DPF regeneration oil burning smell. B200d

[JWS1]

Whilst searching web for an issue with my new B200d (now done less than 1000 miles), I found a thread by KNG describing similar issue but can’t now find it, search simply says can’t find member KNG. Anyway, yesterday I pulled up at destination after just 8-mile drive and “serious” overheat issues indicated by very strong oil burning smell, and under bonnet cooling fans running flat out for several mins after stopping engine. Worrying at the time, but it’s looking like I probably stopped in the middle of a DPF regeneration cycle. I could of saved the time and worry if this was made clear at the time of purchase or at least in the documentation.

 

[Srdl]

Yes it can be worrying when it first happens but nothing to worry about and, despite what others may say, no problem stopping the car part way through the regen and it will simply start it again when it wants to. The only real issue to be aware of is that, if you do a lot of short journeys where the engine does not properly get up to temperature, you may start to have problems with the DPF. The dealer should have discussed that with you as part of the purchase but they rarely do for fear of losing a sale.

Welcome to the forum.

 

[Blobcat]

Hello and welcome

Clouds of smoke and a horrible smell is normal DPF regeneration burn off. Not sure why they don’t describe it as such in the manual... perhaps they don’t wish to put owners off

 

[malcolm E53 AMG]

Welcome to the forum and the world of DPF regeneration.

You are quite right there should be more about DPF forced regeneration in the handbook but in mitigation it is an automatic system. During a regeneration yes there is be a tidal wave of hot air coming from under the car and the fans especially on a hot day will run at full speed but there shouldn’t be any smoke coming from under the car if there is you may have a small oil leak getting onto the exhaust.

From what you’ve described with your car everything seems normal

 

[jp williams]

Hello and welcome

Clouds of smoke and a horrible smell is normal DPF regeneration burn off. Not sure why they don’t describe it as such in the manual... perhaps they don’t wish to put owners off

A Regeneration warning light on the dash with an appropriate text in the Handbook would have been more than useful,but as has been implied would have led to a significant drop in sales.
Manufacturers have been underhand and such practices will impact future sales.

 

[JWS1]

Thanks for comments, I understand it a lot better now, though of course (with my engineering hat on) don't necessarily agree with the technology and the effectivelly hiding it from the customer, although it would not have stopped me buying it as otherwise, a great car.

 

[Dean Fletcher]

Thanks for comments, I understand it a lot better now, though of course (with my engineering hat on) don't necessarily agree with the technology and the effectivelly hiding it from the customer, although it would not have stopped me buying it as otherwise, a great car.

All normal as far as I can tell. I was once told best way to start a regen was to stick in cruise control at around 65mph and let it go for 20 to 30 minutes. But make sure it's up to temp first and you have over a quarter tank fuel.
And welcome to the forum

 

[malcolm E53 AMG]

A forced regeneration only takes place every 300/400 miles or so if the car sees mainly short journeys otherwise passive cleaning of the DPF takes place where the engine and exhaust generally see normal operating temperatures on a consistent basis ie, fast A road/motorway driving. I find the MB system works very well and not many problems noted on her as opposed to some manufacturers

 

[dannyfiveforty]

Do you find the cars throttle response is lumpy/hesitant/inconsistent whilst the car is regenerating? That’s how I know mine is doing one.

 

[malcolm E53 AMG]

Do you find the cars throttle response is lumpy/hesitant/inconsistent whilst the car is regenerating? That’s how I know mine is doing one.

My OM642 engine revs at 800 at idle and gives a sharper exhaust rasp in fact I wish the car was as nice to drive all the time changes are smoother and no drop off in throttle response - how they all differ obviously

 

[Srdl]

My OM642 engine revs at 800 at idle and gives a sharper exhaust rasp in fact I wish the car was as nice to drive all the time changes are smoother and no drop off in throttle response - how they all differ obviously

My OM642 was the same - sounded good and just “felt” a better drive, presumably down to all the extra fuel it was burning!

 

[rf065]

My w205 appears to regenerate without any outwards sign at all, no smoke, noise or any other difference in the way it runs.
Only way I can tell it's happened is exiting the car and putting a foot on the ground, you can feel the excess heat from under the car, other than that you would never know.

 

[dannyfiveforty]

My w205 appears to regenerate without any outwards sign at all, no smoke, noise or any other difference in the way it runs.
Only way I can tell it's happened is exiting the car and putting a foot on the ground, you can feel the excess heat from under the car, other than that you would never know.

What year/model is yours?

Thanks

 

[rf065]

What year/model is yours?

Thanks

C250 2016

 

[Capra]

My OM642 engine revs at 800 at idle and gives a sharper exhaust rasp in fact I wish the car was as nice to drive all the time changes are smoother and no drop off in throttle response - how they all differ obviously

I've never heard the sound of the diesel engine exhaust note be likened to a rasp before.

 

[dannyfiveforty]

I've never heard the sound of the diesel engine exhaust note be likened to a rasp before.

My bluetec has no sound difference at all. My previous 2008 300C srt would would have a ‘deeper’ sound, but would drive absolutely no different than when it wasn’t regenning.. frustrating really

 

[400ixl]

You are quite right there should be more about DPF forced regeneration in the handbook but in mitigation it is an automatic system.

A forced regeneration is when you plug it into a diagnostic machine and force it to do an immediate regen. That isn't something that would go into any owners manual as it is a very rare event and driven by the dealership diagnosing an issue which would have thrown the Engine Management warning light. That even is in the manual and tells you to take it to a service centre.

As the automatic regeneration is not something the owner interacts with, and should be pretty much invisible to them, I can't see why you would want it described in the manual. It will just cause more confusion than anything with people trying to see if they can spot it happening and getting concerned its not when they can't.

Now, what perhaps should be in the manual (if its not) is a warning that lots of sub 3 mile journeys with no longer journeys within a 300 mile period will potentially mean that regens do not happen and could cause problems. Car dealers should then be compelled to check the driving patterns of the potential owners to ensure this is not going to be a concern and if so, point them to other forms of power, be it petrol, electric etc.

 

[Dean Fletcher]

I work 9 miles away from where I leave i do that trip and back 5 to 6 times a week. Occasionally I'll go to Carlisle which is 20 miles away usually 2 one times a month. Iv never had any issues with dpf regens. I even had a eml on for a month while investigating a inlet manifold issue. I have never seen, felt and smelt the regen happening but I know it does it as I had it checked by my indy and main deal on services and came back as regen operation normal. I'm glad I cant see it happening.

 

[malcolm E53 AMG]

A forced regeneration is when you plug it into a diagnostic machine and force it to do an immediate regen. That isn't something that would go into any owners manual as it is a very rare event and driven by the dealership diagnosing an issue which would have thrown the Engine Management warning light. That even is in the manual and tells you to take it to a service centre.

As the automatic regeneration is not something the owner interacts with, and should be pretty much invisible to them, I can't see why you would want it described in the manual. It will just cause more confusion than anything with people trying to see if they can spot it happening and getting concerned its not when they can't.

Now, what perhaps should be in the manual (if its not) is a warning that lots of sub 3 mile journeys with no longer journeys within a 300 mile period will potentially mean that regens do not happen and could cause problems. Car dealers should then be compelled to check the driving patterns of the potential owners to ensure this is not going to be a concern and if so, point them to other forms of power, be it petrol, electric etc.

Some interesting points made:

The DPF as we all know filters soot from exhaust gas over a period of miles and as said short journeys don’t allow enough heat to build up in the exhaust to burn this off. When the pressure sensors fore and aft of the DPF unit detect that the unit is full the ECU forces a regeneration by injecting diesel into the exhaust to burn off the soot. It’s all a matter of terminology admittedly and yes a dealer can hook the car up to STAR and do this.

As far as what’s said in the manual is concerned a modern diesel fitted with a DPF can be quite alarming to some, the noise created (burning fuel in the exhaust) and heat generated under the vehicle are quite an experience especially with the V6 lump