DEF Fill Problem

DEF Fill Problem

Filling the DEF tank has become more problematic than expected.  This posting is a follow up to  DEF Level Low – Refill Soon.

We have a friend who uses diesel trucks in his cattle ranching business.  He recommended we purchase our DEF at Buc-ees because their pricing is reasonable and they tend to have the freshest DEF in the area.  We estimated we needed 6.3 gallons.

At Buc-ees in New Braunfels, I got a shopping cart.   After wandering about for 15 minutes (which is fun but not necessarily productive), I finally had to ask for help to find the DEF.  I loaded four of the 2 gallon containers into the cart and headed off to get coffee.   The receipt the cashier gave me had good news.  A 2 gallon container of DEF at Buc-ees is only $4.98.  $2.49 per gallon.  Compared to Sam’s Club pricing ($4.39 per gallon), a good deal.

Buc-ees DEF in 2 Gallon Container
Buc-ees DEF in 2 Gallon Container

Since I wanted to know if my estimate on the amount of DEF needed to fill the tank was accurate, I knew I would need to have some way to measure the amount of DEF we put into the truck.  We have a scale used to weigh luggage.  Our approach to figuring out how much liquid ended up in the DEF tank works like this:

  • Measure each full container and write weight using marker on container.
  • Measure each container (completely or partially empty) after filling and write the weight using marker on container.
  • Assume each full container contains exactly 2 gallons.
  • Average the weight of the completely empty containers to get a weight for the plastic container.
  • For the container that is left partially full, we can calculate the amount of DEF poured from that container.
DEF Used Formula
DEF Used Formula

I weighed the first container and wrote the weight on the top of the container using a permanent marker.  I detached the plastic hose.  Then I opened the cap.  There is foil that needs to be removed.  After getting a screwdriver from the toolbox, I pierced and removed the foil.  The plastic hose that came attached to the first container had defective threads and wouldn’t screw onto the container.  I tried another hose and that seemed to go on OK.  Ready to pour, I inserted the hose into the DEF filler spout and moved the container into pour position.

Filling DEF Tank
Filling DEF Tank

A small amount of DEF went into the tank and then the DEF started overflowing out of the spout onto the floor.  What a mess.  Fortunately Linda had thought to put a metal oil drip pan under the truck below the spout.  But I got DEF all over myself.

Something is definitely wrong.  After more screwing around, cursing and dripping DEF, we decided to go home and eat lunch and figure out our next steps.

In addition to the luggage scale, I need to make sure the following items are handy when filling DEF:

  • Knife or screwdriver to remove foil
  • Rubber gloves to protect hands
  • Industrial sized paper towels to wipe up spills
  • Large metal oil pan to keep spills off concrete

After lunch and having had the benefit of additional Internet search results, we thought that maybe the problem was with the filler tube not pushing a flapper valve down.   We drove up to our favorite Ford dealer to buy Ford DEF and hose.  Ford’s plastic nozzle assembly costs $6.83 and a gallon of Ford DEF cost $6.95.

Following Ford’s instructions and using Ford’s hose, we have the same problem filling our DEF tank.

After taking the truck to the car wash (RV Car Wash), the truck now shows that the DEF tank is full even though we put at most a half a gallon of DEF into the tank.  I’m fairly certain that mcuh of the DEF poured into the tank ended up on the garage floor.

DEF Tank Levels
DEF Tank Levels

The DEF tank holds 7 gallons.  The tank was “empty” and is not “full.”  We estimated it would take 6.3 gallons to fill the tank but instead, it only took 0.5 gallons or less.

Something is wrong.

The next step is to take the truck in for service – DEF Fill Problem Resolution Postponed.




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