Just like dirty diesel nozzles, I take notice. So goes it with my urea tank cap on my LML. At each fill (with DEF) I notice white chips of dry stuff that often falls into the tank when removing the cap. I try to clean the cap but invaribly some of the material falls into the opening. I have to ask if others have seen this and know how to handle it?

 

The white chunks is the died up Urea left over from a small spill.

DEF fluid is part water and part urea. whenever you spill some the water will eventually evaporate away and then what is left is dried up urea, or that white flaky stuff you see.


Urea does corrode aluminum so if you ever re use a bottle, completely remove the aluminum tamper proof seal otherwise it will dissolve into the urea and could potentially cause some problems when filing up. DEF systems are very touchy.

 

Thanks for that. I figured they were dried urea however I rarely spill any (too costly) so the next question is, are we supposed to wipe the opening off (and the cap) to prevent it (the white Cra_) from getting dried out and falling into the opening. Then again, if they fall into the tank does it dissolve back to urea? Are any urea salts built-up in the urea tank. Finally, does the tank have a filter that helps prevent that stuff from plugging the urea injector? This could be a reason for the urea system having problems that require the vehicle to be in the shop! Hummmm! Another way to get cash.

 

if you reuse an open bottle of urea one with the aluminum seal under the cap, the seal can corrode and then contaminate the urea. i would think that the dried up urea could be diluted back into the solution but im not 100% certian