Author Topic: Exhaust emitting black particles at start up (Read 6919 times)

PSB · « **on:** December 03, 2020, 23:18:12 »

Hello,

My 65 230SL runs well, always stars first time but does seem to have excessive fuel consumption.
Today I noticed, by accident , that when starting up and for a few seconds the exhausts emits a significant amount of black particles almost like chimney soot. I put my hand in for 2 seconds front of the exhaust ( not revving ) and the result is in the photo.
After the engine runs a bit I put my hand in front of the exhaust again and no soot , I just get a damp feeling in my hand. If I drive for 15 minutes then restart then I get the soot again. There is no visible smoke but quite a heavy exhaust smell.
What can this be ?

Regards
Pedro

ja17 · « **Reply #1 on:** December 04, 2020, 05:45:18 »

This condition is not unusual on pre-emission automobiles of the past. They ran quite "dirty" on cold start ups. Of coarse, it is hard to tell from here, if your condition is worse than normal. Removal of a shim or two under the WRD ( warm up device) will lean the cold warm-up of the injection system without big changes after warm-up

stickandrudderman · « **Reply #2 on:** December 04, 2020, 08:44:15 »

Black soot is a sure sign of over-fuelling and since you complain of heavy fuel consumption the two are inextricably linked.
Before going for the "advanced" adjustments are you sure it's not just in need of a proper tune-up?

PSB · « **Reply #3 on:** December 04, 2020, 19:29:13 »

Thanks both for the feedback.
Even on warm starts it gives off this soot. I drive it for about 20 minutes, then if it rests for a few minutes and I restart it will shoot off this heavy soot.
I have spent quite a bit of money on yearly tune ups ( tried MB classic center , other place that just handles classics with lots of e type jags etc , another place that does German classics mainly Porsches , etc )... But I always had this heavy smell on start up and it's always had very high fuel consumption. Just didn't link the smell to soot as I was always in the car when I started it up. None of these guys ever raised any issue .... But I'm sure there is one.

stickandrudderman · « **Reply #4 on:** December 05, 2020, 11:13:25 »

Take it to any place that can measure Co and HC from the exhaust and let us have the readings.
There's sure to be a local place that can do that.

PSB · « **Reply #5 on:** December 05, 2020, 22:35:02 »

Thanks Stick I'll do that and let you know.
We had "summer" until this weekend but now its forecast rain for a week ...so as soon as I get a weather break
Regards
Pedro

PSB · « **Reply #6 on:** December 07, 2020, 15:00:51 »

Stick,

Took the car today to a place that certifies if the car is roadworthy ( your MOT certificate I believe ). My certificate is valid until 2022 as it was classified as a vehicle of historic interest by the Portuguese classic car register of the ACP ( local equivalent of RAC ) so it was a voluntary inspection....luckily otherwise the car would have failed based on only one issue : emissions . Maximum allowed for classic cars is 4,5% CO and my car had almost 10% ... Every thing else was ok.
Here is a photo of the emission test result . With Portuguese titles but I'm sure it's understandable.
I believe this is an issue from the day I bought the car in 2016 and no one has really been able , OT focused or concerned or knowledgeable enough to sort it out even though I raise it every year when taken for service . As I also said fuel consumption is very high . Guy at the inspection center said he would suspect too much fuel being injected .
Thanks
Pedro

Peter h · « **Reply #7 on:** December 07, 2020, 15:54:47 »

Trying out will only benefit the workshop at some point. I give you the advice to overhaul the injection pump.
Peter

stickandrudderman · « **Reply #8 on:** December 07, 2020, 19:55:59 »

Both your Co and your HC are way too high. If you lower your Co to around 4% you may find the HC will lower too but at those numbers I suspect there's an underlying issue. I consider anything more than 600HC to be worthy of investigation but a good engine will have the HC down at 200.
HC is unburned fuel so with high HC you have a combustion problem which can be caused by a whole host of things. You'll need to start with basics like compression, valve clearances and ignition timing.

PSB · « **Reply #9 on:** December 07, 2020, 23:29:36 »

Thank you both for the inputs.
Need to decide on the approach ...I can't judge as I'm an absolute zero regarding anything close to a car engine....and 3 different garages have done the "tune up" of the car over the last 3 years with no success in this matter, worse actually not referring that anything was wrong ! I actually think both emissions and consumption have actually gotten worse over last couple of yeRs.
Strangely though the car does seem to drive very well....

Peter h · « **Reply #10 on:** December 08, 2020, 07:38:47 »

With lots of gasoline, you'll all do well
Peter

Cees Klumper · « **Reply #11 on:** December 08, 2020, 13:24:00 »

It looks like the CO measurement at 9.99% exceeds the diagnostic machine's max limit - meaning the real CO could be (much) higher even than 10%.
Could be a leaky cold start valve, which maybe explains why there is the black soot on warm starts as well as the high fuel consumption. It's just always adding fuel to the mixture. I believe this can be easily checked by removing the little bolt on the side of it and turning on the ignition - check the technical manual or search the site.

PSB · « **Reply #12 on:** December 08, 2020, 15:11:19 »

Thanks Cees,

I've tried searching but my zero mechanical knowledge is a big limiting factor here. Can't make anything of the things I found....Chinese to me . All I can do is collect these inputs to try to pass onto a mechanic .
But regarding your input ... If I unscrew it and start the ignition what is the expected result that would tell me something ?

Regards
Pedro

Cees Klumper · « **Reply #13 on:** December 08, 2020, 21:10:01 »

If with the ignition on fuel drips out of the small hole that the bolt goes in, then the valve is leaking fuel constantly and needs to be repaired or replaced. That is my understanding at least.
Other possible causes in addition to Stick's suggestions that I would (ask your mechanic to) look into are poorly adjusted gas linkages, faulty barometric compensator on the fuel injection pump, leaking fuel injectors, misadjusted fuel injection pump.

PSB · « **Reply #14 on:** December 09, 2020, 22:38:22 »

Being a pain ...but I really want to collect your suggestions to take to the mechanic.
Today I had a look around the engine bay and notice that
1) there seems to be fuel/oil leaking around the no 1 spark plug and
2) another connection near it ( fuel line into the head ?) .
3) fuel injectors connection 1 and 5
See photos

Clearly the car is leaving an oil type puddle on the floor .
Also
4) after driving if I open the trunk/boot it smells of petrol. When not driven recently , no smell.
Does this give any pointers to the potential problem or could it be unrelated to my emission/smell soot and too rich mixture problem . .?
Regards
Pedro

Bonnyboy · « **Reply #15 on:** December 10, 2020, 00:33:34 »

Pedro - re the smell in the boot -that could be the gasket over the sending unit in the top of the tank - put a paper towel tube over that and sniff to see if it smells bad - my guess though is the little fabric flexible hoses on the vents that exit the fuel tank to the passenger side - mine are very "aromatic". You may need to remove the fuel filler cover bracket. Also if they come out ok check that the tank isn't rusted through on top where the flexible cushions are located. You would need to drop the tank a bit and be careful they are heavier than they look and if you open the bung on the bottom there is no stopping the fuel that will come out and in a hurry - be careful with gasoline - have a fire extinguisher handy just in case.

Charles 230SL · « **Reply #16 on:** December 10, 2020, 01:53:18 »

Pedro, that oil leak in your 2nd and 3rd photo is coming from the tachometer cable: https://www.sl113.org/forums/index.php?topic=13061.msg88712#msg88712. Your tachometer drive needs a new seal. MB part number is 007-997- 7346; here's a link with a picture: https://www.authenticclassics.com/Seal-Ring-for-Mercedes-Speedometer-Drive-p/auth-008887.htm. This leak is a fairly common problem (I had to replace mine 3 years ago).

That oil leak around the number 1 plug is most likely coming from the rocker arm pivot above the spark plug. I had this same problem a few years ago: https://www.sl113.org/forums/index.php?topic=16157.msg111691#msg111691

PSB · « **Reply #17 on:** December 10, 2020, 08:39:08 »

Thank you both for the inputs.
Collecting info for the mechanic.
So that in the 3rd photo is the tachometer cable ! Embarrassing .....I thought it was the fuel line.... Little knowledge is a dangerous thing ..

Regards
Pedro

PSB · « **Reply #18 on:** December 10, 2020, 22:24:06 »

Hi Cees,

Is this the cold start valve you were referring to in my issue with the excessive co2 emissions and too rich mixture ?
Also when you refer to removing the screw and then turning on the ignition ...it is just turning the key not actually starting the engine , right ?

Regards
Pedro

mrfatboy · « **Reply #19 on:** December 10, 2020, 23:20:38 »

Pedro.

Take a look here.

https://www.sl113.org/wiki/Engine/ColdStartValve

I would also advise taking some time and skim over the Tech Manual. You don’t have to understand everything but just skim through for the basics and orient yourself with the engine and components. 👍

PSB · « **Reply #20 on:** December 11, 2020, 12:03:59 »

Very helpful thanks .
At least that check I can easily do now .
I've joined full membership now and will take up your suggestion of "going through " the tech manual to become a little bit less ignorant .... At my mechanical knowledge level improving a bit is very easy !

Thanks
Pedro

PSB · « **Reply #21 on:** December 11, 2020, 18:20:51 »

One item checked and off the potential problem list .... The CSV after the screw is removed and ignition on does not leak at all.
This was the easy check for me once I found out where the CSV was ....
I think all other checks will need to be done by a mechanic unfortunately.
I started the car today with some cardboard against the exhaust pipes and wow just 2 seconds and it was totally black .....lots of black soot on the bumper and floor as well, deflected by the cardboard . I noticed the soot is actually pretty wet , almost gunge like.

PSB · « **Reply #22 on:** December 11, 2020, 18:25:27 »

The photos ... Frightening!

Mike Hughes · « **Reply #23 on:** December 11, 2020, 19:57:40 »

Think back to high school chemistry class:

Combustion is the chemical reaction of combining a hydro carbon with oxygen, which results in carbon dioxide and water. Combining excessive amounts of a hydrocarbon in the reaction will result in carbon dioxide, water, and carbon. So the black soot is nothing more than a sign of a too-rich mixture, while the water in the black grunge is nothing more than a normal byproduct of combustion.

Plain steel exhaust systems need to be periodically replaced because the water in the exhaust pipes and mufflers makes them rust out. Stainless steel systems help to take care of that problem. However, Milady's sooty stockings and and pants legs will be a source of lively conversation until the rich mixture problem is addressed.

col320ce · « **Reply #24 on:** December 12, 2020, 22:58:44 »

I'd check that the warm running device is turning off... It will stop sicking in air if it's shutting off correctly when warm.

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Author Topic: Exhaust emitting black particles at start up (Read 6919 times)