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Old 01-11-2019, 06:42 AM   #50
JRTJH
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Join Date: Mar 2011
Location: Gaylord
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Quote:
Originally Posted by Brentw View Post
Exactly, for the bother fill it your self. Been on def for 5 years now, never heard of the issue with over filling and cracking the tank. Because def does freeze, they use some type of radar guage, notoriously inaccurate and prone to stay on full till it's near empty.
The part I bolded is the reason why overfilling can damage the tank. As DEF freezes, it expands. Overfilling the DEF tank can cause the damage. It only occurs in locations where the temperatures are cold enough to actually freeze the DEF solid. I would make a guess that's in places where the temperature is below zero for days and days and on trucks that sit outside, unprotected from the temperatures. Our truck is in the garage "at home" but if we go to visit someone overnight or take a trip and stay overnight, we usually wind up parked outside... RAM and GM trucks "may" (I don't know) a means to create expansion room in the way their DEF tanks are molded. On Fords the tank can be "filled to the very top with no air gap or room for expansion"...
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