Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 02-09-2014, 06:13 AM   #1
Join Date: Oct 2013
Location: Fort Wayne In.
Posts: 32
DEF Freeze up

Just wondering if any of you have had this happen this year, while trying to get out of the cool weather. Be safe out there and enjoy the day.

2014 Fleetwood Southwind 36L
chuck5180 is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 02-09-2014, 06:20 AM   #2
Senior Member
JudyH's Avatar
Thor Owners Club
Ford Super Duty Owner
Join Date: Jul 2011
Posts: 892
We had to spend time in Northern Illinois last month, with temps over night of more than 20 below and highs of less than zero. We had no problems with DEF freeze up. But make sure you have the winter blend of diesel in your tank or put in additive to prevent gel. If you fill up in south, and travel north, that is.

Judy & Ralph, w/Molly (the Westie) & Sadie (the Fourche Terrier)
2011 Ford F350 6.7 Lariat
2013 Infinity 3850RL
JudyH is offline   Reply With Quote
Old 02-09-2014, 07:17 AM   #3
Senior Member
GaryKD's Avatar
Newmar Owners Club
Join Date: Jul 2006
Location: Wellington, Florida
Posts: 12,534
The following is from a Q&A site about DEF.

Q. When will DEF freeze ? A. This 32.5% solution will begin to freeze at 12 deg F (-11 deg C). At 32.5%, both the urea and water will freeze at the same rate, ensuring that as it thaws, the fluid does not become diluted, or over concentrated. Unthawing will not cause harm to the product.

Q. How do I keep the DEF from freezing in the tank of a Truck?A. SCR systems are designed to provide heating for the DEF tank and supply lines. If DEF freezes when the vehicle is shut down, start up and normal operation of the vehicle will not be inhibited. The SCR heating system is designed to quickly return the DEF to liquid form.
2005 Newmar KSDP 3910 + GMC ENVOY XUV 37K lbs Moving Down The Road
The Avatar Is Many Times Around The USA
Nobody Knows Your Coach Like Somebody Who Owns One Just Like Yours
GaryKD is offline   Reply With Quote
Old 02-09-2014, 08:01 AM   #4
Senior Member
DavisK's Avatar
Thor Owners Club
Join Date: Feb 2014
Posts: 204
That's the same information I got from GM for my Silverado.
2013 Silverado 2500 HD LTZ CC 6.6L Duramax Diesel
2014 Sunset Trail SF270BH
Holly & Buster, mini Dachshunds
DavisK is offline   Reply With Quote
Old 02-09-2014, 08:32 AM   #5
Registered User
Join Date: Mar 2013
Posts: 1,919
Originally Posted by DavisK View Post
That's the same information I got from GM for my Silverado.
Yup it is the same for all vehicles that use DEF. Im sure GM and others do it but Ford will reverse the DEF pump to clear out the lines of all DEF after the engine is shut down. This will keep the lines from having frozen DEF in it and the DEF will not cause line damage. Once the DEF is thawed in the heated tank, the lines are then refilled for normal use.
jamesrxx951 is offline   Reply With Quote
Old 03-06-2014, 11:23 AM   #6
Senior Member
Commercial Member
Join Date: Feb 2014
Location: Kent, WA
Posts: 127
Good questions, answers, and observations on this post.

I'd like to add the following:

It is important not to overfill the vehicle DEF tank in very cold weather, since DEF expands (like water) when it freezes. An overfilled DEF tank that freezes will likely damage the tank.

The F350 pump back system (and other trucks) serves several purposes: The primary reason is to purge the line at shutdown to avoid boiling off the water in DEF (67.5% water) and leaving solid urea residue in the line/injector which would plug the doser. It also prevents freeze up damage as jamesrxx951 noted.

Jugs of DEF will freeze solid at around 8-10 degrees F. Since most jugs are filled to the top, they burst the seal and cap off when they freeze. I've done this intentionally as part of our company's research. The resulting mess when they thaw is not enjoyable. Don't store retail jugs of DEF in temperatures under 10F.

In the range of 10-16 F, DEF will begin to precipitate urea crystals. I've witnessed this and the process is completely reversible. We've tested DEF after freezing, and the purity and other factors are maintained PROVIDED all the urea is re-dissolved.

Please consider our company a Forum resource for all questions about DEF and DEF equipment. We have all the ISO specifications an a vast library of information about DEF and your clean diesel truck. You can find us in the vendor section under Five Star DEF.


Erich Weinberg and Kathryn Whiting
Five Star DEF
Doctor DEF is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
DEF. Replenishing. ed6713 Sprinter Chassis Forum 3 02-04-2014 03:25 AM
2014 Dutch Star DEF Question jimfryar Newmar Owner's Forum 25 12-16-2013 05:44 PM
Prevent a Freeze? Winter boondocking ? ChuckNJ Monaco Owner's Forum 2 10-07-2013 09:23 AM
winterizing in coach washer R F S MH-General Discussions & Problems 5 09-21-2013 10:39 PM
DEF Consumption Rate gMw Cummins Engines 19 06-12-2013 02:16 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 07:42 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.