I was talking with a friend (hi, Bertrand!) about his plan to use a Mercedes Sprinter 4x4 as an overland adventure platform. I mentioned the issue of running an engine designed for ULSD diesel fuel on the high sulfur diesels found in developing countries. I didn't have a good answer, so let's use this thread to share solutions.
Short version: Is there any proven way to run an engine designed for Ultra-Low Sulfur Diesel on high sulfur diesel?
Long version:
To reduce emissions, modern diesels are equipped with complicated and expensive emission control systems. Equipment includes Selective Catalytic Reduction (SCR), supported by aqueous urea injection (Mercedes calls their system Bluetec). Urea helps the SCR remove oxides of Nitrogen (NOx). Electronically-controlled exhaust gas recirculation (EGR) is an older technology to reduce NOx, and many manufacturers use SCR and NOx in tandem.
The SCR system relies on fuel with reduced sulfur content, called Ultra Low Sulfur Diesel (ULSD). ULSD helps in two ways. First, less sulfur in the fuel reduces emissions of oxides of sulfur (S0x). Second, high levels of sulfur in traditional diesel fuel will coat the catalytic converter at the heart the of SCR system. A gummed-up catalytic converter can't be cleaned; it has to be replaced.
The EGR valve also has to be cleaned periodically. This is an issue for engines running ULSD as well as high sulfur fuel.
ULSD has only 15 parts per million of sulfur. Traditional diesel fuel has 500 ppm. ULSD is found at all diesel service stations in USA, Canada, and western Europe. South Africa, Australia and New Zealand have adopted ULSD. In other countries, finding ULSD is a hit-or-miss proposition. Outside capital cities (e.g., Buenos Aires, Santiago, Beijing, Hong Kong) diesel fuel is almost always traditional diesel with 350-500 ppm of sulfur.
A particulate trap in the exhaust reduces the soot produced by a diesel engine. The trap needs to be cleaned periodically, usually by injection of diesel fuel to "burn" at high temperature for a short period. Exposure to high sulfur fuel will gum up the particulate trap, requiring disassembly and cleaning.
All emissions systems are monitored by sensors connected to the engine's control module. When problems are detected, the dashboard displays one or more codes. Failure to rectify the situation causes the control module to put the engine into "limp home" mode, which limits the engine power and vehicle speed. Few mechanics and dealers in developing countries will have the diagnostic tools to identify and fix problems with a vehicle designed to run USA or European emissions controls.
So taking a vehicle that was designed to run on ULSD to a country that continues to use high sulfur diesel is a recipe for expensive problems.
Is there any proven way to run an engine designed for Ultra-Low Sulfur Diesel on high sulfur diesel?
Short version: Is there any proven way to run an engine designed for Ultra-Low Sulfur Diesel on high sulfur diesel?
Long version:
To reduce emissions, modern diesels are equipped with complicated and expensive emission control systems. Equipment includes Selective Catalytic Reduction (SCR), supported by aqueous urea injection (Mercedes calls their system Bluetec). Urea helps the SCR remove oxides of Nitrogen (NOx). Electronically-controlled exhaust gas recirculation (EGR) is an older technology to reduce NOx, and many manufacturers use SCR and NOx in tandem.
The SCR system relies on fuel with reduced sulfur content, called Ultra Low Sulfur Diesel (ULSD). ULSD helps in two ways. First, less sulfur in the fuel reduces emissions of oxides of sulfur (S0x). Second, high levels of sulfur in traditional diesel fuel will coat the catalytic converter at the heart the of SCR system. A gummed-up catalytic converter can't be cleaned; it has to be replaced.
The EGR valve also has to be cleaned periodically. This is an issue for engines running ULSD as well as high sulfur fuel.
ULSD has only 15 parts per million of sulfur. Traditional diesel fuel has 500 ppm. ULSD is found at all diesel service stations in USA, Canada, and western Europe. South Africa, Australia and New Zealand have adopted ULSD. In other countries, finding ULSD is a hit-or-miss proposition. Outside capital cities (e.g., Buenos Aires, Santiago, Beijing, Hong Kong) diesel fuel is almost always traditional diesel with 350-500 ppm of sulfur.
A particulate trap in the exhaust reduces the soot produced by a diesel engine. The trap needs to be cleaned periodically, usually by injection of diesel fuel to "burn" at high temperature for a short period. Exposure to high sulfur fuel will gum up the particulate trap, requiring disassembly and cleaning.
All emissions systems are monitored by sensors connected to the engine's control module. When problems are detected, the dashboard displays one or more codes. Failure to rectify the situation causes the control module to put the engine into "limp home" mode, which limits the engine power and vehicle speed. Few mechanics and dealers in developing countries will have the diagnostic tools to identify and fix problems with a vehicle designed to run USA or European emissions controls.
So taking a vehicle that was designed to run on ULSD to a country that continues to use high sulfur diesel is a recipe for expensive problems.
Is there any proven way to run an engine designed for Ultra-Low Sulfur Diesel on high sulfur diesel?