# Crystal like substance engine bay????



## mt3ch (May 4, 2003)

Was washing the x5d after a couple weeks if crappy weather. Noticed this crystal like build up.





















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## floydarogers (Oct 11, 2010)

mt3ch said:


> Was washing the x5d after a couple weeks if crappy weather. Noticed this crystal like build up.


Did you recently get your DEF tank filled? Looks like urea crystals; mechanic splashed DEF around?


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## mt3ch (May 4, 2003)

Yes service 2 at 22k


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## ingenieur (Dec 26, 2006)

mt3ch said:


> Yes service 2 at 22k
> 
> Sent from BimmerApp mobile app


It is soluble and you can clean it away with water.


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## mt3ch (May 4, 2003)

Thanks for the quick reply guys!


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## O8 BMW (Apr 7, 2013)

Definitely DEF. Make sure the caps are screwed in correctly. You might want to remove them and clean them up also.


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## mt3ch (May 4, 2003)

Will do. Thanks!


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## UncleJ (May 7, 2006)

Remember the urea is corrosive too so be sure to get it all off!


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## Flyingman (Sep 13, 2009)

I spilled a bit of it refilling my GL350BT and it crystalized in a matter of minutes on my garage floor. I just wiped it off the side of the car and wheel. I don't think it is that corrosive but definitely wouldn't let it sit on the car parts.

Is Diesel Exhaust Fluid (DEF) corrosive?

Diesel Exhaust Fluid (DEF) is not toxic, harmful or dangerous. In fact, of all the fluids used in a truck, such as diesel, engine oil, brake fluid, antifreeze and windscreen wash, DEF is the least hazardous. However, DEF is corrosive for some metals such as carbon steel, aluminum, copper and zinc, and DEF should not be stored in containers made of these materials. Your DEF supplier can advise you further. ISO22241 provides a list of materials that are recommended and not recommended, but makes it clear that neither list is exhaustive.

Do I need to wear protective clothing when filling up the DEF tank?

Wearing protective clothing is not necessary when handling DEF, however, Diesel Exhaust Fluid (DEF) can stain clothes. If you do spill any DEF on your clothing, rinse it off with water.

What should I do if a spill DEF?

If you spill a small amount of Diesel Exhaust Fluid (DEF), it can be washed away with water or wiped up. If you leave it to dry it will turn into white crystals. These can be washed away with water. If you spill a large amount of DEF then contact your DEF supplier for advice.


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## UncleJ (May 7, 2006)

Essentially the crystals are a salt -- which as we all know is not good for certain metals. It is after all urea. Not as bad as that green stuff that appears on your battery terminals, but nothing you want to leave in your engine bay either. Really harmful only to metal finishes, and probably paint if left on there for long periods of time.:eeps:


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