Swirl Flap issues on low mileage W205

Page may contain affiliate links. Please see terms for details.

wongl

MB Enthusiast
Joined
May 29, 2005
Messages
1,418
Location
Surrey and Hong Kong
Car
A180CDI, B200d, C300h, SLK250
2016 W205 C300h low mileage, circa 4,500 miles with swirl flap error. Three times now, each time in December. First time Dec 2018, then Dec 2019, and then last week Dec 2020.

First two times checked and error code cleared by Mercedes Mobilo - claimed that the Swirl Flaps were operating normally under test using Xentry. Mentioned this to the dealership during service but was told to bring the car to them without the error being cleared by Mercedes Mobilo. So this year I got the car in with the annual service/MOT. Dealership cleared the error to get it through MOT. But when I collected the car it was back on.

The dealer tried clearing the code again but now will not clear. Keeping car until after the holidays for further diagnostic. They think it could be due to carbon issue due to the low mileage - unsure if this will be covered by the Mercedes extended warranty!
 
Whats the total mileage ? youve probably heard many people say supermarket fuel is the same as the premium fuel ,I suspect you inlet manifolds will say different , short journeys and cheap fuel will cost dearly in the long run.
If it was my car I`d fill up on Shell V-Power and go on a 200-300 mile motorway drive , drive it as hard and fast as the law allows , if you are lucky it may cure it , if not it may well be a strip down job .
 
Whats the total mileage ? youve probably heard many people say supermarket fuel is the same as the premium fuel ,I suspect you inlet manifolds will say different , short journeys and cheap fuel will cost dearly in the long run.
If it was my car I`d fill up on Shell V-Power and go on a 200-300 mile motorway drive , drive it as hard and fast as the law allows , if you are lucky it may cure it , if not it may well be a strip down job .
Yes, I use supermarket fuel (Tesco's) but with Redex at every fillup. This car is low mileage at circa 4,500, used mainly for motorway runs only as the little A-Classes are better suited for London traffic.

I have been stuck abroad and the car has only done 82 miles between its service in Dec 2019 and its service this Dec. Car now stuck at main dealership, so no chance to take it down the motorway for a blash.
 
Update from the local MB dealership who serviced the car on 23 Dec 2020. Apparently, they have finally got round to looking into the problem and diagnosed that it will need a new 'manifold'. Fortunately, it looks like this will be covered by the extended MB warranty that we purchased at a cost of £850 towards the end of the original 3-year factory warranty (thus avoiding any gaps between the two warranties).

The bad news is that they will not be able to commence the work until next week. We purchased the extended MB warranty because we suspected the complexity of the C300h could be tricky to diagnose and fix by an indie but really surprised that it needed a new manifold at only 4,500 miles with an FSH from MB.
 
Whats the total mileage ? youve probably heard many people say supermarket fuel is the same as the premium fuel ,I suspect you inlet manifolds will say different , short journeys and cheap fuel will cost dearly in the long run.
If it was my car I`d fill up on Shell V-Power and go on a 200-300 mile motorway drive , drive it as hard and fast as the law allows , if you are lucky it may cure it , if not it may well be a strip down job .


The real culprit here is the egr devil valve...no doubt working like a jack hammer to reduce NOx but **** up alot of other things .
 
The real culprit here is the egr devil valve...no doubt working like a jack hammer to reduce NOx but **** up alot of other things .
My limited knowledge on the subject is that the swirl flaps are on the fresh air inlet and controlled by a plastic rod that is prone to breaking on some Mercedes. The strange thing is that the mechanism is visibly not broken and according to the Mobilo/RAC engineer who attended, the swirl flaps passed the calibration test on his Star Diagnostic and he can visibly see it moving during the calibration. Clearing the error code seems to work for a few tens of miles before the error code returns.

I suspect a position sensor being faulty, but if MB wants to replace the whole manifold under the extended warranty, I am not going to argue with them. Just glad that they haven't simply cleared the error code and send me on my way this time. I just hope that the new manifold is a newer design that has fixed the weakest link of a plastic rod that is prone to breaking!

Given that this will be replaced under warranty, I don't think that it is due to carbon build up as initially suspected by the service specialist on the 23 Dec based totally on the low mileage of the car!
 
Last edited:
It would be interesting to show a photo of said inlet manifold, just to see if it is "carbon issues" due to low mileage and Tesco fuel.
Can't really see that on a 4,500 miles engine.
 
The EGR issues are usually much higher mileage dieseasles (circa 70k or more typically), where the EGR allows oily slime and carbon to deposit all over the inside of the air intakes. This gunk then restricts the swirl flaps and hence causes various parts of the EGR/intake/swirl flap/motor to break.

I would expect this cause even less for a petrol.

However, that's not to say the EGR valve dumping engine gasses into a no doubt plastic intake manifold hasn't messed things up. Typical poor design now chosen by the majority of manufacturers to reduce build costs (at the expense of maintenance costs that should never exist - but that's often paid by the customer out of their wallet for older cars).
 
I'm surprised considering the motorway use , don't demonise supermarket fuel I've been using it for 30 years and never had a problem , OK I now add my own Cetane booster at a fraction of the price of the con that is premium diesel .


Normal occurring Crankcase oil vapour + sooty diesel exhaust gasses made worse by the egr valve is a super gunker .

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.
 
This was the EGR cooler from my 100,000 mile BMW 320d, the whole EGR circuit was similar. How can this be a good idea ?

egr cooler.jpg
 
It would be interesting to show a photo of said inlet manifold, just to see if it is "carbon issues" due to low mileage and Tesco fuel.
Can't really see that on a 4,500 miles engine.
Car is with the main MB dealership who has NOT been forthcoming with returning my calls, so I am not sure they will cooperate by sending me a photo of the old manifold! But I shall ask as this is a good suggestion. Thanks for the suggestion.
 
I'm surprised considering the motorway use , don't demonise supermarket fuel I've been using it for 30 years and never had a problem , OK I now add my own Cetane booster at a fraction of the price of the con that is premium diesel .


Normal occurring Crankcase oil vapour + sooty diesel exhaust gasses made worse by the egr valve is a super gunker .

To view this content we will need your consent to set third party cookies.
For more detailed information, see our cookies page.
Although I have been using supermarket fuel, and have been doing so for the last twenty years without incidents in all my other Mercedes cars, I have also been dosing each fill-up with Redex.

As a side note, when replacing the pre-heater plug on the W169, my indie had to remove the turbo and commented how unusually clean the turbo was for a W169 with over 120K miles! I put this down as possible due to the Redex?
 
Engines should only breathe cool clean filtered air , period .
Agreed, but unfortunately for proper fuel economy/emission, it is necessary to stave the engine of oxygen from time to time (say during engine overruns), and using the exhaust gas recirculation is a cheap (maybe not so effective) way of doing this.

This is of course 90's technology as we were doing this type of experiment in the lab back then. I am just surprised that manufacturers don't locate the EGR valve in a more accessible location for regular maintenance, and/or have soot traps/filters.
 
Modern car design has a lot to answer for , here's a VAG egr & egr cooler located at the back of the engine above a driveshaft !

5 hr job on ramps to change out usually because the cooler can corrode internally .

Screenshot_20201114-102138_Chrome.jpg

Screenshot_20201114-102121_Chrome.jpg
 
Update on this saga. After over one month, the MB dealership finally replaced the manifold in my car and successfully cleared the EML. No paperwork as yet until the warranty has settled the bill, so no idea of the total cost.

I managed to take some photos of the manifold and the carbon build-up doesn't look too bad.

However, apparently, the B3 service reminder cannot be reset until the car has covered over 100 miles since the previous service last year!
 

Attachments

  • Manifold 1.jpeg
    Manifold 1.jpeg
    114 KB · Views: 13
  • Manifold 2.jpeg
    Manifold 2.jpeg
    105.2 KB · Views: 12
  • Manifold 3.jpeg
    Manifold 3.jpeg
    94.2 KB · Views: 12
Well those flaps look clean to me,just what did cause this problem?
 
Probably a connecting rod .
 

Users who are viewing this thread

Back
Top Bottom