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W210 e220CDI - severe knock and grey smoke only between 2-4000 RPM

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by onepoundmercedes, Jul 10, 2017.

  1. onepoundmercedes

    onepoundmercedes New Member

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    Your Mercedes:
    W210 E220 CDI 2002
    Hey all,

    Hope someone can shed some light here for me.

    I have a W210 E220 CDI with 97,000 miles on the clock. Recently it has started to knock badly and smoke (grey and LOTS of it) when accelerating but only above 2-2500 rpm AND only when it has been up to temperature for a while.

    It is getting worse with time as well, and the other day it suddenly lost power and knocked really badly with smoke, just under cruise conditions (around 65mph) then after a second it was back to normal.

    I have put it on a CMT diagnostic machine (I am retired mechanic and have diags available) but there are no fault codes and the live data all looks sensible.

    I changed the MAF sensor just in case but no improvement. MPG is unaffected and it starts and runs perfectly.

    I have tried flooring it in neutral while looking at the data and, once warmed up, it always knocks badly and smokes as it rises through 2-4500 RPM but then as the limiter kicks in at 4500 it runs fine with no smoke or knock...

    The boost pressure is ok going up to about 1.6bar and the rail pressure rises to around 1200bar then drops back to about 600 as it evens out at 4500 RPM.

    injector trim is all 0's and injected qty is evenly distributed across injectors. It starts first touch every time hot or cold.

    It had new oil & filters (oil, air & fuel) about 6 months ago and has only done a few hundred miles in that time.

    I'm all out of ideas now so any thoughts welcome.

    Many Thanks in advance.

    Bob..
     
  2. John Laidlaw

    John Laidlaw Senior Member

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    Your Mercedes:
    UnMercs BMW i8 Volvo XC90
    How's the fuel quality?
     
  3. bembo449

    bembo449 Senior Member

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    Your Mercedes:
    Mercedes Cl500, land rover discovery 3 , insignia vxr , shitron dispatch
    when you say knock , are you meaning diesel knock or a mechanical knock like big ends going ?
     
  4. OP
    onepoundmercedes

    onepoundmercedes New Member

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    Think it's ok. There's no water in it, or at least none in the bottom of the filter. I always use BP standard stuff from the garage next door. It's on it's third fill since the trouble strarted so think it should be ok.
     
  5. OP
    onepoundmercedes

    onepoundmercedes New Member

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    Diesel knock, a bit like extreme pinking..
     
  6. bembo449

    bembo449 Senior Member

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    Your Mercedes:
    Mercedes Cl500, land rover discovery 3 , insignia vxr , shitron dispatch
    so could be a fuel issue then ? out of interest is the water level ok ?
     
  7. OP
    onepoundmercedes

    onepoundmercedes New Member

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    Your Mercedes:
    W210 E220 CDI 2002
    Yea, water's fine, check it regularly but the level never changes. I put a new thermostat on it last winter because it was taking for ever to get up to temp and I'm happy the cooling system is all ok and that there are no leaks or dodgy head gasket...
     
  8. LostKiwi

    LostKiwi Senior Member

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    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    I've had this on our boat - it was air getting into the fuel due to a loose fuel line but it also wouldn't start properly.
    Have you checked your intercooler hoses and intercooler for leaks?
     
  9. Westheath

    Westheath Senior Member

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    Your Mercedes:
    Empty garage, awaiting new toy :)
    Pull the injectors and send them off for servicing.

    Deisel BoB is ok :)
     

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