- Before 2007, most diesel engines needed almost no modification to run on biodiesel. With the advent of diesel particulate filters (DPF) that were installed in some post-2007 diesel engines by diesel manufacturers in response to stricter EPA emissions standards, the biodiesel movement has hit a snag. Its higher distillation temperature and boiling point causes it to not vaporize well in the cylinders and is not able to clean the DPF. The remaining fuel on the cylinder walls causes dilution of engine oil.
- Not all manufacturers have implemented DPF, so Caterpillar and Cummins engines should not have this problem. Some Dodge and Mercedes Benz models use urea instead to clean exhaust.
Check with your particular manufacturer to find out if your diesel engine will work with biodiesel. Biodiesel exhibits solvent-like qualities and may cause filters to clog and reduce power. Usually, this can be alleviated by replacing the filter. In some pre-1993 injection systems, certain components, such as fuel pump seals, gaskets and fuel lines, may need to be replaced for the engine to run well on biodiesel. - As a general rule of thumb, blends of B20 or less will require little tinkering with the engine to make it biodiesel-compatible. Blends greater than B20 may require replacement parts, as mentioned previously.
Remember that, even at its optimum, biodiesel performance will not be the same as running it with diesel, as there will be lower power output due to its lower energy content. About 1.1 gallons of biodiesel will take you as far as one gallon of diesel.
Look for a cetane value of 40 or higher and fuel viscosity that is in keeping with diesel itself. Blends of raw vegetable oil often do not have the proper viscosity and may form deposits inside the engine. Biodiesel is similar to diesel fuel number two in viscosity and avoids this problem.
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