Draining DEF from tank - info/pictures

avanti

2014 GWV Legend 3500 I4
Re: Draining DEF from tank

I really wonder how many of these "contaminated DEF" stories are actually cases of user error. This kind of "first-person report from a knowledgable original owner" are more interesting to me than "I work on lots of these and see bad DEF all the time" reports. It's not that the sources are unreliable, it is just that known provenance makes a huge difference.
 

Old Crows

Calypso 2014 View Profile
Re: Draining DEF from tank

I could not sleep ...
I pulled the hose off yesterday . Drained some DEF , but it was crystal clear . I guess , draining tank applies to RV only or low mileage vans , my 2014 has 120k .
Tractor Supply DEF
Good to check anyway
My friend's DEF system failed on his 14 , at 180k . He was buying DEF at Walmart .
He was getting codes for dirty def injector .
:doh::doh: DEF is DEF. Name on bottle or where you buy it doesn't matter. If it is manufactured under ISO 22241 it is saamo-saamo. Never seen DEF without ISO 22241 qualification.

I'm with Avanti....more likely operator problems or contamination while in use.
 
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Old Crows

Calypso 2014 View Profile
Re: Draining DEF from tank

Dennis! Glemo style clamp?????????
 

4wheels

Member
Re: Draining DEF from tank

My friend told me that his buddy was buying def from Walmart and one time could not use it because it smelled and looked like shampoo. :)
I do not know if it is true .
 
Re: Draining DEF from tank

Walmart used to sell name brand (Peak) DEF and must have had a fair inventory turnover because the dates were always recent (a month or so from production). Last time I went in (several months ago) they only carried a private label DEF. I didnt buy it and I no longer use Walmart. I did find Peak at Home Depot and Advance Auto. The Home Depot stuff must not get rotated as I found several old containers in addition to some reasonably new...Not a big surprise. No one at the HD even knew they had it or what it was for. I found it on a bottom shelf below the pneumatic tool accessories display. Good price though.
 

Aqua Puttana

Poly - Thread Finder
Re: Draining DEF from tank

I really wonder how many of these "contaminated DEF" stories are actually cases of user error. This kind of "first-person report from a knowledgeable original owner" are more interesting to me than "I work on lots of these and see bad DEF all the time" reports. It's not that the sources are unreliable, it is just that known provenance makes a huge difference.
I agree.

I haven't reviewed this thread before posting so apologies for possible repeating.

Recently the general consensus on the Forum is that it is best to keep the DEF tank topped up. Apparently some glitches in the program or sensors cause problems when the tank is allowed to drop to the warning level.

:2cents: vic
 

avanti

2014 GWV Legend 3500 I4
Re: Draining DEF from tank

Recently the general consensus on the Forum is that it is best to keep the DEF tank topped up. Apparently some glitches in the program or sensors cause problems when the tank is allowed to drop to the warning level.
Yes. I have been following these arguments closely and I think I am mostly convinced. BUT, it is worth noting that there are two interpretations of the available data:

1) There are glitches in the DEF warning systems that cause erroneous countdown states AS A RESULT of the low-DEF warning per se.

2) There may be REAL PROBLEMS (e.g., bad NOX sensors) that (due to a glitch) lie hidden until a low-DEF condition triggers the error-reporting system.

If #1 is the case, then absolutely we should never permit a low-DEF condition to occur. But, if #2 is true, the best course of action is less clear.

As I said, I am close to signing up for the Full DEF Tank Club (which is a change of position for me). But it is quite possible that this may turn out to be a sweep-it-under-the-carpet approach.
 

MeRob

Member
Re: Draining DEF from tank

Why drain the DEF Tank? If you're concerned about its visual condition...maybe use a piece of acceptable tubing and draw out a sample. If its ugly, flush the tank. I buy a big jug of 'fresh' DEF every Spring and keep it top-up. Maybe Blaming DEF for our NOx problems... is like blaming the air in a tire for a flat.

Anyone know where the mysterious 'DEF FILTER' might be located? ...
 

Sailordive

New member
Re: Draining DEF from tank

I just got the Check Engine+Def warning stating that my def is contaminated. Have had several DEF countdown issues that were just computer related. I filled the DEF after a low DEF warning 2500 miles ago. Any idea how the DEF can be good for 2500 miles, then get contaminated in a closed system? Directions in Operator Manual says to drain and clean tank. OK, I get the drain part, but how do you "clean" this tank? Would this be covered under the Emissions Warranty? Does a clogged EGR valve give a different warning signal? Thanks
 

FleetWise

New member
Re: Draining DEF from tank

FYI on the 2014 and newer sprinters the DEF tank is in the front passenger engine compartment, right behind the bumper and directly below the fill point. According to WIS/NET you need an extraction pump to drain the tank, there is no drain line like the 2011/2012's had.
 

Monafly

2015 2500 short tall 6cyl
Re: Draining DEF from tank

FleetWise is correct. On my 2015 there is no drain. Here's a picture of what the insides looks like. There is clearly a filter (white section on the right in the middle circle) inside that is not replaceable. All of that 'stuff' in the middle is sonically welded to the tank.
 

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Aqua Puttana

Poly - Thread Finder
Re: Draining DEF from tank

What about SUCKING...:thinking:it out with a pump?
DEF is fairly corrosive.

I buy these pumps when on sale. I use them until they quit. One for petroleum products, one for aqueous fluids. Were I to pump DEF I would probably keep that pump dedicated to the fluid. That said, a good rinse with water may clean the pump just fine.

multi-use-transfer-pump
https://www.harborfreight.com/multi-use-transfer-pump-61364.html

I haven't used the Schrader valve option.

vic
 

sailquik

Well-known member
Sailordive,
Yes, the entire DEF system is a major part of the overall emissions control system.
Unless an authorized MB Sprinter dealer can prove that you (or someone not an authorized
MB Sprinter dealer shop) put something into your DEF system that does not meet the standardised
AUS 32 (aqueous urea solution) and ISO 22241 specifications.
They have testers that show DEF purity. If they balk at the warranty, ask them to get out their DEF
Purity meter and show you that your DEF Fluid does not meet the purity standards.
Perhaps there's another way to look at the "keep it full all the time"vs "refill it when you get the low DEF
message" and light on your instrument panel.
Maybe it depends on how much "due dilligence" you apply to keeping your DEF system operational.
I've never had any problems in > 1/2 million miles in Blue Tec Sprinters.
When I see the DEF warning and light, I try to refill the DEF tank with 2.5 gallons of Terra Cair Ultra
Pure DEF as soon as I can.
Like within 100 miles most of the time. I once did not refill it overnight as I had to wait for the local
auto parts store to open in the AM.
Mostly I add the 2.5 gallons within 1/2 hour of the warning.
It's not something that you want to put off until tomorrow or the next day.
Take care of it right away!
Roger
 
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rab01

New member
My Sprinter 3500 Airstream Interstate has a 6ish gallon DEF tank below the sliding door. There is a drain tube sticking up at the rear inside corner. It has a push-and-turn cap.

The DEF tank vent tube (at top of DEF tank) connects to the fill tube just below the fill spout. So when adding DEF it went down the fill and vent tube and created an air lock in the DEF tank. First time I drained the DEF was simply in order to drain the vent tube. Now I use a long-neck funnel to introduce DEF below the level of the vent tube. Fills fine that way. During this draining (after two years) I found that I had about 4 gallons of DEF, and it was completely clear. So I reused it. Later that year I drained the remaining DEF and refilled with new DEF. I diluted the old DEF a lot and sprayed it on my yard as a fertilizer.
 
Outside of the brown tank issue, which makes me wonder if someone left the filler partially open in dusty conditions, clear fluid is not necessarily an indication that the fluid is good. There is a specific ratio of purified water to urea that the system requires. I don't remember the percentage, but it is a window of only a few percent. My understanding is the old fluid, though clear, may suffer from evaporative loss of one of the two components. I believe the water part. This causes the fluid to fall out of spec. If non-Mercedes systems are advanced enough to calculate and throw a code when this is out of spec, then it is likely that Mercedes systems can do the same. Perhaps it is a calculation between the injected amount and the difference between the pre and post catalysts NOX sensors, but I can only guess. Either way MB wants you to pay to have the fluid drained and replaced every two years. Not inspected, and retained/reused if clear.

On a related note, assuming all of the above is correct, if the container that you are using is sealed so as to prevent evaporative loss the "born on" date of the fluid should be less of an issue. This assumes the container has some sort of a vapor proof seal that has to be removed prior to use besides a screw on cap.

This is my understanding of the system after talking to a few diesel mechanics who work on larger rigs combined with using some basic logic. That same logic makes me question if keeping the tank topped up all the time vs. refilling when you get the "reminder" is the best strategy. I was not aware until this post about the corrosion issue of internal sensors, only spilled fluid. But it makes perfect sense that a dry (or partially wet) sensor would suffer from corrosion. Each time I have been reminded to fill up, I have added fluid within 30 minutes or 30 miles. I just happened to be on the highway each time, and felt compelled to easily address a light on my dash by stopping in to get fluid. Dash lights, and low fuel lights just make me nervous I guess.

So not I am thinking the best preventative idea is to keep everything topped up and wet, and to drain the tank each two years like MB says just to make sure the ratios remain within spec.

FWIW...some additional information for context.
 
My source which I just re-read is the 2011 Freightliner Sprinter Maintenance Manual.

I was incorrect. It doesn't say "every two years" in my manual. It says (I am copying and pasting here so nothing is lost): "Emptying and refilling DEF - Fill up the DEF at every Oil Service Plus. Drain off the DEF during every maintenance service, then refill."

on page 9 of the manual. My book shows the "Oil Service Plus" as the equivalent of Service A, and "Maintenance Service" as the equivalent of Service B. I don't know too many people who are doing 10K miles a year or less, so Service B/Maintenance Service should come about every 2 years of less. That's probably where I arbitrarily assigned the 2 year mark in my brain.
 

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