Effects of Water On Diesel Fuel and Oil
Premature engine ware including pitting of bearings is a indication of water contamination. The water has two effects; it causes corrosion of the surfaces, and it also disrupts or degrades the mechanism of lubrication. Rolling bearing lubrication is by elastohydrodynamic action (EHL or EHD lubrication), and the presence of water tends to inhibit the formation of the EHL film. Even 0.1% of water has a significant effect, and 1% water can reduce bearing life by a factor of 10.
BioDiesel & Contamination By Water
Biodiesel may contain small but problematic quantities of water. Although it is not miscible with water, it is, like ethanol, hygroscopic (absorbs water from atmospheric moisture). One of the reasons biodiesel can absorb water is the persistence of mono and diglycerides left over from an incomplete reaction. These molecules can act as an emulsifier, allowing water to mix with the biodiesel. In addition, there may be water that is residual to processing or resulting from storage tank condensation. The presence of water is a problem because:
- Water reduces the heat of combustion of the bulk fuel. This means more smoke, harder starting, less power.
- Water causes corrosion of vital fuel system components: fuel pumps, injector pumps, fuel lines, etc.
- Water & microbes cause the paper element filters in the system to fail (rot), which in turn results in premature failure of the fuel pump due to ingestion of large particles.
- Water freezes to form ice crystals near 0C (32F). These crystals provide sites for nucleation and accelerate the gelling of the residual fuel.
- Water accelerates the growth of microbe colonies, which can plug up a fuel system. Biodiesel users who have heated fuel tanks therefore face a year-round microbe problem.
- Additionally, water can cause pitting in the pistons on a diesel engine.
