Portland's older trucks have not experienced any problems to date. The problem lies in the fact the 2008 Fords use a diesel particulate filter while the older trucks do not. The filters need to be regenerated periodically. This is done by adding extra injection pulses to raise the exhaust gas temperature. The process must be carefully controlled to avoid damage to the filter. Conventional petroleum diesel has specific properties and manufacturers calibrate engines to function properly on standardized fuels. Biodiesel is not a standardized fuel.
Continue reading after the jump.
[Sources: Portland Tribune, Ford]
The problem is that biodiesels are made from many different sources and have different properties. Until recently, the only certified standard commercial biodiesel blend was B5 (five percent bio). A B20 standard was ratified earlier this year but no manufacturer has yet certified engines for B20. Because Ford's engines (along with just about every other diesel manufacturer) have only be tested and verified to work properly with blends up to B5, use of any other fuel is expressly forbidden in the warranty. It's no different if you put nitro-methane in a gas engine; the warranty will not cover engine damage.
ABG contacted Wes Sherwood at Ford and got the following explanation of exactly why the higher blends do not work with the company's latest engines.
Ford is the world's truck leader and constantly innovates with new pickups, including being the first to introduce a clean diesel engine to achieve emissions comparable to gas engines as required by new federal
The new F-Series Super Duty's advanced Ford diesel emissions system, like other trucks in the class, injects precise levels of fuel late inthe combustion cycle to provide heat and fuel to the diesel particulate filter (DPF) to burn off trapped particulates in the DPF during regeneration. A small amount of this fuel, under certain operating
conditions, may migrate past the piston rings and into the crankcase. For normal diesel fuel, and regular oil changes, this is not an issue as much of the fuel in the oil will evaporate between regenerations.
However, biodiesel has a much higher evaporation temperature and does not evaporate appreciably. This cumulative effect can lead to significant amounts of fuel in the crankcase oil.
Ford, like other manufacturers, does not warrant that the engine will perform correctly with use of more than 5 percent biodiesel, which is clearly stated in the warranty.
Additionally, many fleet vehicles spend large amounts of time idling. Ford classifies this usage as severe duty with a corresponding oil change interval of 5,000 miles or 200 engine hours, whichever occursfirst. Every Ford Super Duty diesel engine is equipped with an odometer and an hour meter to aid in proper maintenance.
Portland City Commisioner Randy Leonard seems to think that actions directly contravening the manufacturers operating instructions somehow constitute a defect on the part of the product. So far, it looks more like a defect on the part of whoever in the city of Portland purchased these trucks and either did not read the specifications or chose to ignore them. Unless these engines had only ever been run on B5 or less and still had a problem, the city does not appear to have any grounds for a lawsuit or even demanding that Ford honor the warranty.