This post has already been read 2714 times!
Last year in Britain more than 150 000 drivers put diesel fuel into the tanks of petrol-engined cars, or petrol into the tanks of diesel-engined cars.
By Jake Venter on ToyotaZone
In SA we also sometimes make these mistakes, but the numbers are significantly lower. We employ pump attendants that usually know what to do, but in Britain motorists perform this task themselves, and many of them are often dozy or inattentive.
In both cases the best advice is to not turn on the ignition because many modern engines have electric pumps that go into action as soon as the ignition is switched on. Obviously, this also means that one should never start the engine.
Petrol in a diesel tank
Modern diesel fuel injection equipment operates at very fine clearances and pressures between 500 and 2 000 bar. (Your tyres take about 2 bar; one bar = 100 kPa). The slightly oily diesel fuel acts as a lubricant for the pump internals as well as the injector nozzles, but petrol acts like a solvent. It will wash any oiliness away and cause the metal-to-metal contact. The resulting metal particles will be carried by the fuel to other parts of the engine where they will cause further damage.
Some of the additives in the fuel may also affect seals and other non-metal parts. Most modern diesel cars are fitted with common-rail diesel engines and these are particularly vulnerable because of the number of expensive hi-tech components.
If you get petrol in the tank and the fuel pump has not been activated then all one has to do is clean all the contaminated fuel out of the tank, but if the pump has sent fuel though then your actions would depend on how long it has been pumping. A few seconds may not make much difference, but every component that could have been affected should be inspected. In some cases this may mean that it would be cheaper to install a new engine!
Diesel fuel in a petrol tank
This is may not be quite so serious, depending on how old the car is. Older cars with carburetors will most likely be difficult to start, and run badly. You would get by with just a fuel system cleanout. I know, because I’ve done it.
The fuel injection equipment on modern cars could be damaged by the additives in the diesel, especially if the engine is fitted with direct fuel injection into the combustion chambers.
Additional filling-up advice
Most South African pump attendants are instructed to wait for the automatic pump stop to take effect, and then trickle in some more fuel. This is done to sell more fuel, but is not a good idea.
Fuel tanks are designed with about a 15 per cent air space above the fuel for two reasons. It eliminates wastage due to fuel expansion on a hot day, and it reduces the risk of a tank bursting as the result of an accident. Some people make use of this extra space to carry more fuel, but the correct thing to do is to ask the pump attendant to remove the fuel hose as soon as the automatic stop has been activated.