1990 300D,,,,just had my first oil change done since purchase,,,checked oil after driving about 50 miles and already black on dip stick,,,problem or not????

2nd question,,,,AC blows ice cold,,,but just today it stopped blowing from 2 middle vents,,,whats the problem??

Thanks in advance

Anything past 1985 or not a 123 and I am just guessing...
but usually the center vents are operated by one vacuum operated pod.
So maybe a vacuum leak at at that point... or in the diaphram....

Black oil is perfectly normal. No matter how well it is drained, there is always enough residual oil to blacken the new oil.

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Keep everything as simple as possible-but no simpler--Albert Einstein

The black oil is soot, and this is totatly normal for the diesel engine.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

The center vents on a W123 and a W116 are fresh air only...and they only work when controls are set to ambiant temp.....which means no heat or cool...

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

No kidding. Jokes aside, I let my oil drain out overnight and put in a fresh filter the next morning. 2 mins after i start it up, it will be black as coal so 50 miles is meaningless as far as that goes. I assure you that I am using Mobil1 Truck & SUV oil which is lighter than many non synthetic oils that you are probably using.

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01 Ford Excursion Powerstroke
99 E300 Turbodiesel
91 Vette with 383 motor
05 Polaris Sportsman 800 EFI
06 Polaris Sportsman 500 EFI
03 SeaDoo GTX SC Red
03 SeaDoo GTX SC Yellow
04 Tailgator 21 ft Toy Hauler
11 Harley Davidson 883 SuperLow

black oil is unavoidable in a diesel.

the onlly diesel i have bought new is my 03 dodge. i have 37000 miles on it and the oil is not yet black but it is getting darker all the time.

all my mercedes diesels run the oil black. if newly rebuilt they are clean for a while but in 10000 or so they are black again.

on my 123s the center vents run with the ac, not fresh air all the time.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I have noted the same thing on my 03 Duramax. Everybody told me a diesel would have black oil, but the truck didn't. Then I bought the Benz and knew what everybody meant. The 'max is getting there, though.

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Keep everything as simple as possible-but no simpler--Albert Einstein

I've put 1000 miles on my engine since I changed the oil, and it's not black. Of course, I burn B100.

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'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg

Hmm, I have never seen my oil stay that clean when burning bio or veggie. You must have an exceptionally clean engine and no blowby.

__________________
Keep everything as simple as possible-but no simpler--Albert Einstein

It's darker, but still translucent, like a gasser.

__________________
'83 240D with 617.952 and 2.88
'01 VW Beetle TDI
'05 Jeep Liberty CRD
'89 Toyota 4x4, needs 2L-T
'78 280Z with L28ET - 12.86@110
Oil Burner Kartel #35

http://i16.photobucket.com/albums/b1...oD/bioclip.jpg