Soot patch on driveway...Please help
 

Hello,

First, I have great respect for everyone who makes this discussion forum what it is - thank you all.

My car is a 1985 300d and I have been getting a soot patch on the driveway recently as well. The car starts immediately even when it's 20 degrees f outside, and the glow plugs are new and injectors were recenlty replaced with Bosch rebuilds. (now that I think of it, this did begin sometime after the injectors were replaced). The car burns no oil between 3k changes and doesn't smoke and fuel mileage hasn't changed. Also, this started before I began messing with the ALDA.
The soot comes out of the exhaust about 1-2 minutes after starting the car, it idles fine, hmmmmmm..... Could be leaky valve seals Ifso, wouldn't it smoke initially? This is leaving patches on the concrete and they aint' easy to clean!
Thanks for any help in advance.
Happy benz'n. Adam:confused:

Adamb,

Paint the driveway black. LOL

P E H

I could be wrong, but I think the soot patch is normal. My 300D leaves one everywhere it goes. Kinda like a little Benz calling card ;)

Did the weather get colder after you installed the new injectors? Possibly a cold cylinder head + cool moist exhaust + imcomplete combustion from cold cylinder head = wet sooty exhaust that shows up on your driveway. Could try letting the glow plugs work 10-20 seconds after the light goes out and then tire...

Mine always leaves a patch :D

The re-designed glow plug relay keeps them working after the car starts, up to a minute I think. This makes the car run better when it is really cold. I don't think the '85 has that design. The new kit with glow plugs and relay was around $100 and easy to install when I used one on my daughter's 240D. I had to interpret the directions, but no one writes these days. At that time (two years ago) you couldn't buy the extra glow plug for the 5 cylinders; it was only available in the kit. I called Boosh tech and they were extremely helpful, but they couldn't figure out why the plugs were not available individually. I hope they are now.
But I would think that this improved system would affect this situation. That said, I just park my own three diesels at random on the driveway and in a couple more months there will be no need to paint it.

Good luck, Dan Stadt

Sounds like everyone is resigned to live with the soot stains. I don't have one where I park my 240D. My car requires no throttle to start, and I try not to rev it up stone cold. I wonder if that might make a difference in blowing out the soot. If you could wait until you begin to roll before developing higher RPM, perhaps the soot would be spread out over a bigger area and not be noticable (or better yet out in the street).

My $.02 worth.

All my diesels do this, always have. I consider it normal. RT

This discussion reminds me of a conversation I had back in the early 70's with a truck driver. He was a regular delivery driver to our small store and I noticed that he had the exhuast on his smoky old diesel truck set up under the truck vs. the usual set up to blow exhaust out and behind the cab. He said it wa changed after his company started getting ticketed by the State Troopers that had begun using some kind of guns to measure the soot output of the fumes. With it blowing under the truck/trailor they couldn't get a line to pass out thier tickets.
So the MB exhausts are mounted low, and angled straight down. Voila, the early morning soot with warmup will run into our driveways and leave a black area. Maybe we should just drive them away a bit sooner?:D Or better yet alter the exhaust pipe? :eek:
We are just driving these old diesels. They all get a little sooty.

Hey, we could always put dual stacks on our lil' diesels!! ;)

Yes, I'm kidding :)

I can not explain how happy I am to read all of your responses - THANK YOU ALL!! I was prepared to dig deap into my pocket to fix this thing if I got different responses. Thanks again, this site is the best one on the net.
Adam:D

Heck there is a real easy fix for that... Do not park in the drive way..

Ken

My 240D leaves a soot mark only if l lead-foot it for initial take off (if you can call it that). If I give the engine just enough revs to set the car in motion, I don't get a mark. I would rather creep out when the car is cold than be trying to clean up those marks constantly.

Hope this helps.

It's not leaving a soot mark.
IT'S MARKING IT'S TERRITORY.

*G*

Dave

240 versus 300 soot marks
 

I just noticed this phenomonen this last week as the new 300 leaves soot marks and the 240 never has...
The 300 starts better in the cold too.

Wonder if that is just the Big Dog marking it's territory to ensure the little dog stays in line?

:D