E270 CDi Smokey exhaust

james2747

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E270 CDI 2003
I have only had the car a few weeks (2003 year, 81,000 miles) so still getting used to it.
However, I notice the exhaust is quite smokey even under moderate acceleration.
Its not a case of plumes of smoke out the back ... but certainly it smokes more than it should.
The first thing I would normally check would be the crankcase ventilation system ... but unlike my previous car, it doesn't appear to have any serviceable items such as a breather filter.
I don't think it's a case of worn rings creating excessive 'blow by' so is there anything else I can look at that may be causing this excessive smoking.
I would add that before I got the car it had a decent service history and the engine appears to be in good condition and pulls well ... although it does sound very much like a tractor when idling ... but quiet when driving along.
MPG ... if I can believe the computer is 47 m.p.g. on a long motorway run yesterday ... even with my smokey exhaust.
Oil and filter changed a couple of weeks ago.
Any suggestions most welcome.
 

sonic

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I had a 2006 CLK270CDI, under heavy acceleration you could hide HMS Hood. Its an old engine design, which dose blow out a lot of smoke. Is it burning oil?
 
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james2747

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What colour smoke?
Hi LostKiwi
Its a darkish / oil type smoke ... definitely not white.
Its worse when doing about 50 / 60 ... put your foot down and its very noticeable till you ease off the accelerator.
Not so obvious when moving off from a stop.
Very difficult to describe it without you seeing it ... doesn't billow out ... but if I was following a car that was doing it I'm sure my comment would be, " Phew, he has got a problem".
 

LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Black/grey smoke is incomplete combustion and can be caused by airleaks, bad injectors or over rich mixture. In general whilst not desirable its not overly harmful. A decent diesel specialist should be able to sort it out.
Blue smoke is oil and is bad news.
White is unburnt fuel and will usually smell of diesel and can be caused by timing, injectors or low compression.

Some engine chuck out black smoke if they've been driven gently for too long.
 

V6Matty

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My old 270 of the same ages was the same, egr was sticky so had that removed during a remap, also evaded up replacing the air box as they were prone to cracking at the rear. I'd say your best option here would be running some cleaners through a few tanks, a few Italian tune ups and ensure your getting up to 90 quickly
 

amustali

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Check your Mass Air Flow sensor, could be giving incorrect air levels causing extra fuel to be injected.


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RUBBER_UNDIES

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2003 w211 E270 177 BHP
Also check the fuel temperature sensor. It is located directly on the high pressure pump at the front left of the engine.
 

alexanderfoti

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Check your Mass Air Flow sensor, could be giving incorrect air levels causing extra fuel to be injected.


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On 270cdi's the MAF is not used for fueling, only for input to the autbox, and to check the EGR is working.
 

Viktor E270

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W211/2002/E270 CDI
I have only had the car a few weeks (2003 year, 81,000 miles) so still getting used to it.
However, I notice the exhaust is quite smokey even under moderate acceleration.
Its not a case of plumes of smoke out the back ... but certainly it smokes more than it should.
The first thing I would normally check would be the crankcase ventilation system ... but unlike my previous car, it doesn't appear to have any serviceable items such as a breather filter.
I don't think it's a case of worn rings creating excessive 'blow by' so is there anything else I can look at that may be causing this excessive smoking.
I would add that before I got the car it had a decent service history and the engine appears to be in good condition and pulls well ... although it does sound very much like a tractor when idling ... but quiet when driving along.
MPG ... if I can believe the computer is 47 m.p.g. on a long motorway run yesterday ... even with my smokey exhaust.
Oil and filter changed a couple of weeks ago.
Any suggestions most welcome.
Hi James, sorry to bother you, did you fix that smoking please ? I have the same problem, last year i was facing limp mode (also without check engine light on) EGR (replaced last year), new intake manifold (last year), 3 repassed injectors (give correct values as per diagnostics), recently replaced turbo along with regular service (oil, filters)but that smoke is like you say, it is visible especially during night when car is behind me and in a mirror I can see heavy blow and it looks very hazed.

Thanks
 
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james2747

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Hi Viktor
Problem not fixed by any specific action but it is definitely better than it was.
Like you, it is still noticeable at night when I put my foot down and exhaust fumes are visible in the head lights of car behind but smoke not as bad as a year or so ago.
Not sure why it has improved as nothing done to the intake/exhaust system to improve matters.
I still have problem of car going in to 'limp home' mode if/when I slam accelerator down ... so perhaps I'm sub consciously not being as heavy footed on using accelerator as I once was.
I've pasted in (below) a response I got from 'Lost Kiwi' when I posted my original thread in 2018. Hope its of use.
Black/grey smoke is incomplete combustion and can be caused by airleaks, bad injectors or over rich mixture. In general whilst not desirable its not overly harmful. A decent diesel specialist should be able to sort it out.
Blue smoke is oil and is bad news.
White is unburnt fuel and will usually smell of diesel and can be caused by timing, injectors or low compression.
Some engine chuck out black smoke if they've been driven gently for too long.


Sorry can't be of more help
Regards
James
 

Viktor E270

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Hi James,

Many thanks I was just interested how you solved it. Touch wood no limp mode so far but like i said EGR and Intake were replaced it helped. All the best :)
 

joderest

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ML270 2003
Hi.
If this the same 2.7 as in my W163, then here is a couple of suggestions.
1) check the turbo activator is working correctly and not being lazy, check for any air leaks in the pipe that operates it, the activator being lazy can mean more smoke.
2) the issue my engine had was oil being pushed towards the turbo from the breather, changing the "filter" thing on top of the engine helped, but what helped more was fitting an oil catch can in the breather pipe.
I only get black smoke now when i really floor it and it soon stops.
 

philreed52

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270clk
Hi Viktor
Problem not fixed by any specific action but it is definitely better than it was.
Like you, it is still noticeable at night when I put my foot down and exhaust fumes are visible in the head lights of car behind but smoke not as bad as a year or so ago.
Not sure why it has improved as nothing done to the intake/exhaust system to improve matters.
I still have problem of car going in to 'limp home' mode if/when I slam accelerator down ... so perhaps I'm sub consciously not being as heavy footed on using accelerator as I once was.
I've pasted in (below) a response I got from 'Lost Kiwi' when I posted my original thread in 2018. Hope its of use.
Black/grey smoke is incomplete combustion and can be caused by airleaks, bad injectors or over rich mixture. In general whilst not desirable its not overly harmful. A decent diesel specialist should be able to sort it out.
Blue smoke is oil and is bad news.
White is unburnt fuel and will usually smell of diesel and can be caused by timing, injectors or low compression.
Some engine chuck out black smoke if they've been driven gently for too long.


Sorry can't be of more help
Regards
James
Hi had similar problem with my 270clk . Mine went into full cardiac arrest and stalled under kickdown( restarted as if nothing happened) , scared s**t out of me when overtaking !!! No fault codes or EML .Took to merc specialist that blamed supermarket fuel.Replaced fuel filter and put in turbo cleaner and injector cleaner .Runs fine now but as recommended premium fuel only and injector cleaner every 4-5 fillups . Still get EML on once in a while but no loss of turbo and no limp mode and runs like a watch .

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