CLK270cdi - how much smoke is too much?

Wirral_guy

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Hi all

I have recently bought a '54 plate W209 CLK270cdi with 68k on the clock. When I test drove it, a pipe had come off and it was blowing loads of smoke and making a rushing air sound (like the climate fan was speeding up and slowing down) when on the move. This was fixed and I bought the car. I am generally pleased with it as it is beautiful to look at and drive but 2 things are bothering me slightly:

1. How much black smoke should there be under acceleration? Although I couldn't describe it as clouds there is a definite plume of smoke when I put my foot down (even does this when stationary).

2. I have supposedly upgraded from a Volvo S60 D5 diesel yet the CLK seems a lot 'lumpier' than the Volvo diesel. It feels like a step back in technology and sounds so much more diesel'y than the D5.

Should this be so or could the 2 items be related and I have a problem? Could the original problem of a blown pipe have left a residue that is now blowing out under acceleration?



Thanks in advance for your advice and comments.

Dave
 

Alex Crow

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is the `lumpiness` pronounced at idle? injector/s problem/s are most likely.

smoke wise you should not see any at any engine speeds. the possible causes are many and varied, but give it chance to purge any built up residues in the exhaust sytem by driving with bursts of full throttle and rpm with hot engine then re-asses.
 

jibcl500

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Does the CLK smell oily or give any diesel fumes inside the car? if so it could be injector seals, best find yourself an indie mercedes garage near you and have them take a look.
Running Star diags on the car would also be a good idea.

jib
 
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Wirral_guy

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Th lumpiness seems more pronounced from cold but is still not smooth at working temperature. The smoke is bluish/black and can be seen when any pressure is applied to the throttle.

There are no smells inside the car at any time that I am aware of.

Can anyone recommend an indy close to Wirral/Chester that I could drop into for a check?

Thanks

Dave
 

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I think it is an injector problem,,it only takes 1 to do what your car is doing
 

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I have a 220cdi with 12K on the clock. I emailed my MB dealer ' I have noticed some smoke on acceleration and I did not expect this on a Mercedes! Can you confirm if this has a Diesel Particulate Filter (and which type - open or closed) or not and whether this needs a strong burst of acceleration very now and again to clear the filter depending on whether it is an open or closed type?' His answer was 'All diesels give out smoke on acceleration, no DPF fitted to this vehicle it is a cost option for the UK market.'

So it would appear that some smoke is normal and to be expected? Forum experts -Is this correct?
 

jibcl500

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Ive never seen a 220cdi or 270cdi smoke unless there was something wrong. I have a customers 270cdi which has had a long term smoke problem to the level where hard throttle fills the street with black smoke, air filter was clogged, injector seals all needed to be replaced which helped for a week but then the smoke came back. EGR is next on the list.

jib
 

survey

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jibcl500 - to be fair mine emits only a small puff on acceleration out of roundabouts etc. However, I am somewhat disappointed that even this should occur!
 
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Wirral_guy

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That's why I am a little concerned. I know all diesels emit a kind of haze under acceleration (best seen at night with following headlights) but this is a little more than that and fairly black in colour. It is approx (very!) 15-20% of the exhaust gas but noticeable all the same.

Dave
 

Baldrick123

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Ive never seen a 220cdi or 270cdi smoke unless there was something wrong. I have a customers 270cdi which has had a long term smoke problem to the level where hard throttle fills the street with black smoke, air filter was clogged, injector seals all needed to be replaced which helped for a week but then the smoke came back. EGR is next on the list.

jib

I have a smokey w203 220cdi which has a new filter and four new injectors. Is the EGR costly to replace? as this might be my next course of action.

Thanks

Andy
 

survey

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Wirral guy - Yours does seem to worse than should be expected.

jibcl500 now make me worried thta mine should not be showing ANY smoke??
 
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Wirral_guy

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Wirral guy - Yours does seem to worse than should be expected.

That's only under acceleration, cruising has no smoke that I can tell, but that is what I thought - just a little too much for my liking. I think a trip to an indy is called for just to check.

Dave
 

survey

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May be our Indie specialists can post a comment here. Should we expect no smoke whatsoever even under heavy acceleration?
 
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Wirral_guy

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Well, I got to the indy garage (Wirral-Merc - highly recommended if you're on the Wirral, very friendly people and didn't charge for the STAR check).

The guy hooked it up to STAR and it is showing no faults except for the MAF sensor. This is reading 459-460 at idle and I think it should be around 250.

Is it easy to give it a clean? I have seen the MAF clean DIY but not sure if it'll be the same for the 270cdi engine. If not, or it's knackered, are these expensive to replace?

Thanks

Dave
 

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hi scouser (ey? ey? ey? :) ) you mention lumpiness, is this at idle/tickover/750rpm? if so injector problem as malc says, das smooth running analysis will tell which one (MB computer analysis).

your cars should not have noticable smoke guys! yes egr valves are possible causes, mainly on 320 cdi2 engines, but most common by far is leaking intake tract losing pressure after maf. ecu injects fuel according to maf values (as well as other inputs) but the pressure, and so volume, is lower than metered so you get overfuelling black smoke. injector sealing problems will not cause black smoke, nor will DPFs.
 

Alex Crow

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oops! just read page two! you car is most likely smoking because of the scenario detailed above.

your maf however is probably ok. the garage did a test at idle and the values you quote are probably with the egr valve closed. they should have blipped the throttle and the egr valve would have opened and the mg/hub maf reading would have dropped! the egr valve stays open for approx 40s at idle then closes, every time you blip the throttle it opens again for approx 40s. the star test does advise this to the tester. alernately you have an egr fault but i doubt this test proves your maf at fault.
 
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Wirral_guy

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hi scouser (ey? ey? ey? :)

Scouser!! Scouser! I'm from The Wirral don't you know. We're all dead posh, like :D:D

The mechanic seemed to think all the injectors were running OK (a bit difficult to take all the info in from the PC screen but they seemed to be delivering various amounts between 0.3-1.0 mm/hg$%&^* or something like that)! The mechanic seemed to think anything under 5 whojiflips was fine. Can anyone confirm that?

Also, I had a quick look at taking the MAF off but it's mated to the air filter housing which has some kind of star (reverse torx!?!) type bolts and I don't have a socket like that. And I can't get to one of the screws of the actual MAF as it is too close to the top of the engine.

Dave
 

Alex Crow

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Scouser!! Scouser! I'm from The Wirral don't you know. We're all dead posh, like :D:D

The mechanic seemed to think all the injectors were running OK (a bit difficult to take all the info in from the PC screen but they seemed to be delivering various amounts between 0.3-1.0 mm/hg$%&^* or something like that)! The mechanic seemed to think anything under 5 whojiflips was fine. Can anyone confirm that?

Also, I had a quick look at taking the MAF off but it's mated to the air filter housing which has some kind of star (reverse torx!?!) type bolts and I don't have a socket like that. And I can't get to one of the screws of the actual MAF as it is too close to the top of the engine.

Dave

the guy is right about anything under 5 mm3/hub (cubic milimeters per squirt trim value added/subtracted from basic value), this rules out individual injector causing lumpy idle, but has nothing to do with smoke or lumpiness at revs. the injector test he did only looks at idling correction values and does not prove injectors are working correctly at higher rpm or under load, however if they are ok at idle will usually be ok at load.

the airfilter torx bolts will come out very happily with a normal 8mm hex socket, no probs. cleaning your maf will not reduce smoking as it will only make the maf read greater air flow (if it were soiled) and the smoke would be worse!
 

muller1

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Diesel smoke

I would be concerned if having floored my ML 270 there was not a puff of dark smoke for a second or two whilst keeping the pedal nailed.
I think ALL diesels should give out a puff of smoke on hard acceleration (you only have to follow a heavy truck for a little to see this) but once the load is off a bit there should be no visible smoke whatsoever.
If a small ammount of smoke is causing a problem to the driver and not to the guy behind only put your foot down a little so there is less (slower) acceleration this will stop the smoke, but only if ther is no problem with the engine or fuel system.

Regards

Mike
 
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Wirral_guy

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oops! just read page two! you car is most likely smoking because of the scenario detailed above.

your maf however is probably ok. the garage did a test at idle and the values you quote are probably with the egr valve closed. they should have blipped the throttle and the egr valve would have opened and the mg/hub maf reading would have dropped! the egr valve stays open for approx 40s at idle then closes, every time you blip the throttle it opens again for approx 40s. the star test does advise this to the tester. alernately you have an egr fault but i doubt this test proves your maf at fault.

Sorry Alexander, which scenario? If weather permits, I'll have a look at the MAF tomorrow just to rule it out (I might go for a drive with it off as well to see if that makes any difference). Is there anything I can do to check the EGR?

Dave
 


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