Community Forums

resullivan · 09-21-2020, 04:47 AM

Is there a mfg. recommendation for the fluid level to be maintained in the DEF tank while in storage say 2-3 months?

GCSuper · 09-21-2020, 05:55 AM

We just took the Camp Freightliner course and they recommend both DEF and fuel tanks be filled prior to storage. That's always been the recommendation for vehicles being stored. Full tanks have less room for moisture/condensation to form.

palehorse89 · 09-21-2020, 06:36 AM

Just to the "Full" line also..........do not overfill especially with the newer Coach's and the overwhelming def head failure's.
Any type of tank, no matter what it is should always be full, when full, no place for condensation/moisture to form.

TheRod · 09-21-2020, 08:55 AM

Two good Cummins DEF FYIs (note: one is from 2016, not sure if still applicable)

https://www.cumminsfiltration.com/si...es/MB10033.pdf

https://www.cummins.com/news/2016/01...-exhaust-fluid

Note: Paragraph 3, Question number 3: Q: What happens if DEF freezes?

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.

richpatty · 09-22-2020, 08:02 PM

Since DEF is mostly water, and I worry about making sure it is as fresh as possible, I actually keep mine under 1/2 tank (unless I am taking a long trip). Condensation does not matter like it would for diesel since it is water based...

And since it does not get that cold here in NC, I do not worry about freezing.

My 2 cents.

palehorse89 · 09-23-2020, 07:27 AM

Quote:

Originally Posted by richpatty

Since DEF is mostly water, and I worry about making sure it is as fresh as possible, I actually keep mine under 1/2 tank (unless I am taking a long trip). Condensation does not matter like it would for diesel since it is water based...

And since it does not get that cold here in NC, I do not worry about freezing.

My 2 cents.

Quality sensor won't like added moisture....... https://mitchell1.com/shopconnection...%20alert%20you.

ptw · 09-23-2020, 05:21 PM

Quote:

Originally Posted by richpatty

Since DEF is mostly water, and I worry about making sure it is as fresh as possible, I actually keep mine under 1/2 tank (unless I am taking a long trip). Condensation does not matter like it would for diesel since it is water based...

And since it does not get that cold here in NC, I do not worry about freezing.

My 2 cents.

I do the opposite. I keep it filled but let it go down on a long trip. The reason for keeping it full is to minimize the formations of crystals. Here is the Freightliner service bulletin for how to clean the crystals when they become a problem.

richpatty · 09-23-2020, 05:30 PM

Quote:

Originally Posted by ptw

I do the opposite. I keep it filled but let it go down on a long trip. The reason for keeping it full is to minimize the formations of crystals. Here is the Freightliner service bulletin for how to clean the crystals when they become a problem.

Interesting. So what your are saying is that by keeping it as full as possible, you are attempting to prevent the float from being exposed to air (completely submerged in DEF) to prevent crystals from forming and jamming the float?

So I guess you would not worry about how full it was while you are driving around, but keep it full during storage.

Something to think about.

ptw · 09-23-2020, 08:18 PM

Yes, I agree with what you say about trying to keep the DEF fresh. I just don't like to leave it set without being full. Also test DEF occasionally with refractometer. Haven't had a problem. We average about 10,000 miles per year.

richpatty · 09-24-2020, 05:39 AM

Quote:

Originally Posted by ptw

Yes, I agree with what you say about trying to keep the DEF fresh. I just don't like to leave it set without being full. Also test DEF occasionally with refractometer. Haven't had a problem. We average about 10,000 miles per year.

Yea....we only traveled about 2,700 miles so far this year. I may get in another 500 before year end...

DEF is supposed to have a 2 year shelf life, so it should be ok. I always wonder if I keep topping it off, will portions of the DEF get old? I guess I always had the thought that getting it closer to empty is best before filling. But the way things are lately, that is harder for us to do.