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dsalinas1939
Top Member
USA
1324 Posts |
 Posted - 12/14/2018 : 12:52:00 PM
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| ok i know i have asked this question before and i am sure i got an answer but i cant remember and i cant find the post i been having a few maxforce dt 466 that as your driving all of a sidden smoke pures from the tail pipe i no its a regen issue becuase when u hit the inhibit regen switch the smoke stops i cant remember what causes that i thought it was a face plugged doc but the one i checked was clear and it was cleaned recently along with the dpf any ideas????? |
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Bluenozer
Top Member
Canada
644 Posts |
Posted - 12/17/2018 : 02:33:42 AM
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egr cooler leaking
pooling around the doc and when its gets hot it starts to evaporate coolant causing smoke from exhaust pipe
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OEM trained in wiring and all engine platforms for over 20 years
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td083
Senior Member
195 Posts |
Posted - 12/17/2018 : 08:31:33 AM
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if the smoke stops when the switch is pressed its the face plugged doc , .>> We do a ton of these ,<< although now we started just replacing the docs and cleaning the dpf . how fast does it stop smoking is it near immediate <<if so it likely wouldn't be a leaking cooler that would continue to smoke . there may be other issues all I can say though>>>>>> everytime<<<<<< we get a smoking during regen / driving and goes away when inhibit is pressed its the face plugged doc everytime . Also what you can do is check the egt temps likely the middle one after the doc is not getting hot enough should be over 1000 may not be exact that is why we started with replacing the docs we found many could not operate to proper temp once they were face plugged or cleaned
.likely yours was cleaned the doc and like I said above it may be clean but unable to increase temp to spec causing the added fuel for regen to pass right through causing smoking , the bus will continually try to keep regen while driving too because the catalyst is faulty hindering any regen from taking place likely you may need a new doc |
Edited by - td083 on 12/17/2018 08:35:47 AM |
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Bluenozer
Top Member
Canada
644 Posts |
Posted - 12/17/2018 : 09:00:29 AM
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cant just force an IH into regen it will only do it if it needs it unlike all other OEMS, and with face plugging this is not normal there is a fault with the engine that causes face plugging
yes you can replace it but it will happen again
the closed crankcase system is what kill these engines (ever wonder why the turbo(s) leak oil at the cac hose , the crank case filter needs changing(hundreds of dollars) so we make them open atmosphere solves alot of issues and tell drivers to never idle always ramp it up |
OEM trained in wiring and all engine platforms for over 20 years
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td083
Senior Member
195 Posts |
Posted - 12/18/2018 : 03:03:01 AM
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When this happens the bus>> isn't being forced into regen<< , while driving the bus will continually be trying to do driving regen adding the additional fuel because the system is faulty ,usually either faceplugged doc or faulty inop doc (wont increase temp properly) reason for the continuing smoke until regen inhibit button is depressed and the smoke will cease immediately that's how we know .>> true on the idle I believe some is operating conditions that exacerbate the issue<< . Although we have a fleet of 1400 buses many these year dts
we found after cleaning a face plugged doc we had a lot of them unable to heat up to proper temp basically not doing there job causing inop regen system causing comebacks like the one described , so they made the decision to start replacing them , cant say for certain that's the best way although we have the benefit of a very large fleet we usually are aware if a fix is reliable or not as we see so many , I strictly do repairs and we at our shop have not had a issue yet with a replaced doc but may very likely in the future who knows , all in all the system has its kinks for sure and no matter what is not the most reliable (regen system) . Not saying this is your issue 100% as were all attempting to assist and are not working or seeing the bus or conditions ourselves , just pointing out what we see continually from our large fleet and all the repair guys from all our shops stay in the loop on issues or general fixes for a known issue the above is the general consensus on how we go about this issue . |
Edited by - td083 on 12/18/2018 03:27:25 AM |
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Bluenozer
Top Member
Canada
644 Posts |
Posted - 12/18/2018 : 06:18:11 AM
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I would like to see a snap shot of one of these doing a passive regen
what are temps across the dpf?(doc in, dpf in and dpf out) and exhaust temp.(manifold sensor)
what is the fuel pressure for the 7th injector? what temp. does it start injecting?
what pressure/position of the egr valve and itv valve?
is the flap after the turbos operational if so what position does it stroke too?
engine coolant temp.?
IAT and IMP readings?
all i'm saying is a doc should not get face plugged without something causing it , we are techs not parts replacers
too many people just throw parts at these systems without knowing or trying to understand that there is alot more to these than just the after treatment system
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OEM trained in wiring and all engine platforms for over 20 years
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td083
Senior Member
195 Posts |
Posted - 12/18/2018 : 07:35:07 AM
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Yea kinda figured this post would go this way :/ anywho as I mentioned earlier we do check the temps of the egts to verify doc operation . Also the year of this bus was not verified although we see most of our issues out of the maxxforce dts 07epa with no 7th injector . And as I stated before I agree the long periods of low idle and or poor route for operating regen likely have input on the face plugging . And as far as parts replacers yes im sure we have some , although we have a huge fleet it tends to streamline diagnosis with the same issue on multiple sister buses (tons ) . We also have many of our staff are prior international dealer technicians as well as all our shops being ase blue seal ( I know ase don't mean anything to ya but just saying ) many multiple masters certified and our fleet ranked in the top ten in the nation . That being said the majority are not parts replacers nor would I slander anyone or assert on a forum as such . Also the first response you made was a direct answer as to what was the cause of his issue without asking any questions you now assert I should ask ? again just trying to give inout to help on what we see all the time , this doesnt mean in this case im right as im only trying to help through hear say . And again once we started replacing the docs we have seen none at least my shop that have then faceplugged although once they get a lot more miles years on them it may happen again as parts all weatr over time but we have had none that my shop knows of that has been a comeback after it was addressed in this manner . Again we have a huge benefit from our fleet size if we see hunddred with the exact symptoms that match symptoms a ,b and c we dont feel the need to spend 3 hours diagnosing the issue when no comebacks have happened through quickly matching symptoms with a known issue and or fix .
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dsalinas1939
Top Member
USA
1324 Posts |
Posted - 12/19/2018 : 10:36:18 AM
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| sory guys am in middle of inspections so thats why my response is slow but the dpf and doc where cleaned recently and the smoke stops as soon as u hit the switch or maybe 2 or 3 seconds havent had a chance to check temps yet because be slammed with inspection but will get info and post it asap |
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regen smoke
