When the regen system kicks in, I know its meant to get hot but how hot ?
I am used to getting funny looks whilst, sat at traffic lights/junctions, as the smoke wafts up from the back of the manifold and the air is full of a toxic burning smell but I thought is this good for the enviroment. I can see the day coming when somebody bangs on the cab door, to tell me the lorry is on fire 
Are all regen systems the same, or is it just a Mercedes thing ?
Could just be mercs. Used to drive a e6 actros and it would do a regen every couple of weeks, even though it done motorway trunking at night on long runs. The heat from the exhaust was similar to standing next to an oven with the door open and it did smell a bit too plus the engine sounded a bit rough during the regen.
Now been driving an e6 scania for a while, and have never noticed it doing a regen once. No excessive heat from the exhaust, no burning smells and engine always sounds fine.
Not sure why the merc done it so often.
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They all stink bad on a forced re-gen and the exhaust temp also goes through the roof as its injecting diesel into the DPF that ignites to burn off the carbon. If you dont want it to do the re-gen in an inconvenient moment there should be a cut out switch. You would use this switch in a flower mill maybe or other places where thereâs flammable material on the ground near the truck.
My Actros sounds like a tractor when on regen and it raises the revs a little and yes the exhaust gets very hot
When our Mercs arrived, we had the fella from MBUK in to ârun us through on the workings of using the buttons on the steering wheel when dropping trailersâ etc etc and we got told that when it goes in to regen, to park up for an hour and let it tick overâŚright oh! And afaik (unless things have changed, Scania do a EGR & an SCR engineâŚone obviously needs adblue & the other doesnât!
Actrosman:
When our Mercs arrived, we had the fella from MBUK in to ârun us through on the workings of using the buttons on the steering wheel when dropping trailersâ etc etc and we got told that when it goes in to regen, to park up for an hour and let it tick overâŚright oh! And afaik (unless things have changed, Scania do a EGR & an SCR engineâŚone obviously needs adblue & the other doesnât!
All new scanias need adblue now. Donât think any manufacturer can achieve euro 6 without using adblue now.
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And another thingâŚwhy have the fuel tank one side and ad blue on tâotherâŚpita having to shunt about in a tight yard cuz the hose doesnât reach other side!
Yip i have had some nice guy wave me done thinking i was on fire with my 14 plate merc while on a re-gen.!!! Was nice of him to warn me but a bit embarrassing.
When on a re-gen it stinks ans the temp is like a bloody oven.
Just dont do what obe of our drivers did , he thought you pressed the re-gen switch when the light came on (cancelling it) choked it up so bad merc had to take it in and do something to it in rge workshop!!!
Boss wasnt impressed with the bill.
Gembo:
They all stink bad on a forced re-gen and the exhaust temp also goes through the roof as its injecting diesel into the DPF that ignites to burn off the carbon. If you dont want it to do the re-gen in an inconvenient moment there should be a cut out switch. You would use this switch in a flower mill maybe or other places where thereâs flammable material on the ground near the truck.
do you mean Active regen ? I was thinking the forced regen is something done in the workshop and they get it so hot 550C + (it starts to glow a little red)
I would guess there are many variations on how they achieve the higher temperatures on an âActive Regenâ, but from what I understand some engines inject diesel into the cylinder after combustion on the down stroke to prolong the burn. it is probably this process that gives that rough feel, a bit like being in too high a gear⌠I think this process takes the DPF up to about 350c, this is the sort of temp needed to burn the soot off. The only way you will get up to these temperatures driving is if yoy are going up hills, sitting on a flat motorway at 56 will probably struggle to get above 250c.
I think it originated from Regens-burgâŚthey forgot to clean the system before exporting it⌠
Our new fhâs have a regen button on the dash. Apparently the truck tells you via the dash display that it needs it, and you do it at an appropriate time
Actrosman:
And another thingâŚwhy have the fuel tank one side and ad blue on tâotherâŚpita having to shunt about in a tight yard cuz the hose doesnât reach other side!
Luckily my rigid has both on same side but I have to block the gate off to fill up as tank is 6 ft back from cab back and our pump is to l/h side of gate
DPF regen has the injection system prolonging the burn by injecting another spray of fuel on the downward power stroke heating the dpf to in excess of 580 degrees.
trucks on short distance/ local work will have regular regens, my FH on long distance autoroutes and max power continuous gradients very rarely regens.
Its all environmental BS really as the dpf collects the soot only to have it all burnt off giving out huge amounts of pollutants in the process. All in the name of factory emissions standards which dont relate to how the engine works in the real worldâŚ
Suedehead:
When the regen system kicks in, I know its meant to get hot but how hot ?
I am used to getting funny looks whilst, sat at traffic lights/junctions, as the smoke wafts up from the back of the manifold and the air is full of a toxic burning smell but I thought is this good for the enviroment. I can see the day coming when somebody bangs on the cab door, to tell me the lorry is on fire
Are all regen systems the same, or is it just a Mercedes thing ?
Sorry in advance for the TLDRâŚ
Hi AndrewG, just seen this post and thought I would add a bit of clarity to the regen/DPF/SCR conversation.
Firstly all regeneration systems are not the same although they do create the same end result.(a clean DPF) Some diesel engine/aftertreatment systems use post injection on the exhaust stroke with turbo actuation/inlet restriction to create the heat needed to perform active DPF regeneration and some use what is sometimes referred to as the â7th injectorâ approach with turbo actuation/inlet restriction to create the required temperature for active regeneration.
The Mercedes engine you are referring to use the '7th injector" approach. This mean that there is a fuel injector mounted behind the turbo in the exhaust outlet elbow that during active regeneration sprays a fine mist of fuel into the exhaust stream, this then reacts with the DOC (diesel oxidization catalyst) to create the heat needed to complete the active DPF regeneration procedure.
Generally there should be no smoke from the exhaust during an active regeneration but you can sometimes get a stinky smell from the exhaust tail pipe. (which strangely enough I quite like!! 
)
Temperatures during active regeneration can get as high as 1200F/650c. I have seen a few cases when the engine or exhaust system has been painted or splashed with garbage that has caused a bit of smoke while it burns off but like I say generally you shouldnât get any smoke during an active regeneration.
I pretty sure most people on here are aware but I sometimes find there is a lot of confusion about DPF and SCR systems so thought I would just add some extra information about the DPF and SCR system.
Sooooooo they are NOT the same thing⌠the systems work one after the other but can also work as stand alone units. As we all know Europe had SCR only first then SCR and DPF and North America had DPF first then DPF and SCR. The DPF takes care of particulate matter (soot) and the SCR takes care for nox, they were combined to meet the latest emission standards by the Euroâs and EPAâs of the world⌠got to love themâŚ
Here is a Video from Volvo that shows a brief overview of how the systems work. (FYI Tier 4 final/stage IV is basically Euro 6)
another good video
Any other question feel free to ask⌠
The English Mechanic:
Suedehead:
When the regen system kicks in, I know its meant to get hot but how hot ?
I am used to getting funny looks whilst, sat at traffic lights/junctions, as the smoke wafts up from the back of the manifold and the air is full of a toxic burning smell but I thought is this good for the enviroment. I can see the day coming when somebody bangs on the cab door, to tell me the lorry is on fire
Are all regen systems the same, or is it just a Mercedes thing ?Sorry in advance for the TLDRâŚ
Hi AndrewG, just seen this post and thought I would add a bit of clarity to the regen/DPF/SCR conversation.
Firstly all regeneration systems are not the same although they do create the same end result.(a clean DPF) Some diesel engine/aftertreatment systems use post injection on the exhaust stroke with turbo actuation/inlet restriction to create the heat needed to perform active DPF regeneration and some use what is sometimes referred to as the â7th injectorâ approach with turbo actuation/inlet restriction to create the required temperature for active regeneration.
The Mercedes engine you are referring to use the '7th injector" approach. This mean that there is a fuel injector mounted behind the turbo in the exhaust outlet elbow that during active regeneration sprays a fine mist of fuel into the exhaust stream, this then reacts with the DOC (diesel oxidization catalyst) to create the heat needed to complete the active DPF regeneration procedure.
Generally there should be no smoke from the exhaust during an active regeneration but you can sometimes get a stinky smell from the exhaust tail pipe. (which strangely enough I quite like!!Temperatures during active regeneration can get as high as 1200F/650c. I have seen a few cases when the engine or exhaust system has been painted or splashed with garbage that has caused a bit of smoke while it burns off but like I say generally you shouldnât get any smoke during an active regeneration.
I pretty sure most people on here are aware but I sometimes find there is a lot of confusion about DPF and SCR systems so thought I would just add some extra information about the DPF and SCR system.
Sooooooo they are NOT the same thing⌠the systems work one after the other but can also work as stand alone units. As we all know Europe had SCR only first then SCR and DPF and North America had DPF first then DPF and SCR. The DPF takes care of particulate matter (soot) and the SCR takes care for nox, they were combined to meet the latest emission standards by the Euroâs and EPAâs of the world⌠got to love themâŚ
Here is a Video from Volvo that shows a brief overview of how the systems work. (FYI Tier 4 final/stage IV is basically Euro 6)
Any other question feel free to askâŚ
Good video.
Question: At 0.52 it says that the DPF continuously oxidizes the (carbon?) particles, is there enough oxygen in the exhaust to do this? Guessing it`s not free oxygen so does this oxygen come from the NOx gases? Or am I asking seriously silly questions? ( YES is a valid answer here).
damoq:
Actrosman:
When our Mercs arrived, we had the fella from MBUK in to ârun us through on the workings of using the buttons on the steering wheel when dropping trailersâ etc etc and we got told that when it goes in to regen, to park up for an hour and let it tick overâŚright oh! And afaik (unless things have changed, Scania do a EGR & an SCR engineâŚone obviously needs adblue & the other doesnât!All new scanias need adblue now. Donât think any manufacturer can achieve euro 6 without using adblue now.
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Iveco have managed to use adblue scr only for euro 6 .no egr required
norb:
damoq:
Actrosman:
When our Mercs arrived, we had the fella from MBUK in to ârun us through on the workings of using the buttons on the steering wheel when dropping trailersâ etc etc and we got told that when it goes in to regen, to park up for an hour and let it tick overâŚright oh! And afaik (unless things have changed, Scania do a EGR & an SCR engineâŚone obviously needs adblue & the other doesnât!All new scanias need adblue now. Donât think any manufacturer can achieve euro 6 without using adblue now.
Sent from my iPhone using Tapatalk
Iveco have managed to use adblue scr only for euro 6 .no egr required
Hi Norb, according to Ivecoâs website they do indeed use EGR and SCR they donât use a DPFâŚyet
But i know what your getting at 
Looks like it all depend on the application the truck is used for.
Good video.
Question: At 0.52 it says that the DPF continuously oxidizes the (carbon?) particles, is there enough oxygen in the exhaust to do this? Guessing it`s not free oxygen so does this oxygen come from the NOx gases? Or am I asking seriously silly questions? ( YES is a valid answer here).
Hi Franglais, no such thing as a silly question⌠there are 2 different kind of regeneration, passive and active.The video is referring to passive regeneration.
Passive regeneration takes place as you are driving along under normal driving cycles, requires no extra inputs from the driver or engine and no extra fuel is injected into the exhaust system.(this is the best possible outcome as all it requires is the engine to be used as intended)
An active regeneration takes place when the engines/aftertreatment computers decides that certain pre-calibrated parameters have been met. The computers will then start an active regeneration and extra fuel will injected into the exhaust system to create the temperature required to clean the DPF.
So the short answer is⌠there is always enough of everything (element) in the exhaust gases to complete passive regeneration, the heat is the only thing that needs to be createdâŚ(by engine load)
Hope this makes sense⌠
Another good video
The English Mechanic:
Good video.
Question: At 0.52 it says that the DPF continuously oxidizes the (carbon?) particles, is there enough oxygen in the exhaust to do this? Guessing it`s not free oxygen so does this oxygen come from the NOx gases? Or am I asking seriously silly questions? ( YES is a valid answer here).Hi Franglais, no such thing as a silly questionâŚ
Passive regeneration takes place as you are driving along under normal driving cycles, requires no extra inputs from the driver or engine and no extra fuel is injected into the exhaust system.(this is the best possible outcome as all it requires is the engine to be used as intended)
An active regeneration takes place when the engines/aftertreatment computers decides that certain pre-calibrated parameters have been met. The computers will then start an active regeneration and extra fuel will injected into the exhaust system to create the temperature required to clean the DPF.
So the short answer is⌠there is always enough of everything (element) in the exhaust gases to complete passive regeneration, the heat is the only thing that needs to be createdâŚ(by engine load)
Hope this makes senseâŚ
Another good video
Thanks for the that.
That 2nd link seems to show that the Carbon (soot) deposits are combining with one of the Oxygen atoms in the Nitrogen-Dioxide present in the exhaust, which will convert the NO2 into NO1, hence the need for the 2nd stage of adding Ammonia to convert the Noxes (NO1 and NO2) into water and CO2. Yep, so that reaction would need a certain temperature before taking effect? and in light operating conditions it`ll firstly recirculate the exhaust gases to increase temps, and if still too cool will use a â7th injectorâ to boost temps to what is necessary. OK, thanks again for your answers.
Thanks for the that.
That 2nd link seems to show that the Carbon (soot) deposits are combining with one of the Oxygen atoms in the Nitrogen-Dioxide present in the exhaust, which will convert the NO2 into NO1, hence the need for the 2nd stage of adding Ammonia to convert the Noxes (NO1 and NO2) into water and CO2. Yep, so that reaction would need a certain temperature before taking effect? and in light operating conditions it`ll firstly recirculate the exhaust gases to increase temps, and if still too cool will use a â7th injectorâ to boost temps to what is necessary. OK, thanks again for your answers.
The DPF and SCR do require being within certain temperature ranges to be efficient. The temperature will differ between manufactures but the DPF will need to be somewhere around 600f - 800f for passive regeneration and around 800f - 1200f for active regeneration. The SCR will need to be around 600f - 800f to be at its most efficient but like i said it will depend on the manufacture.
EGR is mainly used to lower in cylinder combustion temperature as this helps to reduce nox before it leaves the engine.
The video is a really good overview of how the individual systems work but just be aware that the sequence that each operation happens can be different i.e. the EGR system can be closed and only the intake is restricted or the intake and exhaust can be restricted and the EGR closed. The engine/aftertreatment computers will make calculation and decide what the best approach is to keep the system working at its most efficient.
When a vehicle has a low duty cycle (like in town delivery) you will most likely have more active regeneration and when the vehicle is mostly highway (and loaded) you should be mostly in passive regeneration.
I probably make it sound more complicated than it isâŚ