Ford truck guy Posted January 8, 2015 Share Posted January 8, 2015 I have a 2015 F-350 with the 6.7... This is my first vehicle with DEF fluid... I read that the DEF tank is heated , but here is my question: The truck is primarily a tow vehicle for my RV in warm weather , and my plow truck only when it snows... All the rest of the time it sits... IF the DEF tank is heated , does it need to be running to operate ? Do I need to do something differently?? I do keep it plugged in , not sure if that heater is associated with the block heater ?? Quote Link to comment Share on other sites More sharing options...
Tracy Lawson Posted January 8, 2015 Share Posted January 8, 2015 If I understand correctly it doesn't freeze solid that it just turns into slush. After your vehicle is running the heater will turn it back to liquid. Quote Link to comment Share on other sites More sharing options...
Ford truck guy Posted January 8, 2015 Author Share Posted January 8, 2015 And no worries with the DEF pump freezing ? Quote Link to comment Share on other sites More sharing options...
YT90SC Posted January 9, 2015 Share Posted January 9, 2015 The tank/pump are designed to freeze. It heats when it starts. There are some situations where DEF cannot be heated enough and it will have to be warmed externally. Quote Link to comment Share on other sites More sharing options...
blwnsmoke Posted January 12, 2015 Share Posted January 12, 2015 (edited) When you shut your truck off, you will hear a buzzing sound. It is the DEF pump pumping the fluid out of the lines and back into the tank. The truck does not use DEF the whole time. Upon startup, the truck will turn the heat on to thaw the DEF fluid in the tank and the fluid will fill the lines again. Once again, when you shut the truck off, the lines are pumped clean. You do not need to worry about the fluid freezing. Edited January 12, 2015 by blwnsmoke 1 Quote Link to comment Share on other sites More sharing options...
Ford truck guy Posted January 13, 2015 Author Share Posted January 13, 2015 Thanks to ALL for your responses !!! Quote Link to comment Share on other sites More sharing options...
pilot195 Posted January 20, 2021 Share Posted January 20, 2021 Hello - when the truck is cold (30s or below) until it warms up, there is a pretty good 'chatter' that appears to come from two areas -- under the drivers seat and under the dash up by the drivers feet... it will chatter briefly depending on how cold it is, then for the first few miles of driving it will chatter randomly anytime I hit a bump. Is this possible the DEF pump or lines? thanks Quote Link to comment Share on other sites More sharing options...
Cold Snak Posted February 5, 2021 Share Posted February 5, 2021 I live in the High Rockies at 9,800'. Gets cold here . It's never been a problem. Actually has a longer shelf life in the colder temps than it does in the heat. Quote Link to comment Share on other sites More sharing options...
Buzzman Posted February 13, 2021 Share Posted February 13, 2021 Just make sure you don t keep the DEF tank full to the cap in winter they recomend 3/4 full in winter to leave room for expension when it freeze but like the other say it should not be a issue Quote Link to comment Share on other sites More sharing options...
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