Author Topic: Black Stuff From Exhaust  (Read 497 times)

250SLFranco

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Black Stuff From Exhaust
« on: June 13, 2019, 22:44:00 »

When I start my 250SL up after a night in the garage, the garage floor and the cabinet facing the exhaust get splatterings of black stuff......
What is it and how can I stop it from happening?  Is it an indication of a bigger problem I should address?

250SL Franco

Mike Hughes

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Re: Black Stuff From Exhaust
« Reply #1 on: June 13, 2019, 23:48:22 »
The engine may be running a bit rich, coating the inside of the exhaust pipes with black soot (carbon).  Easily seen if you look at your tail pipes. 

So now we have to go back to high school chemistry class:  When you combine a hydrocarbon with oxygen you should get carbon dioxide and water.  If you are running rich, you are going to get carbon, carbon dioxide and water.   

When you first start your car, the exhaust system is cold, so the water in your exhaust condenses from steam to a liquid state and the water droplets can travel all the way out to the end of the cold tailpipes, collecting carbon soot from the interior walls along the way.  The result is the spray of sooty black water droplets on the garage floor and cabinet behind the tailpipes ( and the shins of your khaki's if you happen to walk around behind your car when it is idling!). 
- Mike Hughes  -ô¿ô-
  1966 230SL Auto P/S
  Havana Brown (408)
  Light Beige (181)
  Cream M-B Tex (121)

Paul & Dolly

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Re: Black Stuff From Exhaust
« Reply #2 on: June 14, 2019, 10:57:11 »
.....and make sure your wife is not wearing white trousers & standing behind your Pagoda when you start it !

Don't ask

Paul
Paul (located in Cardiff - Wales - UK)
1967 Early 250 SL (Auto) White
Kia Sorento CRDI XS
Mitsubishi i Car
1936 Alvis Firebird (Gone............)

Pawel66

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Re: Black Stuff From Exhaust
« Reply #3 on: June 14, 2019, 14:33:00 »
A piece of cardboard o n the floor helps.
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

MikeL43

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Re: Black Stuff From Exhaust
« Reply #4 on: June 17, 2019, 20:30:55 »
I have experienced the same thing with my 250 SL and still have a pair of trousers to prove it.  I have reached the same conclusion as Mike Hughes, that is that this is normal for a car with 50 year old technology.  Otherwise my car runs great and I doubt it could be improved upon so I'll just back my car out of the garage as soon as I start it and let the "black stuff" fly.   

Paul & Dolly

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Re: Black Stuff From Exhaust
« Reply #5 on: June 17, 2019, 21:41:27 »
Or you could fit these tailpipes

A116 492 0514

They work well and deflect the exhaust downwards

Paul
Paul (located in Cardiff - Wales - UK)
1967 Early 250 SL (Auto) White
Kia Sorento CRDI XS
Mitsubishi i Car
1936 Alvis Firebird (Gone............)

su8pack1

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Re: Black Stuff From Exhaust
« Reply #6 on: June 18, 2019, 01:54:42 »
I had that problem too until I put in new injectors, and had the injection pump rebuilt.
1969 280SL
1984 300CD
1987 190E 2.6
1988 190D 2.5

FresnoBob

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Re: Black Stuff From Exhaust
« Reply #7 on: June 19, 2019, 17:40:46 »
I too wish I could reduce the amount of black soot that shoots out when the car is started cold.  I'm still struggling with my WRD, starting aids and cold idle...
1966 230 SL Euro Auto
2017 AMG C43 Cabriolet

kampala

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Re: Black Stuff From Exhaust
« Reply #8 on: June 19, 2019, 18:25:07 »
Kent (mercedessource) has done a couple of videos regarding this issue.  The links have been discussed on our forum prior.   Not all agree with everything Kent says about Mercedes, especially Pagodas but worth a look.

https://www.youtube.com/watch?v=PLedjKWbU5w
https://www.youtube.com/watch?v=nmkiBz65Wjs&list=PLtRKk64pu2wr2hetff0CXA-nDXVfPqfQ5&index=6&t=0s

There are more videos - just posted two.

I believe a couple of folks on our forum have taken his suggestions about the injectors - would be interesting to know if they were able to quantify a difference. 
Oz
Paris France & California
250sl - later - manual
280sl - 1971 - Auto - Limited Slip Diff.

Paul & Dolly

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Re: Black Stuff From Exhaust
« Reply #9 on: June 19, 2019, 21:48:01 »
I replaced all my injectors 2 years ago before our Irish trip, it made no difference to sooty start up or mpg,but car runs fine, so I am happy,that's why I used the deflected exhaust tips..
Now we have just arrived in Germany for Pontoon Rallye in Hameln.

Paul and Dolly
Paul (located in Cardiff - Wales - UK)
1967 Early 250 SL (Auto) White
Kia Sorento CRDI XS
Mitsubishi i Car
1936 Alvis Firebird (Gone............)