Effects of Biodiesel on Fuel Filters – Conventional and Common Rail Diesel Engines

Effects of Biodiesel on Fuel Filters – Conventional and Common Rail Diesel Engines – Today there are many changes related to the issue of fuel. Obviously, the main issue is the scarcity of fossil fuels that threaten the world. Not only gasoline but also diesel fuel. This is what makes biodiesel one of the solutions that manufacturers offer to continue to produce diesel engine vehicles to date.

Read more: Biofuels are not a big success

In addition to creating alternative fuels (biodiesel), world automotive manufacturers are also developing diesel engines in order to achieve maximum fuel efficiency. One of the innovations is a diesel engine with a common rail system. A system that involves more electronics for the fuel delivery system than older diesel engines. However, it seems that this new technology is not very suitable for biodiesel fuel. Because of some that we meet in the workshop, vehicles with common rail technology often experience problems when using biodiesel. In this article, we try to explore it based on experience in the workshop when repairing diesel vehicles and also expert opinion from one of the leading companies.


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Effects of Biodiesel on Fuel Filters – Conventional and Common Rail Diesel Engines

Effects of Biodiesel on Fuel Filters

We know that currently in diesel vehicles there are two fuel delivery systems. First, there is the old system which we can call a conventional diesel engine, namely a machine that uses a mechanical system to press fuel to the injectors of each cylinder. The second is the common rail system. One of the characteristics of this system is using a suction control valve to provide constant pressure on the high-pressure pipe before entering each injector. The first system does not involve too much electricity, while the second system even uses a control module to control the fuel that enters the combustion chamber.

Read more: 9 Main Causes of Common Rail Diesel Engine Difficult to Start

Two distinctly very different systems from different generations. Not only the system, but it turns out that this has an impact on other things. One of the things that we encounter the most is the difference in impact when we use biodiesel in these two systems. What is the difference? The following is what we encountered in the field regarding the differences between the two systems when using biodiesel.

Effects of Biodiesel on Fuel Filters – Common Rail Engines

For those who often use Biodiesel, you must be aware that there is ‘snot’ or mucus appearing on the fuel filter. The use of Biodiesel in modern diesel engine cars with common-rail technology is an alternative. This is because diesel fuel which has a higher cetane number than biodiesel is always more expensive. In fact, the difference in some countries is quite significant so many choose diesel fuel with low CN as in biodiesel.

Effects of Biodiesel on Fuel Filters
This happens to common rail diesel when using biodiesel. We have not received a scientific explanation for this problem either from the automotive manufacturer or from the official biodiesel manufacturer.

The problem is, that the use of Biodiesel in the long term can have negative effects. One of them is the formation of mucus like a gel on the fuel filter.

One of Mitsubishi’s authorized repair shop service advisors believes that biodiesel can quickly form a slime-like layer on the fuel filter. “The fuel is quite dirty because of the high sulfur, and the fuel filter is the first filter from the fuel line,” he explained.

According to him, biodiesel contains vegetable ingredients that can form a layer of water in the tank. The cause is from the air cavity of the tank which can experience condensation and dew or water particles arise. “Not to mention the vegetable elements from Biosolar can form deposits that bind sulfur, especially if the condition of the old tank is left to cool,” he explained.

Read more: 10 Causes of Black Smoke on Common Rail Diesel Trucks

The layer of water that is sucked in will easily wet the fuel filter paper filter. Meanwhile, additional deposits of vegetable elements quickly bind to the water content in the fuel filter. “If we remove the filter, the fuel filter tends to get wet and slimy. And that can interfere with fuel flow because there is no circulation cavity,” he said.

Effects of Biodiesel on Fuel Filters – Convensional Engine Diesel

Effects of Biodiesel on Fuel Filters
The difference between the new and old diesel filters in conventional diesel engines – Effects of Biodiesel on Fuel Filters.

It’s a different story with the use of biodiesel in conventional diesel engines. Even though we use biodiesel every day until now there have been no problems with the engine. Of course, that’s also no problem with the fuel filter. In fact, if we refer to the conventional diesel engine fuel system, it is certainly not as good as the common rail diesel engine.

Read more: How SCV Works in Common Rail Systems

From some of our experiences, conventional diesel engines have no effect at all whether it uses biodiesel or something else. And until now, scientifically we haven’t found a really precise reason why this is different from the common rail diesel engine.


The use of biodiesel is very good for energy efficiency and overcoming the problem of the threat of the world energy crisis. But with the problems that occur as in the description, it is clear that this is very disturbing for new diesel vehicle owners who all use the common rail system. Meanwhile, the price of diesel fuel (fossil fuel) is very expensive. In these conditions, perhaps the following suggestions can provide a little description and solutions to the problems above;

  1. It’s okay to use biodiesel, especially on common rail diesel, as long as you change the diesel filter more often than usual.
  2. Using a double filter can also be another solution. Dual filters can improve the quality of the fuel that enters the engine.

So, even though there are problems that occur in the use of biodiesel, there are also solutions that we can use. So, there is no longer a problem whether you use biodiesel or use pure diesel fuel.

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