Draining DEF from tank - info/pictures

avanti

2014 GWV Legend 3500 I4
I re-bumped into the link where the replace DPF at 2 year mark got logged into one of the folds of my brain. Look at the top of page 30 in the attached doc in this post: https://sprinter-source.com/forum/showthread.php?t=16355

I knew it was more than the manual, but sometimes don't remember where I found/saw things.
Thanks for the interesting link. Just to be clear, though: the referenced text is referring to the DEF lifetime, which is not quite the same things as a recommendation for 2-year flushes. Vehicles driven regularly take care of this issue automatically due to normal DEF consumption. Valuable information for low-mileage vehicles, though
 
Thanks for the interesting link. Just to be clear, though: the referenced text is referring to the DEF lifetime, which is not quite the same things as a recommendation for 2-year flushes. Vehicles driven regularly take care of this issue automatically due to normal DEF consumption. Valuable information for low-mileage vehicles, though
Yeah that's the part I was not so sure about when listening to the recommendation to keep the DEF tank full. I get the "keep the sensors wet" part in order do avoid/reduce corrosion. But you are really never swapping out all the fluid. Run the tank down till the reminder kicks in, and you are using say 80% (ballpark numbers here, so don't quote me on any of them), then topping off with fresh fluid would be more of a swap than the described alternative of keeping everything wet. Lets say you top off on a recurring basis. Maybe the old stuff goes down 33%. That's 67% old 33% new fluid. Compare that to 20% old, 80% new fluid and it could make a bid difference over time.

Not wanting to run the risk of fouling the system due to corrosion, nor wanting to run the risk of only swapping out a lower percentage of the old fluid, led me to the "keep it topped, and swap it out every 2 years" failsafe that I initially referred to.

I'm talking a strategy vs. what Merc. says to do specifically.
 

2004VannaWhite

Big White Box
I realize this a revived post from time gone buy- but... Why disconnect the hose at the fitting on the tank? The opposite end of that hose is a squeeze connector that you remove with your hand and the hose is the "tether length" for a drain hose. It pops out of a recess in the molded tank.
 

SpaceBuckaroo

New member
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.
I'm wondering if I could drill a hole and install a little valve so I can drain the tank.

Otherwise I'll be buying a little hand pump from Harbor Freight tomorrow.
 

Bobnoxious

GONE FISHING
Re: Draining DEF from tank

I'm wondering if I could drill a hole and install a little valve so I can drain the tank.

Otherwise I'll be buying a little hand pump from Harbor Freight tomorrow.

Get plastic not metal Unit as DEF is corrosive. I purchased a plastic air powered model for about the same price of a hand operated unit. Much more convenient. Ensure whatever plastic hose you are inserting into the reservoir is wiped clean. This cannot be over emphasized. Implement measures to prevent foreign object debris FOD fall into the reservoir. Wipe surrounding area of reservoir cap prior to removal and after reinstallation.
 

SpaceBuckaroo

New member
I pumped it out and saved a sample for testing. I ordered a DVD repair manual. I might sign up for the online maintenance manual. After I review the manual, I'll determine if I can remove the tank so I can test the heater and tank sensors.
 

CanSprinter11

New member
I pumped it out and saved a sample for testing. I ordered a DVD repair manual. I might sign up for the online maintenance manual. After I review the manual, I'll determine if I can remove the tank so I can test the heater and tank sensors.
just wondering where I could get the DVD repair manual. In addition, where would I be bale to sign-up for the online maintenance manual?

Having a 2012 Sprinter as a low milage summer van, it would make perfect sense to do some DIY work on my Sprinter as I do on my older W126, 300SE, european style.

I have to say "Thank you" to you guys as I have found quite some info here over the years.
 

Bobnoxious

GONE FISHING
just wondering where I could get the DVD repair manual. In addition, where would I be bale to sign-up for the online maintenance manual?

Having a 2012 Sprinter as a low milage summer van, it would make perfect sense to do some DIY work on my Sprinter as I do on my older W126, 300SE, european style.

I have to say "Thank you" to you guys as I have found quite some info here over the years.
I purchased this. There are less expensive DVD versions but more difficult to install.

https://sprintermanual.com/shop/sprinter-ultimate-service-tool-version-5-0-digital-download-edition/

This is priceless but expensive. https://www.cvtekinfo.com/CVTek/
 

BUSYBOB

2015 LTV Unity TB
I have a 2015 Unity TB and the DEF tank is located behind the bumper on the passenger side. For those forum members with a similar layout, if you drained or pumped out the DEF, how did you do it? I tried inserting a 3/8" tube down the filling port and it stopped at about 18" down but I did not try to force it any further. About halfway down there is a clamp on the fill tube that can be removed perhaps for better access. The underside of the DEF tank is blocked by the wheel well cover.

I have not had any problems with the DEF system (continuous topper) but someday if some bad DEF is added, I would like to be prepared with a fix.
 

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SSTraveler

2014 LTV Unity Murphy Bed
Since I had to have my NOX sensors and DEF heater replaced recently on a trip. I asked to have my DEF tank drained and refilled as part of my 40,000 mile/5 year service. I don't know where I saw it but it is recommended that every 5 years you drain DEF tank and replace DEF. I may plan to do every 30,000 miles or about every 3 years since DEF only has a shelf life of 2 years and I keep my tank routinely topped off. It certainly makes sense to do this sometime in an every 3-5 year period. I think MB charged me around $100 for the drain replace, I had a coupon for $250 off my service so it was easier and cheaper for them to do it versus me figure it out.
 

Bobnoxious

GONE FISHING
Since I had to have my NOX sensors and DEF heater replaced recently on a trip. I asked to have my DEF tank drained and refilled as part of my 40,000 mile/5 year service. I don't know where I saw it but it is recommended that every 5 years you drain DEF tank and replace DEF. I may plan to do every 30,000 miles or about every 3 years since DEF only has a shelf life of 2 years and I keep my tank routinely topped off. It certainly makes sense to do this sometime in an every 3-5 year period. I think MB charged me around $100 for the drain replace, I had a coupon for $250 off my service so it was easier and cheaper for them to do it versus me figure it out.

Unless the vehicle is stored for long periods outside in hot temps or, not driven much. DEF drain and Fill is a waste of money. Just refill after long jurney.

Kinda like fuel, always being consumed and replaced.
 

Bobnoxious

GONE FISHING
I have a 2015 Unity TB and the DEF tank is located behind the bumper on the passenger side. For those forum members with a similar layout, if you drained or pumped out the DEF, how did you do it? I tried inserting a 3/8" tube down the filling port and it stopped at about 18" down but I did not try to force it any further. About halfway down there is a clamp on the fill tube that can be removed perhaps for better access. The underside of the DEF tank is blocked by the wheel well cover.

I have not had any problems with the DEF system (continuous topper) but someday if some bad DEF is added, I would like to be prepared with a fix.
Some tanks have a drain plug some don't. Seems yours may not. Not sure of stabbing a hose down the tank. Not only could introduce contaminates but damage sensitive electronic tank components.
How about a remote drain retrofit to eliminate wheel cover removal to gain acces.

On their hand, how often do you expect the need to drain the DEF tank?
 

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VArover

New member
Has anyone drained the DEF from the tank on the Sprinter 3500 chassis ? We would like to do so and have been told there is a pinch tube on the bottom of the DEF tank (Sprinter 3500) that can be accessed to drain the fluid. Thus you can then add new fresh DEF to the tank.

As our RV sits more than moves and the DEF does have a shelf life of about 2 years (and effected by temperature) it would be safe to drain and fill with fresh DEF as preventative maintenance.

A mechanic stated that the pinch tube on the bottom of the DEF tank is located about 2/3 back (of the cab). This seems like it would be quite far back and would be in the area of the passenger side running board on our LTV Unity. The front area of the wheel well is covered and nothing is visible.

Any help as to the location and access to the bottom of the tank would be greatly appreciated.
TIA :thumbup:
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 .
[/QUOTE
Some tanks have a drain plug some don't. Seems yours may not. Not sure of stabbing a hose down the tank. Not only could introduce contaminates but damage sensitive electronic tank components.
How about a remote drain retrofit to eliminate wheel cover removal to gain acces.

On their hand, how often do you expect the need to drain the DEF tank?
Does anybody know why DEF has a shelf life of 2 years? DEF is 32.5% urea and 67.5% deionized water. Is it because urea decomposes over time or its concentration is no longer 32.5%?
 

pfflyer

Well-known member

481771

New member
So from what I read here, no one has actually figured out how to siphon/pump the DEF from the tank located in the right lower front engine compartment. I know that MB says to evacuate the DEF and actually has a picture of their pump. I would like to "evacuate" the DEF but if the tank does have a flapper valve I agree with Bobnoxious. If tube gets "stuck" there is a larger problem. The reason for wanting to evacuate DEF is because our van will never consume a full tank of DEF within a 2 year period and I know that DEF will age out. Just keeping it full only mixes new fluid with old fluid.
 

Bobnoxious

GONE FISHING
The flap issue is resolved by inserting a larger clean probe of some sorts to prop the flapper open while the extraction tubing is extracted.

Some earlier tanks have a drain plug and some not.
 

pfflyer

Well-known member
My 2015 chassis RV will have to have the bottom portion of the bumper removed to access the bottom of my tank. I sample mine by removing the filler tube on top of the tank. The flap can be manipulated easily from there if you need to. My 2013 gets used almost daily so I only test the DEF I use to top it off but if I remember correctly the top of the tank is not accessible like that.
 

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