DEF Filter change

[Mark S]

I just started reading about replacing the DEF filter. I wasn’t even aware that we had DEF filters on our Seneca’s. I thought I was on top of my maintenance but I must have missed this.

Is the service interval really 200,000 miles or 2 years like I’ve read? When is everyone changing theirs?

Thanks, Mark

[Oma/opa]

Mark
I posted the same question on another site after reading the FMCA article. A couple of people said they changed theirs but since then I reviewed my Cummins documentation and found a recommendation to change at 200,000 miles but no reference to the 2yrs

[GCAT9110]

The DEF filter is said to be for good 200K but that is on a typical commercial truck used daily. What we have seen, especially with RVs left to sit for months, is crystals form on the DEF filter media due to a pure lack of use. When a customer brings his RV in for service and states its been sitting for months we suggest the following. Drain the DEF tank while watching the DEF gauge on the dash. As the tank drains the gauge should lower with it until empty. We have seen empty DEF tanks still read full and you know what kind of curve that will throw to engine control. We pull and inspect the DEF filter, it usually has crystal like formations on the surface of the filter media. Its a paper cartridge so you cant clean it, the older DEF systems used what could be considered cleanable but that style has been replaced with a paper like cartridge. We also inspect the DEF Header and Dosing Injector for engine coolant leaks. DEF headers on older coaches tend to leak due to age. I seldom keep my DEF tank full unless I am heading out for a long trip but I never over fill it. I like the slosh affect of a 3/4 full tank. It keeps the DEF fluid mixed and the level sensor nimble and accurate. I always look for DEF gauge activity indicating DEF consumption which tells me that engine control, the pump and dosing injector are working during particle filter regen. I seldom let my rig idle long term, this slows down the velocity of the exhaust gases letting ash build in the particle filter. I have an idle Kick-up on mine and if I idle I do so at 1000 rpm. We have seen different engine combinations consume different amounts of DEF fluid. In some cases due to driving habits, temperatures and the state of the particle filter very little DEF is used others can go thru 2+ gallons in 1200 miles which could indicate particle filter faults. BTW>Part of the Cummins SRC field campaign was due to degrading catalyst or actually faulty catalyst.

[EA37TS]

Originally Posted by GCAT9110

The DEF filter is said to be for good 200K but that is on a typical commercial truck used daily. What we have seen, especially with RVs left to sit for months, is crystals form on the DEF filter media due to a pure lack of use. When a customer brings his RV in for service and states its been sitting for months we suggest the following. Drain the DEF tank while watching the DEF gauge on the dash. As the tank drains the gauge should lower with it until empty. We have seen empty DEF tanks still read full and you know what kind of curve that will throw to engine control. We pull and inspect the DEF filter, it usually has crystal like formations on the surface of the filter media. Its a paper cartridge so you cant clean it, the older DEF systems used what could be considered cleanable but that style has been replaced with a paper like cartridge. We also inspect the DEF Header and Dosing Injector for engine coolant leaks. DEF headers on older coaches tend to leak due to age. I seldom keep my DEF tank full unless I am heading out for a long trip but I never over fill it. I like the slosh affect of a 3/4 full tank. It keeps the DEF fluid mixed and the level sensor nimble and accurate. I always look for DEF gauge activity indicating DEF consumption which tells me that engine control, the pump and dosing injector are working during particle filter regen. I seldom let my rig idle long term, this slows down the velocity of the exhaust gases letting ash build in the particle filter. I have an idle Kick-up on mine and if I idle I do so at 1000 rpm. We have seen different engine combinations consume different amounts of DEF fluid. In some cases due to driving habits, temperatures and the state of the particle filter very little DEF is used others can go thru 2+ gallons in 1200 miles which could indicate particle filter faults. BTW>Part of the Cummins SRC field campaign was due to degrading catalyst or actually faulty catalyst.

2 plus gallons of DEF in 1200 miles. I wish. My 2020 Accolade has been averaging about 250 to 260 miles per gallon of DEF. I have just under 7500 miles on the coach.

What are other Seneca/Accolade owners getting for DEF mileage?

[javamon]

Originally Posted by EA37TS

2 plus gallons of DEF in 1200 miles. I wish. My 2020 Accolade has been averaging about 250 to 260 miles per gallon of DEF. I have just under 7500 miles on the coach.

What are other Seneca/Accolade owners getting for DEF mileage?

Just returned from a 5k trip. Averaged 450 miles per gallon. I remember seeing a spec somewhere that DEF usage should be 1.5 - 2% of diesel usage.

[Mark S]

Originally Posted by GCAT9110

The DEF filter is said to be for good 200K but that is on a typical commercial truck used daily. What we have seen, especially with RVs left to sit for months, is crystals form on the DEF filter media due to a pure lack of use. When a customer brings his RV in for service and states its been sitting for months we suggest the following. Drain the DEF tank while watching the DEF gauge on the dash. As the tank drains the gauge should lower with it until empty. We have seen empty DEF tanks still read full and you know what kind of curve that will throw to engine control. We pull and inspect the DEF filter, it usually has crystal like formations on the surface of the filter media. Its a paper cartridge so you cant clean it, the older DEF systems used what could be considered cleanable but that style has been replaced with a paper like cartridge. We also inspect the DEF Header and Dosing Injector for engine coolant leaks. DEF headers on older coaches tend to leak due to age. I seldom keep my DEF tank full unless I am heading out for a long trip but I never over fill it. I like the slosh affect of a 3/4 full tank. It keeps the DEF fluid mixed and the level sensor nimble and accurate. I always look for DEF gauge activity indicating DEF consumption which tells me that engine control, the pump and dosing injector are working during particle filter regen. I seldom let my rig idle long term, this slows down the velocity of the exhaust gases letting ash build in the particle filter. I have an idle Kick-up on mine and if I idle I do so at 1000 rpm. We have seen different engine combinations consume different amounts of DEF fluid. In some cases due to driving habits, temperatures and the state of the particle filter very little DEF is used others can go thru 2+ gallons in 1200 miles which could indicate particle filter faults. BTW>Part of the Cummins SRC field campaign was due to degrading catalyst or actually faulty catalyst.

Great explanation and answer. Thank you.

[Mark S]

Originally Posted by javamon

Just returned from a 5k trip. Averaged 450 miles per gallon. I remember seeing a spec somewhere that DEF usage should be 1.5 - 2% of diesel usage.

I consistently get between 30-35 gallons of fuel to one gallon of def, or 3-3.5 percent. Much more than 2%.

I was traveling with a friend this summer with a 2015 F250 pulling a 35’ fifth wheel and he was consistently 600 miles of fuel to a gallon of def. I told him his truck was going to self destruct but it has over 70,000 miles and has been using so little def since new. Go figure.

[GCAT9110]

Originally Posted by EA37TS

2 plus gallons of DEF in 1200 miles. I wish. My 2020 Accolade has been averaging about 250 to 260 miles per gallon of DEF. I have just under 7500 miles on the coach.

What are other Seneca/Accolade owners getting for DEF mileage?

Now that seems excessive? Assuming you are not letting the engine excessively idle and not just puttering around in city traffic I would suggest a visit to Cummins. First determine what engine control software version you are running and then see if their is newer updated version available. A simple update could be the answer. I also would not rule out corrupted software, failed differential pressure sensor, bad data from the exhaust thermocouples and last but not least a failing particle filter. However, all that should trip a fault code. All this data can easily be monitored with the right diagnostic software. Something is telling the PCM to keep regening the particle filter. Normally that would be excessive amounts off soot and ash building up in the catalyst. This causes a delta between the front and rear exhaust thermocouples and the same applies to differential pressure delta across the particle filter. When the engine computer sees these differences it determines that the particle filter is becoming restricted and attempts regen if conditions are right.

[EA37TS]

Originally Posted by GCAT9110

Now that seems excessive? Assuming you are not letting the engine excessively idle and not just puttering around in city traffic I would suggest a visit to Cummins. First determine what engine control software version you are running and then see if their is newer updated version available. A simple update could be the answer. I also would not rule out corrupted software, failed differential pressure sensor, bad data from the exhaust thermocouples and last but not least a failing particle filter. However, all that should trip a fault code. All this data can easily be monitored with the right diagnostic software. Something is telling the PCM to keep regening the particle filter. Normally that would be excessive amounts off soot and ash building up in the catalyst. This causes a delta between the front and rear exhaust thermocouples and the same applies to differential pressure delta across the particle filter. When the engine computer sees these differences it determines that the particle filter is becoming restricted and attempts regen if conditions are right.

Did a little research and Cummins states

"DEF consumption will vary depending on the environment, operation and duty cycle of the equipment you are using. On average, DEF consumption is 3-5% of your total fuel consumption levels."

Based on my records my DEF consumption is approx 3.4 percent so I guess I am within the Cummins stated spec. I don't sit around idling nor do I spend a lot of time in city traffic so that is not a factor. I will say however, I have a lot of miles driving through the mountains of VA, WV, NC, and SC which might be a factor.

[Rustynuts]

This document from Cummins says 2% average.

[Gunfighter]

I did a rough calculation and I think I am between 2 and 3%. Candidly had not been tracking my DEF precisely. I do not fill my DEF tank to full as I do not like to have DEF sitting in the tank growing old over the time between trips. I noticed recently that Walmart has changed the packaging on their brand of DEF and I couldn't find a date code anywhere. Always nice to know how old the DEF you are putting in.

[Rustynuts]

It’s nice with the Bluefire module now you can have a DEF concentration gauge on the dash now. Mine shows at 32% and optimal is 32.5%. I also bought a refractometer to first test any DEF going in the tank. I only fill from jugs.

[Gunfighter]

Originally Posted by Rustynuts

It’s nice with the Bluefire module now you can have a DEF concentration gauge on the dash now. Mine shows at 32% and optimal is 32.5%. I also bought a refractometer to first test any DEF going in the tank. I only fill from jugs.

Brian I have gauge envy, have to figure out how to explain to the boss why I need a BlueFire! I did buy a refractometer some time ago. I have had a derate limp mode once and am doing everything i can to avoid again.

[thirdktm]

Just returned from 3,800-mile trip over 20 days.
Got about 575 miles per quart of DEF. Other trips have been in that ballpark.
It's a Jayco Melbourne on the MB Sprinter chassis with the 3.0 liter diesel turbo.

[GCAT9110]

Originally Posted by EA37TS

Did a little research and Cummins states

"DEF consumption will vary depending on the environment, operation and duty cycle of the equipment you are using. On average, DEF consumption is 3-5% of your total fuel consumption levels."

Based on my records my DEF consumption is approx 3.4 percent so I guess I am within the Cummins stated spec. I don't sit around idling nor do I spend a lot of time in city traffic so that is not a factor. I will say however, I have a lot of miles driving through the mountains of VA, WV, NC, and SC which might be a factor.

Mountain driving conditions do not create ideal parameters for regen. That could be part of the issue. I find the best conditions for successful regen is open interstate driving, fairly level terrain, steady throttle or on cruise control 60+mph.