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DEF (Diesel Exhaust Fluid)
I just had my first experience fueling up with DEF. My first attempt didn’t go well. I was filling up with diesel about a week ago and told the clerk that I also wanted DEF. She told me NOT to hang up the diesel handle as it would turn the pump off and wouldn’t be able fuel with DEF. I had my co-pilot hold the diesel handle so that I could try and pump DEF. I couldn’t get it to work so I just skipped it as we had 1/2 a tank of DEF.
So, yesterday, I was needing to fill up with DEF as the needle was approaching E. I told the clerk that I was also needing DEF and told her about the other station where it didn’t work.
I start fueling with diesel and couldn’t get the DEF to work as I followed the procedure the other clerk told me about. Well, those who have DEF, you know that I was told the wrong procedure (you can stop laughing now)!
I had the clerk come out to show me how it worked and told her the procedure that I was told. I hung up the diesel handle and hit the DEF button and filled up.
We drove 2,300 miles on our first tank of DEF.
Mark
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19 Replies
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Thankfully I don’t have to worry about DEF.
Sounds like you can only do just diesel or just DEF? One at a time and not both?
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Mark,
How many gallons is your DEF tank?
Thank you
Bill
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Mark,
the ratio of DEF to fuel is supposed to be around 2%, but at a seminar at Prevost they said with the Volvo they are closer to 1%. So for planning you are likely going to be in the 1 to 2 gallon range per 100 gallons of fuel.
The reason I mention it is because DEF has a 6 month life which was said to be important. As motorhome owners I think we all like to use our coaches in spurts so if you are planning to store it for a while the best plan is to try to run the DEF down as much as practical.
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Also DEF will freeze, and I am concerned about that the bay being heated where the DEF storage is….I agree that it may not be best to fill your DEF tank unless you are using it especially with in a year….
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I am not sure how Prevost setup their DEF tanks, but on trucks, they are heated with engine coolant in the winter. They will freeze solid if parked in cold weather (like here) and will eventually thaw out after the truck has been running long enough to generate enough heat to do it.
Does Prevost install it inside a bay? And have they gone to the ability to fill from either side yet? I know Millennium modified some coaches in the past to fill on both sides and I think they got Prevost’s blessing on that.
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Yes, unless bypassed because of problems they are heated with engine loop. As you said that does not protect them when they are parked…They are mounted on most that I have seen Passanger side third bay…
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It is my understanding Prevost has a supplemental electric heating element. I seem to recall that from training, but verify it. I do not remember if it is on all the time, but logic suggests if it has an electric heater that it is on a “key on” circuit.
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Make sure that you never mistakenly put DEF into the diesel fuel tank.
DEF will cause major damage to the fuel pumps and injectors.We had guy recently fill the diesel tank on one of our
Mercedes work vans with DEF and then drive it until the engine quit. That little mistake cost us over $13k. -
I never give DEF a thought. Out of sight, out of mind. Press on.
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Bill said:
“Mark,
How many gallons is your DEF tank?
Thank you
Bill”
Bill, I just checked the capacities in the manual and we have a 16 gallon tank. Now that I know how to fill it, it won’t be an issue for me. Our Diesel fill and DEF fill are behind the same door on the driver’s side. No DEF fill on the passenger side.
The handle is so different than the diesel handle it would be very difficult to confuse the two. You can’t put Diesel in the DEF tank as the nozzle won’t fit. But, you can put the DEF in the Diesel tank as the nozzle is small. The nozzle on the DEF is about as round as a quarter or little smaller.
Mark
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My X3-45 uses about 1 tank (16 gallons) DEF to two tanks of diesel (208 gallons)
According to most DEF producers I have spoken to, shelf life is about 2 years when kept at “room” temps.
My experience with cold temps ( I live in Maine) DEF will get “slushy” below freezing and probably will throw
VCU code which will go away after you warm engine and stop and start engine 3-5 times. No performance
issues.
Be aware that Volvo (as well as other post 2012 engine manufactures) are having serious D P F issues at high altitudes in cold weather.
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Jim,
I am surprised by the 4% or more DEF you are using when at Prevost training it was emphasized that with the Volvo the stated consumption was as low as 1% but not more than the 2% other engines were using.
They also said it was not uncommon to expect as much as 7 MPG with the Volvo engine. Your thoughts?
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I wonder if putting def in diesel tank of your prevost would destroy fuel system like it does on the smaller diesel pick ups. Down at Ford house last week and man was going though the roof over a repair bill that was around $12,000 bucks for a 3/4 ton with the new powerstroke ford engine. He had put a gallon in the diesel tank. I was thinking no way but the service writer, after man left , said they have to replace everything related to fuel system.
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I have a friend of mine got a brand new Prevost and on it maiden voyage he filled the deisel tank and forgot to put the DEF into its separate system and added it to the fuel tank and drove 500 yards and the Coach froze up and was done. Called his converter and Prevost and they said we will call a tow; you are done. He plugged the fuel injectors and $20K later and some embarassment he was back on the road a little lighter in the wallet.
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These are all the reasons why I don’t use DEF and refuse to use it in my coach. I will never adulterate my coach or my Detroit Diesel with DEF. You other guys can have your DEF.
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