Reoccurring DEF problem - Freightliner 2013 DD15

If I would have heard about this 5 years ago I could have saved one of my own and about 10 from another district. We had an issue with super short loads clogging the doc, pushing the DPF’s and coating the SCR. I’ve still got one in the shed that’s supposed to be mounted back on a wrecked truck sitting there with this exact problem. I just couldn’t scrap something that took $12k to replace!!!!

Basicly your saying it needs a bake, blow, and def wash (all at the same time.

 

How about doser injector? I had that happen before. Replaced injector and block. Clean out the port when the block is off.

 

I get 4364 and 3364. When the shop resets it with the laptop. It only comes back on when I’m on the highway doing 105km steady. I’m going to change both nox sensors and see what happens.

 

BTW pushed DOC are fixable. I have pushed them back to place with small hydraulic jack. Some dealers do that too now. piece of wood size of DOC must be used so DOC wont be damaged. Only overheated and worn 1 boxes can not be fixed.

 

I think the hot clean exhaust is burning and cleaning the soot very slowly.

 

doser injector and block has noting to do with SCR .

 

So I wonder..... if I could pull up a spare truck divert the exhaust into the inlet of the one-box, set up a little 12v fuel pump to inject DEF through the injector. Into the SCR, and run a couple high temp regens through it. I wonder if I could get it to clean out.

There would still be no way to check if it’s “fixed” without bolting it up thou.... could be a lot of work for no return...

 

I have no idea will it work or not. Without installing and running under load no way to be sure its fixed. Yeah could be a lot of work for no return. I have heard there is a chemical for washing SCR part. Before Detroit was using it but later they stopped using it. Can't remember the name of that liquid.

 

My 2 cents. The 1 box often gets fouled by a coolant or oil leak into the exhaust. Injector o cups rings not seated properly are one example. Over time this will damage your piston rings and cylinder sleeves. A heavy load, or long hill climb, or fast speed during a active driving regen cycle will set conversion fault due to excessive piston blow by and fouled catalyst. A parked regen will pass due to less blow by. New nox sensor's are a waste of $$. Cleared codes after a good parked regen will only keep the fault codes out until your truck calls for another regen and you don't meet the 70% conversion.

 

2014 cascadia with dd15 have three codes I cant get cleared. Passed scr efficiency test. However during regen the nox outlet hits 220 ppm I replaced the sensor to have the same issue. Passed def quality test as well. What's next?