# DEF refill frequency (2011 335d)



## Pierre Louis (Oct 23, 2011)

Mine went into the 1000 mile warning mode twice. I had no problem filling it up with a funnel the first time, the second time the small bottle from the dealer worked well enough until the next service. My car has 49,000 miles on it so it will be self service from now on. I don't think there is anything special to filling either tank, but can be edumicated, haha.

PL


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## rulonger (Sep 16, 2014)

I had the 1000 miles to NO START warning. It had been about 11,000 miles since last service, so I guess that is about right. I read up on the refilling procedure on some other threads and felt good about being able to avoid the $200 dealership charge. Went to local parts store and purchased the requisite amount - one 1-gal bottle and two 2.5-gal jugs - for a grand total of less than $40. The 1-gal container came with a flexible funnel with a black seal on the dispensing end. 

So I started refilling and the active tank filled easily. Not wanting to overfill, I just added 1-gal to the active tank.

I then proceeded to fill the passive tank. It was slow going and I only got 2-gal in the tank before my patience ran out. I could surely have gotten more since I thought it held 4.5-gal when empty. This observation seems to coincide with SoCalGuy's experience.

Is there a trick to refilling the passive tank? It does not seem that gravity is working.


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## SoCalGuy455 (Mar 1, 2014)

rulonger,

I'm anxious to hear more feedback on this as well. I'm sure you have scoured the YouTube videos as well.

This guy has a nice little system going.....






This one scares me...


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## MotoWPK (Oct 5, 2012)

From descriptions I'd read of the small DEF bottles sold by BMW (and VW and Audi) it appeared the valve on the bottle prevented spillage from overfilling - as the DEF level backed up to the valve it closed. One aspect that wasn't clear was if the insertion of the bottle with valve was necessary to open the DEF fill port in the vehicle, similar to the situation with the misfueling preventor on current BMW's; i.e. there is a cover then you need a specifically configured nozzle to open the port behind the cover (for fueling, that specifically configured nozzle is the diesel nozzle diameter). Part of the reason I suspected this may be the case was due to the number of instances I'd read about people using the small BMW DEF bottle as a funnel. All of this was dispelled when I had the DEF topped recently on my '14 X5 35d.

The SA simply inserted a funnel into the fill ports (active and passive) and filled them using a 2.5 gallon container of DEF. When he noted the DEF starting to back up into the funnel, he was done and removed the funnel. There was some excess DEF, but that is caught by the overflow pans that surround each of the fill ports. What's more, the DEF that spills into the pan drains back to the tank (I expect the main fill line connects to the tank at a level below the drain line from the overflow pan so that when the main line can no longer drain to the tank the overflow drain line still can). This fill arrangement on the current F15's is something not present on the 335d's shown in the videos and makes the filling of DEF simpler without the need for any special bottle.


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## SoCalGuy455 (Mar 1, 2014)

Moto,

I agree 100% that it's a poor design. If there was an engineering need for two tanks, why couldn't one flow into the other with some kind of siphon or overflow valve? Beyond that, why the unnecessarily awkward refill location? Look at how a Chevy truck (and others) does it with both the diesel and DEF ports under the same lid. Beyond that, I really love the car. Rear wheel drive, good MPG, torque, ultimate driving feedback - all while my HK is cranking the Van Halen.....life is good!

https://encrypted-tbn1.gstatic.com/...wuhY_CA4wK65mDFi5I96dTas0n-lr-83sKgMVGgwMulw0


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## mattebury (Feb 2, 2014)

The 328d went to that design for filling DEF tank.


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## Pierre Louis (Oct 23, 2011)

There was no spillage whatsoever using the custom fill bottle with the special valve. What else can I say!

Happy filling!

PL


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## MotoWPK (Oct 5, 2012)

SoCalGuy455 said:


> Moto,
> 
> I agree 100% that it's a poor design. If there was an engineering need for two tanks, why couldn't one flow into the other with some kind of siphon or overflow valve? Beyond that, why the unnecessarily awkward refill location? Look at how a Chevy truck (and others) does it with both the diesel and DEF ports under the same lid. Beyond that, I really love the car. Rear wheel drive, good MPG, torque, ultimate driving feedback - all while my HK is cranking the Van Halen.....life is good!
> 
> https://encrypted-tbn1.gstatic.com/...wuhY_CA4wK65mDFi5I96dTas0n-lr-83sKgMVGgwMulw0


In their training document (a link to which I found on this site, don't have the link at the moment) BMW describes the need for two tanks being to reduce the amount that needs to be heated to have liquid DEF available during times of subfreezing temps (12 deg F for DEF). Essentially, they are only heating about 1/4 of the tank capacity of the system, the active tank (they also heat various lines, valves, the injection pump and valve).

Why they didn't provide for the active tank to overflow to the passive tank to allow for one fill point, I don't know, but suspect it has to do with packaging constraints. The fill points on the F15, in the engine compartment, facing up, are certainly more convenient than on the 335d (or at least whatever series 335d is shown in the videos others have posted). The overflow trays with a drain back to the tanks are also a nicely engineered feature. Now they just need to add a continuous tank level indication.

Back to the system description in the aforementioned BMW training document, before reading it I thought the DEF system was a simple tank, pump and injection valve - boy was I wrong. It is quite complex with many components. One could be forgiven for saying it's an example of German over-engineering. I don't know how it compares to the design used by MB, VW and Audi. I understand DEF is a requirement in Europe as of this year, so there are, in addition, a number of other manufacturers that will have had to address this.


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## rulonger (Sep 16, 2014)

Even with the rudimentary funnel, which came with the Motorcraft container, I did not spill much of the DEF. But it was slow going to fill the passive tank. 

I guess i will go buy the Kruse bottle from the local dealership and see if that improves the flow into the passive tank. A la video posted by SoCalGuy, I will fashion a funnel from that container to complete the fill of the passive tank (it should hold nearly 2.5 gallons more).


Sent from BimmerApp mobile app


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## jfxogara (Oct 26, 2012)

Contrary to what the second youtube video states, I believe you want to fill the top nozzle first as it connects to the passive tank.


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