How Does Biodiesel
Affect Diesel Engines?

Biodiesel works wonderfully with the older diesel engines. Unfortunately there have been some problems reported with the modern direct injection. Also, a few people have experienced clogging due to improper storage of the fuel.


Benefits of Running Biodiesel:

• The older indirect injection models, which run at lower temperatures, tend to run very well with biodiesel!

• In fact, biodiesel works as a solvent and will clean out the deposits left from running petrodiesel.


Photograph taken by Leo-setä (License: Creative Commons Attribution 2.0 Generic)

• Biodiesel increases the life of the vehicle through its lubricating properties.

• It has a higher cetane rating than petrodiesel.


Potential Problems:

• It has a higher gel point than petrodiesel. (It can be blended with petrodiesel to help this problem.)

• A new test (as of 2008) has been developed that represents the modern turbo-charged/ common-rail/ electronic/ direct-injection diesel engine. This new test has shed some light on the modern diesel vehicle problems with biodiesel.

• When made from oils with high iodine values, (which are the best for cold weather) the fuel runs the risk of polymerizing (turning into an insoluble plastic-like material). This is even more likely when it is exposed to high temperatures. Polymerization can cause deposit build-up and result in fewer miles to the gallon.

• Modern direct injection models run at hotter temperatures, higher pressures and are more likely to have problems with build-up than indirect injection.

• Biodiesel degrades quicker than petrodiesel. In the vehicle’s system it is exposed to water, heat, oxygen and impurities, which accelerates its degradation. Problems with it deteriorating are mostly seen in vehicles that are not used regularly, such as seasonal vehicles. As it degrades it becomes more susceptible to bacteria and algae growth, which can cause fuel injector corrosion or blockage, fuel system blockage, and pump seizures.


Cases of Trouble:

• Berkeley had two trucks running on B100 that had their

engines fail due to algae growth . They experienced clogged filters and fuel injection pipes.

• Roaring Fork Transit Agency in Colorado switched all of its busses to run on B5. They had problems due to algae growth in the fuel. It was found in transfer pumps and fuel tanks. It was only found in fuel that had been sitting for a long time. The problem was fixed with an anti-algae additive (a biocide).


In Summary...

If you haven't already purchased a diesel vehicle, it seems the better choice would be to go with one of the older styles. The new diesel design seems to run too hot to be trouble free for biodiesel. If you have an older diesel vehicle, the reports all seem to be great... increased lubricity, and cleansing effects!

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