soot around gas pedal, and on dash - PeachParts Mercedes-Benz Forum

blankpro · #1 11-17-2006, 11:49 AM

I have a 1985 W126 300SD and I am noticing soot appearing from time to time on my dash, near the footwell on the driver's side etc. Should I be concerned? Is there a solution? Is there a problem?

patbob · #2 11-17-2006, 12:39 PM

Are you sure it's soot and not just dirt?

I don't know the w126 at all, but soot is serious no matter the car. It means incomplete combustion products from somewhere are getting into the cabin, and probably a lot of them (or a little from a real sooty source). That's serious. Unless you have a combusion-powered block heater, the only thing burning should be fuel, which would indicate you have an exhaust leak getting into the cabin. You could also have something else burning that isn't supposed to be doing so (e.g. something under the dash).. also pretty serious since it is continuing.

If it were my D, I'd drive my gasser while I dropped the under dash panel on the drivers side to figure out its source and how its getting into the cabin.

Dirt, on the other hand, probably isn't as much of a concern and might be coming in from the ventilation system or through the firewall where the pedal linkage goes through.

I'm kind of coming up blank on how to definatively test to see which it is.

blankpro · #3 11-17-2006, 12:42 PM

if it's dirt, then how do I stop it?

F18 · #4 11-17-2006, 12:45 PM

Thats odd....are you sure its soot? Could it be road dust coming through a bad door seal or bad wiring rubber seal in the fire wall/bulk head? Do you smell any diesel exhaust fumes?
The Exhaust manifold and Header pipe come down from the right side of the engine (passenger side)....?....unless your from the UK and driving on the right I don't know how even a loose exhaust fitting or hole could spew soot so it gets it on the left side of the dash board and interior of the well.????
Just double check to make sure all wire harnesses and the speedo cable are properly sealed coming through the bulkhead from the engine compartment.
Also check your exhaust system for leaks especially with winter coming....you don't want Carbon Monoxide poisoning>
May be someone else has had a similar problem on this board.....I never had a problem like that on the 84 or 87SDs

Plenty of soot on their bumpers though!

blankpro · #5 11-17-2006, 12:55 PM

Soot is evenly distrib on the dask (not visible but when I run my finger along it it turns dark). I see particles around the gas pedal, and around the heater vent at my feet.

vstech · #6 11-17-2006, 12:58 PM

most likely, it is insulation breaking down inside the ductwork. my two drivers do the same thing. it appears from the defroster ductwork.

John

tobybul · #7 11-17-2006, 01:03 PM

Quote:

Originally Posted by vstech

most likely, it is insulation breaking down inside the ductwork. my two drivers do the same thing. it appears from the defroster ductwork.

John

I think John is right about coming from the defrost mode but am thinking maybe more coming from the hood pad insulation coming off and getting into the ventilation air intake. My hood pad is due for a change real badly.

blankpro · #8 11-17-2006, 01:06 PM

Quote:

Originally Posted by vstech

most likely, it is insulation breaking down inside the ductwork. my two drivers do the same thing. it appears from the defroster ductwork.

John

This makes sense, since it does not appear to be my hood pad (it's new). How do you fix this? Ordo you?

vstech · #9 11-17-2006, 01:27 PM

Quote:

Originally Posted by blankpro

This makes sense, since it does not appear to be my hood pad (it's new). How do you fix this? Ordo you?

I have just been keeping it clean... I don't really feel like removing the dash and chasing down where it's breaking down...
John
hmm.
if your hood pad is new, the old one most likely fell apart, tons of debris could be accumulated on the a/c coil or heat core. so that could indeed be what it is from.
both mine are totally falling apart, so that could be it.
John

winmutt · #10 11-17-2006, 02:04 PM

insulation in the duct work? I think its more likely to be just crap burning off the heater coils.

vstech · #11 11-17-2006, 02:37 PM

Quote:

Originally Posted by winmutt

insulation in the duct work? I think its more likely to be just crap burning off the heater coils.

I was thinking of the foam that is surrounding all the duct joints and padding in various places deteriorating and getting sucked into the ductwork and blown out at the defrost vents.
John

winmutt · #12 11-17-2006, 02:48 PM

Quote:

Originally Posted by vstech

I was thinking of the foam that is surrounding all the duct joints and padding in various places deteriorating and getting sucked into the ductwork and blown out at the defrost vents.
John

I can see that. I have the same problem on my TD

blankpro · #13 11-17-2006, 03:39 PM

Quote:

Originally Posted by winmutt

I can see that. I have the same problem on my TD

Yes, come to think about it, the particles are a little too big to be soot.

How can i get in there and clean them out?>

vstech · #14 11-17-2006, 03:47 PM

Quote:

Originally Posted by blankpro

Yes, come to think about it, the particles are a little too big to be soot.

How can i get in there and clean them out?>

um,... search for dash removal. there are a few threads about it MAJOR PIA!
John

tobybul · #15 11-17-2006, 07:50 PM

Another way is to seal the passage ways (ducts). No different than when contractors clean your heating ducts at home, they spray a sealant after to keep any loose particles from being carried in the airstream. Now this sounds like a good solution - BUT - I do not know of any tool/device to reach in there and do the spraying. PLUS, gotta be careful that any sealant sprayed does not go to the actuators as it may affect their operation.

Just a thought...

Another thought is using a leaf blower and somehow blow into the intake hoping that it'll blow that stuff out.... or use a shopvac and suck it out from the defrost outlets....or from the intake.... not sure exactly where the intake is though. I know the grilles outside the windshield are part of it but thats got a drain somewhere so rain water does not go right in.