Winterize Def Tank?

[foxyhigg]

Do you do anything to winterize the Def tank?

[MRUSA14]

No. Below is a quote from Cummins' website:

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Q: What happens if DEF freezes?

A: Vehicle operation is not affected. During vehicle operation, SCR systems provide heat to the DEF tank and lines. The system thaws DEF rapidly and keeps it flowing to the aftertreatment system regardless of the outside temperature.

Diesel Exhaust Fluid is formulated with 32.5 percent urea and 67.5 percent deionized water. In storage or when the engine is not in use, DEF will freeze at 12°F (-11°C). At this concentration level, the urea and the water freeze and thaw at the same rate – ensuring that you always have the correct amount of each. Engines with SCR are specifically programmed for optimal performance at this ratio, which is why it is important to make sure you get a quality brand of DEF that meets ISO specifications.

Cummins Aftertreatment Systems are designed with heated lines and DEF tanks. In extremely cold conditions, they will rapidly thaw the DEF solution. There will be no delay in engine startup.

There is one operational difference to note: Like any water-based fluid, DEF expands when it is frozen (by approximately 7 percent). In cold weather, when the operator shuts the vehicle down, waiting 60 seconds before turning off the battery will allow the fluid to drain back out of the hoses and into the DEF tank.

No anti-gelling additive or freeze point improver should ever be added to the DEF, as they will impede its ability to perform correctly and may damage SCR system components.

[Doctor DEF]

MRUSA14's post citing the Cummins data on freezing of DEF is a great reply to this question.

I've tested DEF after freezing then thawing. As the chemistry predicts, the urea % remains at 32.5, and no cloudiness or other effect is observed. Repeated freeze-thaw cycles have no effect.

DEF is a "eutectic" solution, which is a cool word that means that the freezing point of a solution is at it's lowest temperature (for the various percentages of pure water and technical pure urea) and that as the solution turns from solid to liquid, the 32.5% fraction of urea remains constant.

I'll add the usual "Consult your manual for the OEM's recommendation".

You can also consider the following lessons learned and best practices that we've accumulated during our first year in the DEF business:

1. Verify that the cap is secure on your DEF tank. Inspect to make sure the DEF tank is NOT full to the top.

2. Do a quick inspection of the visible DEF components for abnormal wear (chafing, loose connections, etc.) from this years use of the RV. Address concerns before storing the RV if possible.

3. Avoid storing full retail jugs on the vehicle in case they freeze and then break the cap seal or jug. Most can probably take the freeze-thaw cycle (I'm currently testing this on a jug we make) and the DEF will be fine, but why take any chances with leaks showing up next spring.

We "winterize" our 2013 F350 6.7 diesel by migrating to AZ, but we're very fortunate to be able to do this!

Erich

[Swenster]

Question? We store our mh in an unheated pole barn until we leave for the winter after thanksgiving. Current temp here in northern MN is 20 above BUT the temps are to drop to about zero starting Friday night. If the temp remains below 12 degrees, which happens, what will I encounter when we want to leave? Mh is plugged into 30 amp service. I plan on starting the diesel Aqua Hot a couple of days before we leave. Will the def tank receive any of the heat? If frozen until we start the engine, will it thaw quickly so we can start driving without delay?
All insite is much appreciated.

[brobox]

Tom ,Copied from Marc's post above taken from the Cummins DEF instructions. Looks like no problem.

Cummins Aftertreatment Systems are designed with heated lines and DEF tanks. In extremely cold conditions, they will rapidly thaw the DEF solution. There will be no delay in engine startup.

There is one operational difference to note: Like any water-based fluid, DEF expands when it is frozen (by approximately 7 percent). In cold weather, when the operator shuts the vehicle down, waiting 60 seconds before turning off the battery will allow the fluid to drain back out of the hoses and into the DEF tank.