How to Drain DEF tank?

Depends on the tank used but some have a drain plug on the bottom, others its just easier to use a siphon and drain it into a bucket then flush with known good def.

 

Tip on draining your def tank. - TruckersReport.com
https://www.thetruckersreport.com/truckingindustry...
WebAug 12, 2021 · I thought I would share how I drained my
If no drain plug:
1 - siphon
2 - pump
3 - remove tank
4 - leaf blower (see link)

 

Isnt DEF water based? If thats the case you should be able to rise out and siphon the crusty bits.

 

I bought a little 12 volt electric pump on Amazon for like $30 that will suck semi thick paint out of the bottom of old sprayers. Does a good job and if you clean the pump good afterwards you can use it for other fluids as well. Does not plug up easily.

 

I'd just take it off and dump it.

 

You will never get all the old DEF out without removing the tank. Take it off complete and wash it out and dry completely. While you’re in there, replace the sock/ filter on the pickup pipe.