Low mileage 2011 f750 Cummins 6.7

[JimT]

That hanging crystalized def shows that the doser valve was leaking. Hopefully they replace it in the campaign. You will need to investigate the tank, pump and lines for buildup and blockages. If the truck will be sitting for extended periods of time you may want to look in to a way of draining and flushing the DEF system as a means to prevent buildup.

Crystalized DEF is supposed to melt around 200-220F or so, plus the solution is largely water to begin with. Boiling water might clean off any buildup, especially in tanks and lines.

One of the best ways to keep the aftertreatment system healthy is too keep the engine running clean and efficient. Don't even think about any kind of aftermarket tuning or performance BS. (Not saying that was your plan, just a warning for anyone reading.) The more boost and power you use, the greater the soot that will be produced and the harder the systems will have to work to remove it from the exhaust.

Also, at that age I would be checking for boost leaks and exhaust leaks. Both will negatively impact how the engine runs and how the aftertreatment system operates.

The 6.7 is a common rail, but not sure if it uses the same type of pump as the 2250/2350/x15 ISX engines. I have a 2006 5.9l common rail dodge and it's a different pump. The 6.7 came out in 2007, long before the troublesome pumps first appeared in the ISX in 2010.