E270 CDi Smokey exhaust

james2747

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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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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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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.
 
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