You only have to talk to a mechanic or read a few internet forums to know that over the past few years a considerable number of diesel owners have experienced major fuel system damage, often resulting in extensive repairs to complex fuel pumps, injectors, filters etc costings thousands of dollars.

Surprisingly, many of the vehicles to suffer this problem have been well known, high quality brands. And relatively new models, with some of this damage occurring in vehicles with less than 25,000 kms on the clock.

So what’s going on out there? According to anecdotal evidence from mechanics we’ve spoken to and opinions expressed by various owners in public forums, the problem could be related to the type of diesel fuels being used and their compatability (or lack of) with modern engine technologies.

Today’s common rail diesel (CRD) engines feature levels of engineering refinement, performance and efficiency that are worlds ahead of diesel engines of the past.

The common rail design operates at much higher fuel pressures than older style diesels and therefore has much greater sensitivity to variations in fuel quality and cleanliness.

CRD engines are designed to run on today’s enviro-friendly, ultra low sulfur diesel (ULSD) fuels, which became mandatory for use in Australia from 2006 with a sulfur particulate limit of 50ppm (parts per million). This limit was lowered to 10ppm in 2009.

CRD engines can also run on biodiesel, which is a blend of standard petroleum diesel and non-fossil fuel compounds made from renewable energy sources such as used cooking oil, animal fats and other agricultural products.

These bio-diesel blends are readily available in Australia, in concentrations from five per cent biodiesel (B5) up to 20 per cent (B20) or more.

However, check the warranty statements made by numerous manufacturers about the use of these ‘green’ fuels in their vehicles. Most clearly stipulate that they must conform to the Australian Diesel Standard, which specifies an allowance of up to five per cent biodiesel content (B5). Here’s two good examples:

Toyota Australia: “In the absence of biodiesel blend fuel standards greater than B5 (5% biodiesel blend) and due to the many variations of biodiesel fuel blends under production in our market, such as B20 and B30 (biodiesel blend 20% and 30%) Toyota is not in a position to evaluate the long term effect that these varied biodiesel blends will have on overall engine performance, fuel injection equipment durability, fuel economy and exhaust emission compliance.

“This statement is provided to inform Toyota owners of Toyota’s position with regard to the use of bio-diesel fuels in its products and also serves to confirm that Toyota New Vehicle Warranty will not apply to any failures that are attributable to the use of such fuels.”

Mercedes-Benz Australia: “Daimler AG has determined that diesel fuel containing up to five per cent biodiesel blend, known as B5, which conforms to the fuel standard EN14214 (bio diesel) and EN590 (diesel) meets the technical specifications for all passenger cars and light commercial vehicles equipped with CDI (common rail diesel injection) engines.

“We must also stress that vehicle damage that results from misfueling or from the usage of substandard, non-approved or privately blended fuels may affect your new vehicle manufacturer’s warranty.”

So why are these well designed and precision engineered CRD engines, which are built to provide hundreds of thousands of kilometres of trouble-free service,  suffering premature and expensive fuel system failures?

Are some diesel owners unaware of their vehicle manufacturer’s fuel recommendations and how they can affect their new vehicle warranty?

Are some diesel owners filling up with biodiesel fuel blends greater than five percent (B20, B30 etc) thinking they’re doing the right thing for the environment, but unknowingly destroying their engines?

Are fuel bowsers at some outlets incorrectly labelled, or labelled in such a way as to be hard for the customer to see when choosing which hose to stick in their tank?

Or have you just been unlucky enough to get a dirty batch of fuel, contaminated by water or goodness knows what else?

Unlike petrol, diesel fuel is susceptible to supporting organisms during storage which can be encouraged by the addition of bio-matter. Storage quality requires far more vigilance. Is every outlet doing what’s necessary to ensure clean, uncontaminated fuel?

We’d really like some owner feedback on this, to try and get a handle on what’s going wrong. ends..





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