Frozen DEF

[MHarryE]

What number two said. System does not call for DEF until temp is up. My M7 has a symbol saying the DEF is frozen. Continue to run and it will thaw. However if using it at a power level faster than it can thaw, the display will start showing it will limit power to the rate at which it can thaw. An example in the book shows 80%. I've had the display show my DEF is frozen when starting some very cold days but I've never used DEF faster than it can thaw. My high power jobs are tillage and I can't do much on frozen ground. Since I have a KVT transmission, transmission temperature is a limitation. Between 5 and 19 degrees it needs 3 minute warm up before it will propel. At -4 to +4 it needs 5 minutes and -22 to -5 it needs 7 minutes. So the tractor will not even propel until the transmission has time to warm up and during this time the DEF heater is doing it's thing. Its not anything to me because I never start off a tractor or combine in really cold temps without giving it time to warm up.

 

[k0ua]

OK, that all helps my understanding. So I guess the automotive engineers are not crazy after all. I was wondering how in the world could a DEF heater keep your DEF from freezing overnight with killing a battery. Got it now. Thanks all.

 

[3930dave]

DEF is used to reduce the NOx from high combustion temps.

The Nitrogen and Hydrogen from the DEF combine/convert NOx into Nitrogen gas(our atmosphere)and H2O-water vapor.

Since high combustion temps won't happen for some time when very cold,this allows the DEF tank and line heaters time to warm the DEF so it will be ready when needed.

Sounds good as a theory. (Makes sense, not being sarcastic.Well, maybe a bit ).

The one guy I was talking to just had to have a recent model Fx50 towed into the dealer on this issue. Didn't get more details, as we both had to go.

I can't think of many (any actually) other liquid vehicle systems designed to freeze solid. DEF Tanks are likely plastic. How many freeze cycles are the tanks rated for ? I now understand why DEF tank heaters often fail, in what I consider to be relatively young vehicles.

Added complexity. Added weakness. That's true, even w/o liquid loads freezing.

Rgds, D.

 

[3930dave]

Its not anything to me because I never start off a tractor or combine in really cold temps without giving it time to warm up.

Plowing or blowing snow, are the major activities I can picture for Ag stuff re. this DEF issue. Maybe hooking up to a PTO gen in an emergency. I'd expect a good equipment operator (personally owned anyway...) to allow adequate warm up.

I see this as more of a potential issue for road vehicles, than Ag.

Back when TBI gas injection was new (I'm getting old, but beats the alternative :thumbsup, sales reps used to just leave their cars running at Northern Ontario motels overnight in the Winter. TBI wasn't initially quite dialed in right for that type of cold, so the solution was to just leave the car running.....

Guess that's one solution to avoiding a frozen DEF tank......

Sarcasm aside, I'm now wondering why (cost aside) they don't build DEF tanks with "shore-power" 120Vac "block-heaters" ? For what a new diesel costs today, I'd be willing (seriously) to pay at least $400 for that option.

Rgds, D.

 

[MHarryE]

Plowing or blowing snow, are the major activities I can picture for Ag stuff re. this DEF issue. Maybe hooking up to a PTO gen in an emergency. I'd expect a good equipment operator (personally owned anyway...) to allow adequate warm up.

I see this as more of a potential issue for road vehicles, than Ag.

Back when TBI gas injection was new (I'm getting old, but beats the alternative ), sales reps used to just leave their cars running at Northern Ontario motels overnight in the Winter. TBI wasn't initially quite dialed in right for that type of cold, so the solution was to just leave the car running.....

Guess that's one solution to avoiding a frozen DEF tank......

Sarcasm aside, I'm now wondering why (cost aside) they don't build DEF tanks with "shore-power" 120Vac "block-heaters" ? For what a new diesel costs today, I'd be willing (seriously) to pay at least $400 for that option.

Rgds, D.

Its not considered a problem. DEF freezes but is not injected in a cold engine because DEF is used to convert hot NOX into nitrogen and oxygen (air). When cold the engine isn't emitting enough NOX to be a concern. In the meantime the heater is melting enough DEF for use when the engine is hot and producing high power. My partner is now on his second DEF pickup and the only problem he has had is forgetting DEF and having to buy it at a fuel station at more than double our regular cost. His regular job is in Fargo, ND, so frozen DEF is a half year thing.

 

[3930dave]

Its not considered a problem. DEF freezes but is not injected in a cold engine because DEF is used to convert hot NOX into nitrogen and oxygen (air). When cold the engine isn't emitting enough NOX to be a concern. In the meantime the heater is melting enough DEF for use when the engine is hot and producing high power. My partner is now on his second DEF pickup and the only problem he has had is forgetting DEF and having to buy it at a fuel station at more than double our regular cost. His regular job is in Fargo, ND, so frozen DEF is a half year thing.

I understand the chemistry and process as described.

I also don't doubt that the DEF tank is designed to make it through the warranty period, in many northern exposures. Trouble is - last time I looked, emissions warranties (road vehicles) are a lot shorter than they used to be. Realizing that this can be a Don't Care issue, if new vehicles are rotated out fast enough.

Would be interesting to compare failure rates southern USA vs. northern Canada/Alaska, for the same model vehicles. Relative MTBF #'s in Eng terms.

I'm betting DEF tanks and heaters will last longer if they don't freeze.

Rgds, D.

 

[bob is your uncle]

my second year with a 2.8 duramax, had lows of -40C for a week and with enough short trips managed to get a ice jam in the def tank where i had at least 12L of def in the tank and the computer read it as empty. so it was warning me to fill the tank and threatening to speed limit me, as the tank is insulated and there was a giant ice cube in there it took a insane amount of heat to unthaw. drove it in cold after and no more problems thinking it was a combination of the cold and the short trips where the heater just unthawed the fluid around it and ended up in an air pocket just a guess as i don't know the internals of the tank.

 

[3930dave]

my second year with a 2.8 duramax, had lows of -40C for a week and with enough short trips managed to get a ice jam in the def tank where i had at least 12L of def in the tank and the computer read it as empty. so it was warning me to fill the tank and threatening to speed limit me, as the tank is insulated and there was a giant ice cube in there it took a insane amount of heat to unthaw. drove it in cold after and no more problems thinking it was a combination of the cold and the short trips where the heater just unthawed the fluid around it and ended up in an air pocket just a guess as i don't know the internals of the tank.

Yep, that's the type of issue I'm concerned about.

Winter, short trips with a diesel.... challenging enough already, w/o adding an Achilles heel like this.

I'd like to see a "block" heater for DEF tanks, so you can heat from 120vac. Next closest aftermarket solution I know of are these silicone pad heaters:

Silicone Pad Heaters for Engines | Phillips & Temro Industries

Those are listed for metal applications.... can't remember the surface temperatures they typically hit..... wouldn't do much on the outside of an insulated tank though.....

Rgds, D.

 

[DEWFPO]

I'd like to see a "block" heater for DEF tanks, so you can heat from 120vac. Next closest aftermarket solution I know of are these silicone pad heaters:

Those are listed for metal applications.... can't remember the surface temperatures they typically hit..... wouldn't do much on the outside of an insulated tank though.....

Rgds, D.

It would seem to me if you glued a piece of thin metal (approx. size of the bottom of the DEF tank) to the bottom of the tank and then put the silicone pad on it would distribute the heat well. You only need to get the DEF to 1 degree above it's freeze point so you don't need a high wattage heating pad.

DEWFPO

 

[Trillium Farm]

Sarcasm aside, I'm now wondering why (cost aside) they don't build DEF tanks with "shore-power" 120Vac "block-heaters" ? For what a new diesel costs today, I'd be willing (seriously) to pay at least $400 for that option. Rgds, D.

Have you considered a battery blanket for your DEF tank? You could plug it in with your block heater. I'm sure there is way to do this if the tank is outside.