[CaptainGizmo]

Well, the battle continues to find a cause for DEF to be dripping out of an exhaust pipe fitting, and eventually spraying all over the back of the coach and Toad.

   

I've replaced the DEF Doser, reprogrammed the ECM, and replaced the gasket and clamps after the crosspipe where the DEF has been dripping.

I'm not buying the excuse that "some just leak". Can't be right and I'm still not taking no for an answer.

Thought I'd throw it out for some brain power.

[TJ Clark]

WOW that sounds like a mess

[Richard]

Paper towels are my friend when looking for leaks. I realize you have to be careful because of the exhaust temp. And “stuff” don’t run uphill. Meaning I line the potential leak path with the high tech indicators, and go to the highest one that shows liquid.

[CaptainGizmo]

Paper towels are my friend when looking for leaks. I realize you have to be careful because of the exhaust temp. And “stuff” don’t run uphill. Meaning I line the potential leak path with the high tech indicators, and go to the highest one that shows liquid.

Thanks Richard, but I guess I didn’t articulate this leak well enough.

The DEF is being, perhaps, overdosed and causing it to seep through the exhaust pipe joints. So, it’s NOT an external leak, but is a result of too much DEF inside the exhaust.

I’m assuming that even if that joint was perfectly tight, there shouldn’t be ANY DEF fluid going that far after the SCR and then through the exhaust.

Not sure if that makes better sense.

[Richard]

Got it, not being a DEF user, it didn’t dawn on me what was going on. So you either have an overdosing situation or the appropriate amount is not being consumed.

Does your DEF consumption relative to diesel consumption track with what is expected? The reason I ask, is overdosing seems to be a controls issue which could be sensors, pump, or brain. If the dose is appropriate I am going to look carefully at how the DEF distribution system to see why you are not getting the contact time with the exhaust flow. I read where you replaced sensors and reprogrammed the ECM. In my oversimplified approach, I am just trying to cut the problem solving in half without having any intimate knowledge of the nuts and bolts of your setup.

If the doser is not atomizing the DEF, then it would not vaporize, and it would drip as you are indicating. Can you or have you removed the doser, and tricked it into spraying while you watch the spray?

[hypoxia]

I've replaced the DEF Doser, reprogrammed the ECM, and replaced the gasket and clamps after the crosspipe where the DEF has been dripping.

I'm not buying the excuse that "some just leak". Can't be right and I'm still not taking no for an answer.

Is the ECM programed to the factory original settings?  What Horsepower?  What is your DEF consumption rate, ie 50 gallons of fuel to 1 gallon of DEF?  I'm wondering what tests can be run with Cummins Insite relating to DEF?   I'll hook it up if I get time today and see what Insite will do, fortunately I have not had that problem.

[CaptainGizmo]

Jim and Richard…rally good thoughts. We’re all in the same line of thinking.

In fact, I’m going to call PDI to see if they’ve had any experience with this. I seriously doubt they have any control over DEF dosing since it’s an “emissions” thing.

But, I’m surely inclined to think it’s an ECM setting. Years ago, it was suggest that the Doser be replaced annually; but suddenly, that recommendation disappeared and best we can tell, it as because of an ECM update. Hmmmm.

[hypoxia]

It's interesting to see the change in specs of the 2013 ISX15 compared to the 2010-2012 ISX15.  Governed speed went from 2100 to 1800.  There are minute number of people I would trust making changes to the Cummins ECM programming.  There are quite a few discussions on the trucker forums about doser problem troubleshooting.
https://www.cummins.com/engines/isx15-2013?v=671
https://www.cummins.com/engines/isx15-epa-2010?v=696

[CaptainGizmo]

Thanks, Jim, I agree about messing with the settings.

Problem is...I'm having a hard time trusting the Cummins shops, let alone get them to understand the problem!

Also PDI has known these problems and agreed that it's an emissions thing so they don't mess with it.

[xGE_97]

Steve,
This is Bob Repka. I spoke to you several times last August when I was looking at a 2007 Newell for sale in San Diego. Thanks again for all the info you gave me in that process.

Hopefully you found the problem by now, but if you didn't, consider the following. Its possible that fresh air may be entering the exhaust system between the DPF and SCR syatems. If this is the case, the DEF that is atomized into the system may condense at or just after that point due to slightly lowered gas temperature. If that is the case it will pool and leak leading to crystalization. If any of the remaining DEF is liquid rather than mixed in the exhaust gas, it can pass through the SCR and spray out of the exhaust pipe, as you cited. As an example, check out this link: https://www.bigmacktrucks.com/topic/3879...bowflange/
Did you happen measure the emissions? If you have a base reading you may see a difference as well before correcting this.
Your picture showed a crack in the exhaust pipe near the crystals. Is this area between the DPF and SCR?