WHEN DEF IS DEATH
How to repair a Def-contaminated fuel system
Way back in the September 2014 issue of our sister magazine,
Dieselworld we talked about diesel exhaust fluid (DEF), which is used as an exhaust treatment in modern diesel emissions systems to reduce the levels of nitrogen oxide (NOX) in the exhaust. Used properly, DEF is a good thing—but used improperly, it can cause serious (and seriously expensive) problems.
A quick Web search will turn up numerous (and, to some, humorous) tales of folks putting DEF into their non-def trucks and cars. Typically this happens when someone pours DEF into the fuel tank on older diesel rigs. We’ve heard stories of vehicle owners who think that if DEF is so good for new diesel trucks, it should be good for their older diesel as well. Also to blame: well-meaning service station attendants, techs at non-diesel shops, and even owners of gas rigs hoping to reap the benefit of increased fuel economy.
The truth, of course, is that DEF is only useful in a rig with a DEF system, which consists of a
DEF contamination of the fuel system causes urea crystals to form, as seen in this control valve.