Tailpipe droppings

[minyak]

Hi guys,

Need help!!!

Have any of you seen tailpipe droppings I've been getting on my driveway. It occurs overnight. Its watery and black-green-bluish in colour but becomes powdery when dries. I'm using my exported C220 CDi ( W203 UK Spec) in the far east where its fairly humid, but never had this happen whilst using the car in the UK. The car has got 100k miles on the clock. Is this a symptom of the interior walls of the tailpipe deteriorating or something else due to the weather here. The local diesel used here has got a higher sulphur content but the cetane rating average is higher than in UK. The engine performs smoothly without any loss of performance though. Are the interior walls of the pipe deemed for inspection in this case. Also, there's a bit more smoke (whitish/grey) at idle but its sporadic in nature and comes out once the engine has warmed up. Could the smoke be related to this tailpipe drippings???? Cheers.

 

[grober]

whats the colour of your antifeeze in your coolant?

 

[Dieselman]

Ditto.

 

[minyak]

Hiya,

Ok I had a check of the coolant, opened the cap and dunk a white soft tissue into it the colour of the coolant looks a light greenish in colour. It does look similar to the droppings, of course the droppings has got carbon soot in it too. Are we getting on to something here, how is it that the coolant fluid got into the exhaust system (if this seems to be the case)....thanks for your help in this guys...

 

[lotusmark2]

Hate to say it but is this not pointing toward head gasket or cracked block (more lightly the first)

 

[minyak]

Hiya,

Yes possibly (hope not), but overheating due to loss of coolants would occur aint it?!! Particularly in warmer weather around here. I recently drove up very steep hills and was observing the temperature gauge most of the time. there was no signs of overheating and all seems well. Another mate here who is using a similar model here did report of similar droppings from his tailpipes when he first took delievery of his car. But it disappeared after around 5 tankfuls of fuel and now all seems fine. I'm on to my 4th tank of fuel now, could it possibly be some sort of washing/fluishing out of combustion by products from the exhaust system. Also, the smoke come out sometimes and not all the times...kinda perplex..??

 

[grober]

high humidity or head gasket

There is the possibility that if the climate is very humid that the water content of your exhaust is higher than in the UK. This might lead to some sort of "wash out" of exhaust material. My money would be on some stray metalic material from the catalyst. As far as head gasket is concerned best to keep a close watch on things, monitor for oil staining in the water or water emulsion in the oil. this can just be a trace line of white emulsion in the darker oil at first. Overheating and drop in oil pressure (difficult without a gauge) are also symptoms at a later stage. If you dont want to wait and see then a proper compression test on all cylinders should reveal something. Maybe your local MB dealer could help also if you ask them about the problem.

 

[minyak]

Hi again,

I also checked the coolant levels which indicate the level is fine (+ the steep hilly drives which indicate no overheating or loss of coolant). Actually I've had serviced the car a couple weeks back but the MB dealer said that nothin was wrong. Another thing I forgot to mention also was that the car was previously remapped using a tuning box and there's also a possibility that the smoke is due to the very humid air (+35 degrees C) here which makes combustion of the 'additional' fuel due to tuning more incomplete (in efficient). I dont think (and hope) its got to do with the head gasket. But I shall be monitoring the coolant for any sign of contamination though.

Any more thoughts or things to look out for would be most welcomed...Cheers...

 

[lotusmark2]

The only other thing I would suggest is see if you can get an additive to put in the fuel tank that absorbs moisture, I think Wynns do one if not I know there are plenty about, just incase you have some unwanted condensed moisture in the fuel system. May not help but worth a try considering it will be quite cheap to buy.

 

[Satch]

Suspect what you are getting is a result of high sulphur fuel, a complex hydocarbon/sulphate mix. If your (uk) spec car has a catalytic converter, they do not like high sulphur fuels and it may have given up by now.

Answer is in here somwhere

http://www.nett.ca/faq_diesel.html

 

[minyak]

Me again,

This is interesting and may point to a solution; wrt to the fuel additive which absorbs moisture. The other mate of mine did the same with his car and it seemed to help get around the condensation problem (which could be the issue here). They have these additives here, so will be hunting down for it possibly tomorrow. What I dont understand is that how could moisture/water get through into the combustion process. I know that there is a water filter element/separator which is part of the fuel filter?? Isn't this element doing its job, or is just that in such humid weather, moisture would somehow find its way through the combustion process and out into the exhaust...??!!

 

[minyak]

Hi Satch,

Dont think that the sulphur level is an issue here. In fact many new CDi models are being sold and used where I live now. Yes, we have certain brands of fuel which has terribly high sulphur contents (2000ppm) but some are at Euro 2 levels which limit it to less than 500ppm. Uk levels are hovering <50ppm now I think. But we've been advised to not use to ultra high sulphur fuels. Also to get around and minimise the effects of sulphur 'poisoning' the cat converter, one should at least once a week make sure to rev the engine beyond 3000rpm whilst heat soaking the exhaust to blow out particulates/matters within the system. Also the servicing intervals are set lower as compared to UK intervals to account for the higher sulphur levels here. Besides mercedes, we also have the BMW 530D running around here as well and I am informed that these cars are identical to the UK specced ones.

 

[Dieselman]

With the additional info we now have it looks as if the problem is the high sulpher fuel is reacting in the cat. 500ppm is high for a cat equipped diesel. Are the CDIs that are being sold have a cat fitted, probably not as it isn't a requirement for Euro2 emissions, due to the sulpher.
The increased sulpher will also create more black smoke as it's the sulpher that we see as soot.

 

[minyak]

Hi dieselman,

Yes as far as I know the diesels here are sold with the cat fitted (I'm talking about the latest Euro 4 diesel models). My engine is a Euro 3 unit. There have been stories of cars with the cat been clogged and replaced earlier than intended. Some of them actually remove the cat altogether, which increases performance but this may cause problems with the turbocharger later on. But both merc and bmw still sell thier cars here without much of an issue with the high sulphur content. Only thing they recommend that the servicing intervals are shortened to 15000 km (10k miles) instead of following the on board computer data. Another thing is to follow thier recommendations with the fuel brands that have relatively low sulphur content, there are with around 200-350ppm. I've seen cars here emit black smoke, but not terribly so and only during full throttle and from stand still. Anyhow, with this conditions what would the estimated lifespan of a cat, anyone know?? Cheers.

 

[minyak]

And another thing, how would I know if the cat has busted??

 

[grober]

The Sulphur theory.

Normally too much sulphur in fuel will poison the catalyst by reacting with the precious metals on the honeycomb thus reducing their ability to "convert" the CO VOC's and NO's. this can theoretically be reversed by subsequent burning of low sulphur fuel. However in the absence of low sulphur fuel the sulphur levels will build up eventually burning to form SOx gases. Combine this with NOx gases no longer reduced to N2 and O2 by the poisoned catalyst and the WATER produced as a natural combustion product and you have the equivalent of "hot acid rain" in your catalyst/exhaust. This will start to react with the internal support structure which will possibly contain aluminium and other metals . Maybe this is the blue/green black material?? Again chemical analysis of the material would tell you for sure if you are very concerned. SEE http://en.wikipedia.org/wiki/Catalytic_converters if you want to check if your cat is broken a good exhaust gas analyser in experienced hands should tell you the answer.

 

[Satch]

Technology moves on and many of the more recent Diesel Cats. are more tolerant of Sulphur than a few years ago but Ultra Low Sulphur Diesel has since 1999 been the standard to which many European car makers have designed for. Clear that the more Sulphur the shorter the Cat. life will tend to be. Maybe car makers have been a little more silent about that than they should.

There is an EU Directive to make "Sulphur Free" diesel (10ppm or less) the standard across the EU by 2010. This is a must have technology for without that the next stage in reducing Nitrogen Oxide emissions from diesel engines and making regenerative particulate filters more efficient cannot be reached.

 

[Dieselman]

And another thing, how would I know if the cat has busted??

If it's blocked the engine will be straining, if it's poisened the exhaust fumes will smell of diesel.