tell them your mistake and allow them to get to work fixing it. Your fuel system will need to be drained and completely flushed out to rid your car of any trace of gasoline.

As long as you did not turn on your diesel engine after placing gasoline in it, the damage can be relatively contained. The moment that you turn your ignition to the ‘on” position or start to drive your vehicle with gasoline in the diesel tank, you begin running the risk for serious engine damage.

Repair Costs for Gasoline in a Diesel Engine

Depending on how long you have been operating your vehicle with gasoline in the engine, you may need to pay some significant repair costs. If you have been driving your vehicle for an extended period of time with gasoline in it, you run a greater risk of damaging the entire engine, which can lead to a costly replacement.

On average, a complete fuel system flush out could cost between $80 and $120 depending on your vehicle type and the labor involved. If your engine has been running for a little bit with gasoline in it, you may be looking at costs between $100 and $500 (including parts and labor) to replace various system components.

For a very severely damaged engine, you could be looking at costs of between $1,000 and $4,000 or more depending on if the engine needs to be completely replaced and if there are any ongoing replacement issues necessary.

Keep in mind that visiting a local mechanic will be a much more costly option than taking your car to be serviced at a dealership.

Keep Your Diesel Engine Running

Accidentally putting gasoline in your diesel engine can be a serious issue, but it doesn’t need to be the end of the world as long as you catch the problem in time. The best way to deal with gasoline in your diesel engine is to shut your car off (or keep it turned off) and get it towed to the nearest mechanic’s shop for a fuel system flush out. From there, be sure to pay extra attention when gassing up your car in order to keep your diesel engine running smoothly.