DEF Head Failure

[Old-RV'er]

I would wager, DEF tank and Catalytic/pollution thing is model specific. I believe mine is on passenger side right under the chassis batteries place. Forward (behind same door) is small storage area I keep leveling ramps/wood blocks. I have always worried that might be a bad place for them. I am going to look at this more and think about what can be put in there which won't catch fire. But if moving down road, lots of air circulation only when stopped could problem arise I think. Neal, is yours like ours?

 

[Neal]

Mine is drivers side just aft of tag axle. As long as airflow occurs the heat from the after treatment system should remain aft. But it is next to the engine. My hunch is it gets hot which decreases the life of the DEF and should be running the tank lower prior to refill. I’m going to start refilling after 1 bar occurs. I was doing at half way. It needs to be cycled out like @redbaron does.

 

[jagpot]

I would wager, DEF tank and Catalytic/pollution thing is model specific. I believe mine is on passenger side right under the chassis batteries place. Forward (behind same door) is small storage area I keep leveling ramps/wood blocks. I have always worried that might be a bad place for them. I am going to look at this more and think about what can be put in there which won't catch fire. But if moving down road, lots of air circulation only when stopped could problem arise I think. Neal, is yours like ours?

My DEF compartment is passenger side but a small compartment with only room for tank and completely walled off.

 

[J&JD]

It needs to be cycled out like @redbaron does.

Maybe. I’m not on board with this practice as of yet. As the tank gets low there is a chance that the small amount in the tank is even more susceptible to heat damage. Again, all of these ideas are simply conjecture. I’m leaning towards the “full tank” group and will be keeping my tank on the full side until I hear a definitive otherwise.

 

[redbaron]

Maybe. I’m not on board with this practice as of yet. As the tank gets low there is a chance that the small amount in the tank is even more susceptible to heat damage. Again, all of these ideas are simply conjecture. I’m leaning towards the “full tank” group and will be keeping my tank on the full side until I hear a definitive otherwise.

I travel in 100+ temps routinely. Traveling from Tx to Mt via utah, new mexico - High heat, low humidty.

I have also spent a good amount of time in Florida, high humidity, High Heat.

1 gallon of contaminated fluid is easily resolved with first stage warning, by adding 2.5 gallons from a jug.

You are right, nothing is proven. I just know what has worked for me on Chevrolet, RAM, & Freightliner systems.

I also change my DEF filter every 3 years.

 

[Neemer]

Regarding heat, I ran a little experiment yesterday. Using my trusty $30 infrared thermometer from Amazon, I measured the temp of the DEF tank after a 45 min run from Richmond to home. Ambient temp was 86 deg at the time.

The DEF tank below the level of the DEF came in at 95 deg. Above the DEF level was 108 deg. The DPF was around 240 deg, and the metal heat shield between the DEF tank and the DPF was about 220 deg.

What does this mean? Hell if I know.

 

[Neal]

Regarding heat, I ran a little experiment yesterday. Using my trusty $30 infrared thermometer from Amazon, I measured the temp of the DEF tank after a 45 min run from Richmond to home. Ambient temp was 86 deg at the time.

The DEF tank below the level of the DEF came in at 95 deg. Above the DEF level was 108 deg. The DPF was around 240 deg, and the metal heat shield between the DEF tank and the DPF was about 220 deg.

What does this mean? Hell if I know.

I think temp of the fluid is crucial and not the exterior of the thick plastic tank. I’m not sure of the construction or thickness or insulating value. Maybe insert a hose and draw out some fluid and get the temp of it? Food grade hoses are available on Amazon.

Sealproof Unreinforced PVC 1/4-Inch-ID x 3/8-Inch OD Food Grade Clear Vinyl Tubing, 10 FT, - - Amazon.com

Sealproof Unreinforced PVC 1/4-Inch-ID x 3/8-Inch OD Food Grade Clear Vinyl Tubing, 10 FT, - - Amazon.com

www.amazon.com

 

[Old-RV'er]

I guess I got confused, my DEF tank is on DS, behind rear wheels (No Tag), forward of the shore power compartment model 3407. My catalytic converter/pollution thing is PS below chassis battery compartment, in that same area is an small walled off storage area, as filled with stuff above. I don't have infrared temp thing, guess that is next on the list. Knowing how warm that compartment gets from the Pollution thing, might be something to know.

DEF Fluid and Temp. Since my Catalytic thing is other side, the only heat generated is most likely coming from transmission area. I don't think I am running much heat into that area. With comment above about level of tank versus heat, I usually on the 250 miles or so trips we are now taking, I might add 1 to 1.5 gallons of def fluid at completion. I filled up from departure location on the way home. The only time I added lots of DEF was when down half and or light came on. Don't know about heat of DEF fluid versus longevity while traveling, something to consider. But while traveling, it's being used and replaced, so new stuff is helping older stuff stay better shape/condition. Long term storage, now that is another can of worms. So far here, only one 90 f day, but early in summer yet.

 

[redbaron]

For those with the refractometer---test with cold, and then heat and test again.

This could be done in your wifes favorite cooking pot while she is shopping for oreo's and ice cream.

 

[turbopilot]

For what it is worth my coach is stored in Thermal, CA. Outside of Death Valley one of the hottest places in the US. I have operated the coach in temperatures up to 122F. So far (since new in 2017) no issues. Rarely let the DEF tank go below 75%. The New Aire after treatment is on the passenger side. DEF storage is on the driver's side in back of the rear wheel and right next to the radiator. During maximum day time desert temperatures the road surface (12" below DEF tank) can exceed 150F.