Crystalized DEF after setting 5 Months

[Richpatty]

I agree with these points…and I am concerned about experiencing these issues since we have not driven as much in the past two years, so I am not turning my DEF over as often. And I would like to drain my tank but there does not seem to be any easy way to do it (Freightliner) and there is no drain plug…

Any thoughts on a work around?

 

[Neal]

People that continue to just top off don't realize they are just aging their DEF fluid, I let mine get down to below half at least before I refill. If I've been sitting for a period of time such as now, I don't store full so I can add DEF to reliquify any crystalization. My hunch is the above has a clogged DPF filter or some other failure in the system and not related to DEF itself.

 

[Rich W.]

People that continue to just top off don't realize they are just aging their DEF fluid, I let mine get down to below half at least before I refill. If I've been sitting for a period of time such as now, I don't store full so I can add DEF to reliquify any crystalization. My hunch is the above has a clogged DPF filter or some other failure in the system and not related to DEF itself.

Or clogged DEF filter - forgot to mention that. Rigs that sit allow the DEF filter to dry out causing crystalized DEF to block it prematurely. Ive seen published maintenance intervals of 150k-300k miles but thats for trucks that run every day. RVs that sit for months need more frequent filter changes. Its an easy job and filters are around $45 for Bosch ($100+ if it says Cummins on the box, even though its the same Bosch filter). I do mine annually and carry a spare.

And unfortunately it could also be a failed DEF pump which will also trigger a “Low DEF” code, adding to the confusion. When my pump failed it was putting out about 5psi, when it should be around 115-150 (or shoot DEF across the shop if you dont have a gauge). And a plugged up filter can lead to early pump failure.

My rig came from Arizona where it only saw less than 3k miles/year of driving. So it sat in Arizona in the heat quite a bit before I bought it two years ago. The things you learn…. I’m hopeful that DEF pressure can be added to the list of data shown on live-data diagnostics in the near future.

As for draining, I simply siphon it out and carry a siphon hose. A hand pump from an old outboard can be handy for this (as well as changing your power steering fluid and filter). Its best to dispose of the old DEF properly, but it is essentially just liquid fertilizer.

 

[bowpulpit]

Such great info from all that answered. Thank You
Freightliner took my friends Ventana LE into the shop about 2pm today.
Will post the outcome once I hear from them.
I purchased a Refractometer on Amazon today. Arrives sometime tomorrow.
Following you'all's advice I will test what's been in my tank these last 3 months and go from there.
More later.
Thanks Again

 

[DavidL]

Fix for crystalized DEF - go camping more

 

[Rich W.]

Such great info from all that answered. Thank You
Freightliner took my friends Ventana LE into the shop about 2pm today.
Will post the outcome once I hear from them.
I purchased a Refractometer on Amazon today. Arrives sometime tomorrow.
Following you'all's advice I will test what's been in my tank these last 3 months and go from there.
More later.
Thanks Again

It will be interesting to hear the results. What year is his coach? Hopefully they will be able to remove, clean and reinstall his existing DEF header (as per the TSB, if thats the problem) and be done with it.

One of the problems Ive encountered is techs guessing their way through these problems and performing tasks, such as forced regen, that are unrelated and do not address the problem. But they rack up the hours in the process.

I had mine in three times for emissions problems while under warranty, and the previous owner had the DEF header replaced as well. Once my emissions warranty ended I made it my mission to bettrer understand the system so that I wont be at the mercy or incompetent or unscrupulous shops. I also use a refractometer but have never seen a reading that would indicate bad DEF.

I also will only go to an approved Freighter shop, but will do everything I can to avoid that, and will boycott Cummins shops if at all possible. Lessons learned….there’s more but I’ll save it for another day.

 

[bowpulpit]

One of the problems Ive encountered is techs guessing their way through these problems and performing tasks, such as forced regen, that are unrelated and do not address the problem. But they rack up the hours in the process.

The saga continues.....
My friends called about 2 hours ago very happy as they were out of Freightliner and on their way from El Paso to Van Horne. I asked what the fix was and they said the Tech did a "forced regen"!
Well....about 15 minutes ago well on their way they called me and said ALL lights were back on! They have not derated and keeping their fingers crossed they can make it to Van Horne for the night and determine next steps tomorrow.
I had just finished reading your post Rich W when they called.

 

[Rich W.]

The saga continues.....
My friends called about 2 hours ago very happy as they were out of Freightliner and on their way from El Paso to Van Horne. I asked what the fix was and they said the Tech did a "forced regen"!
Well....about 15 minutes ago well on their way they called me and said ALL lights were back on! They have not derated and keeping their fingers crossed they can make it to Van Horne for the night and determine next steps tomorrow.
I had just finished reading your post Rich W when they called.

This is one of the problems we face. All regens, passive, active, and manual (aka parked or forced), happen in the DPF in an effort to burn off soot to keep the filter clear, active and manual occuring with the benefit of increased heat provided by injecting diesel into the exhaust.

DEF is injected in the SCR where urea, under high heat, converts to ammonia which in turn through a chemical reaction converts NOX (nitrogen oxide) into nitrogen and oxygen (air).

Thats all great (when it works) but it all happens AFTER the DPF and is completely unrelated to the soot filter which is cleaned by performing regens. But in my experience its the first thing a tech will do as a “rule out”.

Below is schematic of the sysstem: DOC, DPF, then SCR. So you can see that if you have a DEF problem, no efforts to change things in the DPF will address the issue.

Im sure the tech cleared the codes and reset the emissions sensing stuff, which got the owner out of the shop and down the road a ways, but did nothing to address the DEF issue, which is undoutably a faulty senssor, whether in need of cleaning or replacing. Once the sensors detected the problem for a long enough period, the codes came back.

Eventually he will be derated in three stages (see 2,3, and 4 in the second chart). He may not notice the first stage (25%) unless he’s towing and/or climbing grades. It would be interesting to see the codes he is getting on the LBCU. Reading the codes will also help him estimate how far he can drive before the final stage of derate restricting him to 5mph.

In the mean time he should not shut off the engine (limit ignition cycles as the ECM apparently counts them) or get fuel unless absolutely necessary, as these things accelerate the derate process.

Here’s a couple of other items to consider when you have DEF related codes and warning lights:
1 If check engine and the other s DEF lights are on and you fill your fuel tank you will be you will be derated right away.
2 If you idle the engine for more then 1 hour with the same lights as above you will also be derated.

Ive also read that you can get fuel as long as you dont add more than 20 gallons. Some of this is from qualitifed sources, some is anecdotal, and some is probably guess work. But this is the only hope of delaying a full derate.

I would have turned around and headed back to El Paso (Im sure its too late now) since its 120 miles to Van Horn, and to my knowledge there are no resources there that can help. Eventually he will derate. I wouldn't drive any more than absolutely necessary as it is impossible to determine exactly when the final stafe of derate will occur.

 

[Rich W.]

The saga continues.....
My friends called about 2 hours ago very happy as they were out of Freightliner and on their way from El Paso to Van Horne. I asked what the fix was and they said the Tech did a "forced regen"!
Well....about 15 minutes ago well on their way they called me and said ALL lights were back on! They have not derated and keeping their fingers crossed they can make it to Van Horne for the night and determine next steps tomorrow.
I had just finished reading your post Rich W when they called.

PM sent, and not to overwhelm, but of its just a Low DEF code, its probably the tank level sensor and servicable. If its the “dreaded three” it’s a DEF header failure and will require replacement.

Also if his chassis has pre-2016 emissions, it will not have the quality sensor (thankfully) and the level sensor will be mechanical and possibly serviceable. Also if coach is under five years old and 100k miles, all of this is under the emissions warranty.

The three:
1761 – Diesel Exhaust Fluid Tank Volume
3031 – Diesel Exhaust Fluid Tank Temperature
3364 – Diesel Exhaust Fluid Quality

There may be other codes involved as well. Hopefully he can operate his LBCU. If not instructions are readily available.

 

[Rich W.]

This is a page from OTR diagnostics for fault code 3547 (DEF tank empty). He may not have this code but this image shows the drive times before derate. But the thing to remember is that derate is also affected by the conditions listed in post 18. So its a crap shoot and I wouldnt rely on 40 hours of drive time.