DEF filler cap stuck? won't budge

eternam · #1 10-05-2015, 05:18 PM

Hey everyone, first time BMW 2012 X5 x35d owner and Xoutpost poster. I have a dumb issue. I got the no start in 1000 miles DEF warning. I've read how to fill both the active and passive tanks.

I can't for the life of me get the filler cap off of the active tank. Others say you can just twist if off with your hand. Is it just on too tight? Are there release clips or do I need to push and pull a certain way like a prescription bottle?

I also used the red tool with the square end and it just snapped the plastic square off the filler cap.

I did numerous searches and I seem to the only moron who doesn't know how to take the cap off. I have not tried to take the passive tank filler cap off.

Thanks in advance!

Doug Huffman · #2 10-05-2015, 06:20 PM

Is the CCW twist complete and all that is needed is a pull? I have done that before on other twist lock fittings.

eternam · #3 10-05-2015, 06:29 PM

Quote:

Originally Posted by Doug Huffman

Is the CCW twist complete and all that is needed is a pull? I have done that before on other twist lock fittings.

Thanks for the reply. I wish it was that simple. I'd be relieved and feel really stupid at the same time. I've pulled and pushed the cap all sorts of directions. I think a technician may have just twisted it shut too tight.

I'm going to try to use some sort of leverage, like a sheet of rubber. I'm just afraid of snapping or breaking something.

regdfry · #4 10-05-2015, 07:08 PM

You can just add the DEF to the Passive tank. The DEF will be transferred to the active tank via the transfer pump as the vehicle is driven.

Doug Huffman · #5 10-05-2015, 08:26 PM

They're fiber reinforced plastic IIRC. Plastic has a significant thermal expansion coefficient - dL/L. Heat the ring and/or cool the plug.

eternam · #6 10-05-2015, 08:37 PM

Thanks for the suggestions, I'll try both ideas and report back when I get this thing filled up.

Diesel X5 35d · #7 10-05-2015, 09:29 PM

Don't worry about it. Fill the passive tank only. (The one with the filler cap underneath the air intake). This will make the transfer pump run every once in a while and prevent it from seizing up. Wait until a very hot day after a long ride and give it a try, you may be able to open it up in these conditions for the reasons stated above.

Enjoy the fact that you don't drive a VW TDI.

Doug Huffman · #8 10-06-2015, 08:32 AM

Quote:

Originally Posted by Diesel X5 35d

[ ... ] Enjoy the fact that you don't drive a VW TDI.

I exchanged my 2003 TDI for the X5 for my wife's concern for safety, but I'll never see 50+ mpg again (56 mpg once).

ZetaTre · #9 10-06-2015, 02:23 PM

The red handle in the trunk for the transmission release also works to get a bit more leverage to open the cap. The cap has the same square receptical. Otherwise you could use one of those rubber pads you use to open stubborn jars.

Like Mr Huffman suggested, I believe that just refilling the passive tank is a better strategy for a few reason:
1) You limit the amount of air introduced in the active tank possibly reducing the risk of crystallizing urea
2) You don't run the risk of overfilling the active tank that could result in fluid being forced into the various sensors (perhaps that's the reason of their failure)
3) There's a serviceable filter between the passive and active tank which means you don't run the risk of introducing contaminants in the active tank

I also fill up the passive with only a 2.5 gallon jug once I get the warning in the dash: this is again to reduce the risk of overfilling.

Doug Huffman · #10 10-06-2015, 02:57 PM

Thanks, but Diesel gets the credit.

I doubt that urea can crystallize out of DEF in a closed system, it is very soluble in water, way over 1 kilogram per liter at STP, 4 kilograms urea per kilogram water at elevated temperatures.

I note also that urea is not an electrolyte, it does not disassociate into ions in water but maintains its molecular nature, hence microcrystalline.