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RollinCoal

You can clean the doser but the issue is its not dosing enough def, when they get worn they tend to cut the cycle a bit short as they also "meter" the amount of def when this happens you tend to get SCR efficiency code monitor inlet and outlet nox you need a min of 70% conversion. Cummins with all working as it should will do 80-90% DD engines Ive seen 100% mostly 90+%

mikkhh

Inside of the hole where doser is spraying has got white crust buildup. Will that buildup go away after forced regen or needs to be cleaned?

This truck is having issues with def level/quality sensor now. Will try to pull that sensor from tank.

Rawze

(06-13-2025 )mikkhh Wrote: Inside of the hole where doser is spraying has got white crust buildup. Will that buildup go away after forced regen or needs to be cleaned?

This truck is having issues with def level/quality sensor now. Will try to pull that sensor from tank.

it will not clean itself. you need to clean it good with a wire brush.

mikkhh

Update.

SCR tank level sensor failed and got replaced, but there is still faults related to scr, will pull scr + dpf cans to clean scr doser properly (was not able to clean crust build on truck)

Since this truck is 8x4 with two front steer axles the dpf + scr cans are located in the middle of the truck instead behind the cab like on highway long haul trucks. So the cans are not getting hot enough as fast as highway only trucks. Those have lots of low load time too because they are crawling and waiting while loading up materials for example from a ditch that an excavator is cleaning.

I asked cost for new dpf + scr unit . Dealer told 23 000 usd + taxes . Truck is 4 years old, one company has owned it the whole time, serviced at dealership + oil changes done at every 20 000 miles (to me it seems too much, around 10 000 miles would be ok for mandated trucks) compared to 100 000 mile reccomendation by dealer. Drive axle oil changed out every 40 000 miles.

mikkhh

https://www.peterbilt.com/static-assets/...91-1F1.pdf

Straight from manufacturers website owner's manual for mandate systems on those trucks. But the official dealer in my are has never heard about it.

Page 49 tells how to maintain cans. But in my area is absolutely 0 of those dry cleaning guys, everybody tells to wet clean. I have seen on cars and trucks, after wet cleaning there is visible soot on tailpipes (and if engine was running poorly before there has been black smoke), it means that the filter is not doing it's job. Since the wet cleaning compromised them and reduced back pressure and stopped them holding soot and therefore they are not operational anymore, similar to drilling holes into filter. Also now it takes longer for them to heat up and that is why there is increased fuel consumption, increased idle rpm and also after washing filters there is white smoke on startup, since extra fuel is injected to warm up those cans fast to get them to working temperature.

mikkhh

Well well, those DPF cans have been wet cleaned like one and only official dealership around here suggested. Absolutely horrible advice and goes against the aftertreatment systems owner's manual (either DRY CLEAN or REPLACE cans) that is available on Paccar website.

New DPF is like 25k usd from dealer... And those same Paccar manuals that are available for FREE on official Paccar website mention those needs for cleaning and checking of sensors. Yet it seems like dealership has not checked those sensors (or maybe I am wrongly accusing them and IMAP sensors do get plugged with soot in less than 20 000 miles) and has replaced those expensive nOx sensors. Turbo replacements would not have been that far away in terms of next "repairs" (some other brand dealerships openly admit, that they have no idea what is going on, we will just replace parts randomly until we find out what is wrong and you will be charged for all repairs not only for the part that was the culprit in the first place). Maybe they have hard time reading or understanding English? Some who work at dealer even claim that they have never ever heard about those manuals on Paccar website.

Going to talk with a small fleet owner about repairs and what issues there are on trucks (has about 50 trucks, kept no more than 600 000 miles and all are purchased brand new). He mentioned something about the need to replace turbos on those MX13 's .