Community Forums

Sky_Boss · 06-14-2018, 07:27 PM

I'm about to enter the world of DEF. I know a few things and wonder about a few more.

The coach does not appear to have had much use if any since last November. It looks great on the outside and I think it was stored inside during a Michigan winter. Are there any potential situations that might cause a problem with DEF itself?

While at it, here is something I just read at http://www.discoverdef.com/def-overview/faq/#freeze

A large part of Diesel Exhaust Fluid (DEF) is de-ionized water, do I have to worry about the tank or other parts of the Selective Catalytic Reduction (SCR) system freezing?

Diesel Exhaust Fluid (DEF) freezes into a crystalline slush at 12°F (-11°C) and should not be kept at temperatures above 86°F (30°C). If DEF is frozen on your vehicle, for example overnight or over a weekend, you do not need to take any action. Use the vehicle as you normally would. Truck manufacturers use a variety of heating methods to thaw frozen DEF tanks, including in-tank heating elements. While the thawing process is taking place the vehicle's performance will not be affected (the amount of DEF used will be reduced because a cold engine produces a low level of NOx emissions). In some cases the DEF supply tubes are also heated to prevent freezing or tubes are emptied once the engine is turned off. In short, there is no reason to be concerned about using your SCR truck in cold weather.

I'm certain I have more to learn.

blackhawkscp · 06-14-2018, 07:33 PM

Sky Boss,
This as my first yr with DEF myself. Had a harsh winter (central NY). I had the tank full and had no issues starting or thus far. Be sure to have extra DEF with you in case you run low. Good luck.

flamebuster · 06-14-2018, 07:43 PM

Dirt is the biggest enemy of DEF.systems. Wipe the cap before opening and make sure the pour spout is clean.Don't fill the tank during dusty conditions. You will find spilled DEF leaves a white ugly residue on surfaces. So if you get any DEF on painted surfaces it will be easier to wipe off while it is wet.. It pays to carry an extra gallon or 2 because it can be hard to find in small towns and they tend to price gouge you on the product..The high and low temp. guide lines are for storage DEF not the fluid in the vehicle tank..So other than that drive normally and enjoy the trip..JMHO..Doug

crb478 · 06-14-2018, 08:10 PM

DEF is a necessary pain in the arse! I do not have it in my MH but do in my 2015 f250. I can not argue that it works as the exhaust pipe is clean without any black residue. The temps have not been a problem as the DEF is only injected once every gas tank or so as needed after the engine has warmed up. The down side, watch 2 to 4 mpg disappear when the DEF kicks in just as you are starting to feel good about the mileage you are getting. Keeping a little extra is a good plan, but I don't use that much per year averaging 20k a year. Maybe 2 or 3 containers so that is not a big deal.

kylemcmahon1 · 06-15-2018, 07:43 AM

Depending on how long the coach has been sitting. Def has a shelf life. If what is in the tank has gone bad from lack of us. It could cause problems. May be worth having the def tank drained and filled with new def fluid.

luvlabs · 06-15-2018, 08:20 AM

I take it you are looking at a newer coach than the one you have now. DEF creates a wave of paranoia in diesel owners that does not need to be there.

Freezing - doesn't hurt it at all. DEF is two components, urea and distilled water and freezing will do nothing to it.

Shelf life - heat will degrade it faster but generally no worries if you travel. Fill it up with fresh stuff.

Availability - just about anywhere. Even those little towns have it but if you keep it filled, you won't have to worry about it. Best places to get it? Walmart, truck stops, auto parts stores.

Tank location - does the new coach have the tank mounted on the driver's side (good) or passenger side (no so good). If mounted on the driver's side, you can take advantage of the bulk DEF pumps at truck stops. If the tank is on the passenger side, I would use 4 gallon containers which you can refill from the bulk tanks or buy new ones.

Your best thing to do is fill the DEF tank, drive the coach until your gauge says it's low, fill it up and keep driving.

Bahamaniac · 06-15-2018, 08:45 AM

Add to your check list to monitor your DEF fluid! Last year I met a couple who fried the system by running out! It was an EXPENSIVE mistake!

Cousin Ed · 06-15-2018, 08:57 AM

Walmart sells it for about $7.50 for a 2 1/2 gal jug. It's about the same price at the pump of truck stops; so keep a couple on board. Just rotate them so they don't get old. We get about 100 mpg of DEF.

PanJH · 06-15-2018, 09:25 AM

Quote:

Originally Posted by Bahamaniac

Add to your check list to monitor your DEF fluid! Last year I met a couple who fried the system by running out! It was an EXPENSIVE mistake!

I can't believe that-- when you run out, the engine will be derated and speed will be limited. Some manufacturers will prevent restart until you fill the DEF tank..... no damage/harm is done by running out.

Dbrown57 · 06-15-2018, 09:48 AM

Quote:

Originally Posted by luvlabs

I take it you are looking at a newer coach than the one you have now. DEF creates a wave of paranoia in diesel owners that does not need to be there.

Freezing - doesn't hurt it at all. DEF is two components, urea and distilled water and freezing will do nothing to it.

Shelf life - heat will degrade it faster but generally no worries if you travel. Fill it up with fresh stuff.

Availability - just about anywhere. Even those little towns have it but if you keep it filled, you won't have to worry about it. Best places to get it? Walmart, truck stops, auto parts stores.

Tank location - does the new coach have the tank mounted on the driver's side (good) or passenger side (no so good). If mounted on the driver's side, you can take advantage of the bulk DEF pumps at truck stops. If the tank is on the passenger side, I would use 4 gallon containers which you can refill from the bulk tanks or buy new ones.

Your best thing to do is fill the DEF tank, drive the coach until your gauge says it's low, fill it up and keep driving.

I agree with everything said here. I'm an OEM engineer of DEF systems for 15 yrs.

luvlabs · 06-15-2018, 01:24 PM

Quote:

Originally Posted by Bahamaniac

Add to your check list to monitor your DEF fluid! Last year I met a couple who fried the system by running out! It was an EXPENSIVE mistake!

I think you are just trying to stir up trouble. "Someone you met" is the way all of these false stories start.

No DEF? The engine computer will 1) give you ample warning; 2) go into limp mode.

What could they have possibly "fried".