Doser valve issues

Bradi, I wonder if this is what I've just spent the last two days dealing with ... the outlet from the DPF on my 2011 D13 has been building up with DEF crystals to the point of being half full within 24 hours of being cleaned.

I have cleaned that area, reattached the pipe between the SCR and DPF, and done a regen that lasts for so many hours that I give up and shut the truck off. I have taken the pipe off the next morning and found another big deposit of crystallized DEF, and based on a Volvo bulletin I figured it meant there was a faulty DEF dosing valve. So $360 later I'm doing another HOURS-long regen with a new dosing valve. So far it hasn't let up, with the DEF tank and fuel needles dropping hour by hour. ....... It stutters about once every hour or two for half a second, then resumes. (?!)

I've looked at the flexpipe from the inside but I don't suppose you can REALLY analyze it for leaks, especially with the braided mesh (or heat shield or whatnot) around it. ...... Funny that the crystals end RIGHT where this pipe begins, too.

I may replace this pipe next? I'm becoming exasperated, because I don't know of too many more things to do. And I darned well need to do them. Because I'm derated at 5mph and it insists on doing regens and servicing the SCR system. I have a 4094 FMI 18, which suggests bad DEF or a bad doser, a 5394 FMI 17, which suggests a bad NOX sensor, catalyst malfunction (please no!) or EGR mass-flow failure (HRM!?) or SCR-inlet temperature sensor (??). Funnily enough I had a code for bad inlet NOX sensor, so changed that a month ago. Since some dealers say to replace both at the same time and I didn't, I thought that was the issue when this SCR problem came up, so before replacing the dosing valve, I changed the outlet NOX sensor. Fruitless.

And of course I have a 5246 FMI 0, which means 5 mph derate, because we have elected people to derail our professional lives by putting us at risk of getting rear-ended, and putting the public at risk of rear-ending us. Not to mention destroy our chance of making anything in this business that's already complicated with coming E-logs and potential speed-limit changes that'll vaporize what income remains after one has spent the rest of it on emissions-systems repairs. Really great.

 

PS I sure hope you mean the flexpipe between the SCR and DPF!

 

Replaced that flexpipe today. Hope the problem is gone. Cuz without slicing the old pipe open, I just can't see any cracks.

Some illustrations from the last few days . . .

 

Wow that's crazy man.

 

Very very cool visual!!

I think I will add this pipe to my yearly maint schedule !!

I know mine will go into high idle supposedly for this purpose of crystalized def , awesome to see what it looks like.

I'd be curious if it will burn out after being ran with a good load a few days as long as you're not idling the truck at light......?

 

When it goes into that "high idle" it should usually be doing a regen to get soot out of your DPF. You'll be able to monitor the reduction if you use your stick to go to the AFTERTREATMENT menu on your dash, and then Soot Level Gauge. Not everybody realizes that these nightmares comprise TWO systems: The DPF and the SCR. The DPF is your soot collector. The SCR system is basically your catalytic converter. DPFs catch carbon. Catalyst catches NOX gases. Failure with one or the other will cause headaches. Let me give you a huge tip: If you ever get derated to 5mph, crawl under and unplug the speed sensor from the back of the transmission where the driveshaft goes in. It'll be on the left side usually. Done. Don't waste $800 on a wrecker.

Maybe def crystals re-vaporize if they get hot enough? All I know for sure is that when they hit the cold air from a cracked flexpipe, they form mid-air and drop to the ground, like you're spraying a garden hose into a -50 freezer. A few crystals in the system aren't a problem. It's a problem that's a problem -- like the air leak in the flexpipe I had.

And for yet another update, I have about 550 miles on that new pipe with no fault codes or anything abnormal going on. The old pipe really must've been cracked on the edge by the flange, right where the crystals were forming. I plan to cut it open with a grinder and see! Might put it on youtube.

 

Any new updates on how your truck is running after replacing the Bellows Pipe?

 

Anybody has a new updates how their truck is running after replacing the Bellows Pipe