Originally Posted by Sydney
This is a fascinating thread, but I am confused about the proposed degeneration chemistry. Sustained extreme heat will release ammonia as a gas, but this should merely reduce the urea concentration. Is the idea here that the ammonia then precipitates as crystals because of impurities introduced into the DEF tank? From what source?
First off I think it's actually not the crystals forming because of evaporation but rather the actual chemical imbalance caused by the heat the DEF tank is subjected to. I think it's a real concern as some members are running into problems with DEF which is leading to their vehicles being incapacitated for very long periods of time (as dealers try to figure out what's wrong and go through a troubleshooting part replacement process which seems to be a failed catalytic converter). Thus was born this theory that degrading DEF may lead to catalytic converter failure. There now comes in the chemistry as to what happens to the solution DEF when it degrades over time. The theory was that temperature has a significant affect which lead me to what environment and circumstances do those who are having these issues under.
Originally Posted by Sydney
Has anyone found any literature suggesting that degradation of DEF within the vehicle
is seen as a serious concern? I have had no luck finding any evidence to support it. To the contrary, I have only seen reassuring comments suggesting that SCR systems are designed to be tolerant of the likely change in urea concentration accompanying the heat of summer. As Victory Blue puts it:
FICTION: DEF degradation will be a major problem
FACT: Diesel Exhaust Fluid doesn’t degrade nearly as quickly as people assume. For example, at 86°F, DEF has a shelf life of a year. REMEMBER: Do not equate shelf life to spoiling like food, as DEF will not go bad. IT will lose some effectiveness, and the SCR will dose at a higher rate, but it won’t “go bad.”
I would like to know this info as well. But I'd suggest considering not the ambient air temp (as stated 86 degrees) but rather consider the actual temp of the surface the Jeep is parked on. Reason why is we park in parking lots that usually have no shade and are subject to solar rays for most of the day. The problem is a black asphalt parking lot acts just like a natural oven - it gets much hotter than average ambient air temp and then acts as a heat sink holding heat into the evening transferring it to anything parked on it (thus subjecting it to much higher temps for almost the entire day).
I do know this to be fact as I have done track temp testing (I'm a car racer) with a laser thermometer and I've seen readings up to 20 degrees hotter than what a thermometer of ambient air temp says. On the flip side is just being in the shade on natural grass can be 10 degrees cooler. Anyone can repeat this experiment so it's actual fact.
My goal is to try to get some sampling of members from who has had this problem and who has not by gathering data of where they live, where they park, how long, have they had any issues, etc. I also want to better understand the chemistry behind what happens to degraded DEF from exposure to high heat - maybe it upsets the PH balance making it more acidic or base. When you change the temperature it changes the equilibrium of the solution either by evaporation or chemical process into some other concentration.
I'll start with mine.
Ambient air temps this summer have been from the 70's to upper 90's. Moved from KS to NJ this summer as well and live in mountainous area where we see highs of upper 70s this summer.
I park almost always in the shade or garage as well
Tow frequently about 2-3x a month and do mostly highway driving with no short stops.
Only DEF problem I had was from damage to nozzle from splashing through a puddle on highway - took 1 week to get replaced.
Fill DEF tank only to 1/2 tank and keep extra bottle in house in cool / dry place with no shade.
Currently 8,600 miles and no other issues.