The warning comes from leading aftermarket specialists, Feather Diesel Services who are reminding motorists that diesel fuel injection systems are lubricated by the fuel and, in some cases, common rail injectors have just 1 micron (1,000 microns equal 1mm) clearance between moving parts – meaning minimal margin for error.
Historically, sulphur acted as the natural lubricant but the environmental impact of irritant sulphur oxides in exhaust gas emissions, which include causing or worsening respiratory problems, led to the mandatory adoption of Ultra-Low-Sulphur-Diesel (ULSD) in the UK since 2006.
Before this, fuel injection system manufacturers had already voiced concerns in a joint statement to legislators after seeing rising premature failures of diesel fuel injection equipment due to lack of lubrication with the new ULSD fuels.
Fuel injection system designs were adapted to meet the demands of new fuel chemistry and fuel companies developed alternative chemical lubricants into their refining processes.
A further challenge has since been presented by the rise in biofuels. These generally now make up at least 5% by volume of diesel fuel, and are set to rise to 10% by 2020, under the EU Renewable Energy Directive.
Since 2003, the quality of biofuels to be introduced has been controlled by British Standard BS EN 1424, and diesel under BS EN 590.
BS EN 590 specifies cetane rating ranges – relating to the speed of combustion – but has some loose limits, creating potential for variable quality fuels to be sold.
Steve Smith, Feather Diesel’s Managing Director, said: “Biofuel is more unstable and tends to degrade progressively.
“Oxidisation creates formic and acetic acids, which attacks the fuel injection equipment.”
Products used in the refining of bio diesel, which can’t be fully removed, remain as ‘tramp’ chemicals and can cause potassium, sodium and water to become present too.
“Biofuels attract free water more readily than pure diesel, which is also naturally hygroscopic” explains Steve.
“This increases corrosion of the injection equipment and can block filters. Biofuels also attack elastomers more readily, including nitrile seals.”
Feather Diesel say biofuel content can lead to numerous diesel fuel injection problems, including leaks, overheating components, sticking injectors and pumps, solidification or waxing in winter and component erosion from higher levels of impurities.
With no test to check stability of bio fuel, there are no ‘use by’ dates; storage conditions, temperature and environment will all affect the speed of oxidisation.
Premium brand fuel
Feather Diesel say premium brands of fuels have vital additives within their blends. But as these are not closely specified in BS EN 590, budget and own-brand fuels will often not.
These essentials include cetane improves for better combustion, lubricity enhancers and de-coking agents to clean injector nozzles.
“Good servicing is absolutely essential too,” says Steve. “This means the correct OE level fuel filter, changed on schedule.
“Fitting filters with the wrong micron rating is unfortunately very common. This can allow large particles into the fuel injection equipment, leading to premature failures.”
Feather Diesel remind us common rail injectors work at up to 2,500 Bar and 350°C, spraying volumes down to 1mm3 at velocities of up to 1,500 mph at 0.5 millisecond intervals.
Feather Diesel is approved by the world’s leading system manufacturers to repair a full range of diesel components. Find out more by calling 01422 387 800 or click ‘More Details’ below for a free point-of-sale garage information pack.