black oil gunk in cavity and on top of blower motor...

[Darragh1]

E250 OM651 2010 Estate
I have the car nearly a year.
When I first had the car there was bad feet smell which I neutralized with a can of Mannol (shave foam type) aircon cleaner.
I have a sensitive nose so I am glad that quite recently a mystery diesel leak has kindly manifested itself and is due for fixing asap.
It has had three injectors replaced by the previous owner. I mention this in case it relates to what I found today.
I wanted to check my battery so I removed the box on top of it. I reached in through the air intake and down towards the blower motor and there was a considerable film layer of what smells like oil.
Is this normal for a 10 year old OM651 in need of some tlc?
Does it relate to diesel leaks past an present over the years?
What is the remediation? Is there a Magic product that not only neutralizes bacterial odours but dissolves oily residues etc? Will this black filth have infiltrated into all the other air ducts and vents including as far as the flor vents in the rear footwells?
Thanks for listening.
D.

 

[Darragh1]

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[Larkone]

10 years of sucking diesel fumes as you drive about is probably the answer. I think your filter is after the fan which would also explain this. My CLS (diesel) fan is clean because the filter is before the fan.

 

[markjay]

Start by replacing both cabin filters... there should be another one under the gloves compartment. They are due replacement every 2 years, BTW.

 

[MrGreedy]

I've got a 2011 w212 and I thought I only had a cabin filter after the fan accessible from the passenger foot well.

In the photos attached by the OP, it looks like there is a filter before the fan, that can be seen through the two rectangular holes once the box above the battery is removed.

Should there be a pre fan filter on this model? I don't understand how that filter would be accessed to change it?

 

[Petrol Pete]

I am not familiar with the cabin filtration on this particular car but having a filter after but not before the fan would be a strange way of doing things.

The other way around maybe, a filter before the fan and none after, or two filters ? yes ...But none before and one after the fan. Makes not a lot of sense. . Sucking dirty air into the fan and all the ducts only to filter it on its way into the cabin ....

It might just be the way it is on this car . Someone on here will know.

 

[W1ghty]

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Does the box you removed from on top of the battery contain the pollen filter (mine does )

 

[MrGreedy]

Does the box you removed from on top of the battery contain the pollen filter (mine does )

I know this question wasn't directed at me, but my box above the battery has no filter for my w212. Which also seems strange.


So I've looked at the online Merc parts catalogue, and with the various exploded views of all the air ducting etc, and the only filter I can find is the post-fan one that pushes up into the dash, under/behind the glove box accessible from the passenger foot well.

 

[mioba]

Looks normal to be fair for a 10 year old car and doesnt look like alot, replace the filters with new genuine, sometimes aftermarket filters dont seal so well.

If you can get the housing out then a wash with washing liquid and dry will do. Otherwise carb cleaner on a tissue to wipe it down.

Keep up with with the great TLC and you will be very happy soon.

 

[Petrol Pete]

It might 'look' normal but it make's little sense. Other W212 owners on here say no filter before the fan , OK , so be it. But any oily residue that might be in the engine compartment maybe due to a fault or just 'how the car is' will invariably coat the whole inner workings of the HVAC system .

TBH I replaced the cabin filter on the wife's Zafira not long ago and I think that one is 'post' intake fan. i:e no filtration before the fan housing intake.

 

[mioba]

It might 'look' normal but it make's little sense. Other W212 owners on here say no filter before the fan , OK , so be it. But any oily residue that might be in the engine compartment maybe due to a fault or just 'how the car is' will invariably coat the whole inner workings of the HVAC system .

TBH I replaced the cabin filter on the wife's Zafira not long ago and I think that one is 'post' intake fan. i:e no filtration before the fan housing intake.

I was referring to the residue, which looks more like condensed dirt than an oily film

 

[Darragh1]

Hi,
My car has a passenger side pollen filter under the dash accessible via the footwell. I replaced it recently. I think the function of the box is for the recirculation function. I think that which seems like a filter above where the fan in the cavity leads directly to the passenger side vent. I'll further investigate that as it does wobble a bit in an accordian kind of way and maybe should be connected up somewhere.
The gunk does smell and feel oily diesley.
The cabin filter is new. I just got a fright because I wasn't expecting the gunk. This is my first diesel.
Before I replaced the pollen filter I used mannol aircon system cleaner sprayed foam into the vents and up high via a long flexi tube into the ducting. I recall before spraying, when I removed the pollen filter, that the ducting as far as i could feel had some dirt but was quite clean overall.
I know what a pollen filter does and this question might sound naive but does the pollen filter trap the gunk before it enters the ducting which leads to the vents? Is that the idea? Ergo, most of the dirt would be trapped on the way to the pollen filter?? So the rest of the system ducting might be clean(ish)?
Thankles,
D.

 

[MrGreedy]

I'm not sure if the heater system is 'handed' left or right, but these are the photos courtesy of 7zap (working at the moment, so thank you 7zap)

There is no filter in the engine compartment air intake/cover that sits above the battery (50 in first image).
The cover above the battery (50) connects to some ducting (100) also in the first image.

In the second image, the recirc flap and housing connects to the rear of the ducting mentioned above (100, first image).
Then the recirc flat bolts onto the top of a/c housing (10 in second photo).

You can see that the air then is fan pumped firstly through the pollen filter and then past the evaporator for the aircon (430) to dry the air, the heat exchanger (400, provides heat from warm coolant), and then the electric booster heater (300, used when engine is cold).

From there, it connects to the air conditioner case/housing (20 in second photo), where it is diverted to the required vents/cabin sections.

So via the recirc flap/housing, the air either enters from the engine bay and to the pollen filter, or the engine bay intake is bypassed and recirculated air also passes through the pollen filter via the same route.

 

[MrGreedy]

Hi,
My car has a passenger side pollen filter under the dash accessible via the footwell. I replaced it recently. I think the function of the box is for the recirculation function. I think that which seems like a filter above where the fan in the cavity leads directly to the passenger side vent. I'll further investigate that as it does wobble a bit in an accordian kind of way and maybe should be connected up somewhere.
The gunk does smell and feel oily diesley.
The cabin filter is new. I just got a fright because I wasn't expecting the gunk. This is my first diesel.
Before I replaced the pollen filter I used mannol aircon system cleaner sprayed foam into the vents and up high via a long flexi tube into the ducting. I recall before spraying, when I removed the pollen filter, that the ducting as far as i could feel had some dirt but was quite clean overall.
I know what a pollen filter does and this question might sound naive but does the pollen filter trap the gunk before it enters the ducting which leads to the vents? Is that the idea? Ergo, most of the dirt would be trapped on the way to the pollen filter?? So the rest of the system ducting might be clean(ish)?
Thankles,
D.

It is possible the 'shaving foam' style decontamination has stripped/collected a lot of the fine engine, diesel and road grime 'dust' that was coating the inside of the ducting, and then slumped or found its way down into the bottom of the fan.
Is it possible if you had used an aerosol decontamination 'bomb' that if you were then wiping inside the ducting you would just find dry, dusty contamination?

Do you have any of the aircon foam left? What happens if you spray it on to e.g. an old baking tray and leave it for a few days? Does it dry without trace or residue, or is there anything left?
Might be worth a test?

 

[Darragh1]

Thank you MrGreedy for those diagrams of the ducting.
I posted a new topic bit which belongs here- i have another can of shavefoam aircon cleaner which i intend using-possibly sprayed directly into the hole into which the evaporator temperature sensor inserts.

Quick question evap clog??? | General Discussion

Hi 2010 E250 S212 wdd2122032 om651 I intend running some mannol shave foam style cleaner with the long hose attachment through the aircon ducts and evaporator. https://www.mannol.de/products/car-care-products/interior-care-products/mannol-air-conditioner-cleaner Is there a way of checking if...

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