M274 'noise'

Discussion in 'Engine' started by Chris-S, Feb 7, 2017.

  1. Chris-S

    Chris-S Hardcore MB Enthusiast

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    I suspect I already know the answer, but here we go...

    The one feature of our new C350e that I really dislike is the bloody awful noise the engine makes when running. Worse when cold but not exactly sweet sounding when warm.

    It also had a really nasty clatter during warmup at certain revs but the firmware update for the turbo wastegate control seems to have improved that at least.

    So, is this 'normal' and as good as it gets? It's bearable inside the car with the windows shut but it certainly doesn't sound the way you'd expect a premium vehicle to sound. I've got a 20 year old Mondeo engine in the Westfield that has zero sound deadening in it and that sounds way nicer, hot or cold. The V6 engine in the old Alfa 166 sounds frankly awesome compared to it. Even the 5.7 in the Jeep sounds better and that's got a bad case of 'Hemi tick'.

    If it was a diesel I'd be reasonably impressed. For a petrol engine, it sounds crap.

    I don't think it would have put us off the car, but we didn't hear one until we collected ours from the dealer by which point it was a bit late really.

    So, to those folk out there with an M270 or M274, how would you rate the noise?

    TFL
     
  2. grober

    grober MB Club Veteran

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  3. OP
    OP
    Chris-S

    Chris-S Hardcore MB Enthusiast

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    I've seen that article as well as the more in depth one. No denying it's a clever thing....but i can't find the bit where it says 'it'll sound crap'. ;)
     
  4. ManiacGT

    ManiacGT Hardcore MB Enthusiast

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    I find it clatterly when cold. Bearable when warm. Harsh at high revs and warbly at low revs. It's not even like it's efficient which would make up for it.

    It's only positive as I see it is the low end torque.
     
  5. grober

    grober MB Club Veteran

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    I'll speculate that its either the "camtronic " 2 stage variable cam lift

    or the lanchester balance module with the roller/ball bearings- maybe it needs changed?
     
  6. 190

    190 Hardcore MB Enthusiast

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    Interesting video. I'm trying to figure out how it moves from one cam lob to the other. I can only see it moving across at the cam base circle but would the base circles line up for all cylinders at the same time ?
     
  7. grober

    grober MB Club Veteran

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    A slightly more comprehensive explanation- system only applies to the inlet camshaft only and there are two actuators one covers cylinders 1 and 2 and the other 3 and 4 because the paired cylinders are one up one down and the camshaft rotating at half the crankshaft speed I can only assume that there's a degree of base circle overlap where horizonal movement can be safely achieved for both ? :confused::confused::confused:

     
  8. grober

    grober MB Club Veteran

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  9. 190

    190 Hardcore MB Enthusiast

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    That sounds plausable.
     
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