Are Diesels slower in Winter?

Discussion in 'Engine' started by Simon_M, Oct 29, 2008.

  1. Simon_M

    Simon_M Hardcore MB Enthusiast

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    Wife is complaining the car is 'sluggish' in the recent mornings. I told her that it was just because it is very cold at the mo and diesel thickens in the colder weather.

    It seems to be from starting after the car is sat overnight. I have not experienced it myself but she says it did not do it last year and maybe the Brabus chip is fooked.

    My Passat is like a dog (also diesel) first thing so I am not really fussed.

    Am I bullshyating her or is the car playing up? any advice?

    Simon
     
  2. SilverSaloon

    SilverSaloon MB Club Veteran

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    Dont push a cold car anyway. However it does thicken up. I notice this more when I run on veg oil - very slow if its not mixed much with petrol/diesel.

    I suspect straight diesel aslo thickens and has the same affect, but just not as bad.

    I more or less ignore hard gearshifts/sluggish type issues if the car is not at its standard temp. Only worry if it does strange things once nice and warm.
     
  3. BTB 500

    BTB 500 MB Club Veteran

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    Good quality branded diesel has a different formulation in winter, and I don't think you should notice any difference in performance at the sort of temperatures we get here.
     
  4. tromppost

    tromppost Hardcore MB Enthusiast

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    it's more than lightly a traffic cone stuck under the car, it will work it's way free soon!

    Sorry could not resist.
     
  5. bigyin1

    bigyin1 Hardcore MB Enthusiast

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    I have certainly noticed this in the last few days when temperature has been near 0, really sluggish on full throttle below 3,000, more than usual anyway ;) Once warmed up OK though.
     
  6. Bobby Dazzler

    Bobby Dazzler MB Club Veteran

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    I've found that all cars are not on top form in very cold weather having been stood over night - both petrol and diesel.

    Diesel does seem to be affected more though - louder, more clatter, etc until up to normal operating temperature.

    Dread to think what it's like in places where it's REALLY cold.


    Come on dieselman. Your forum needs YOU!
     
  7. Will

    Will MB Club Veteran

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    I'm probably in the minority here, but cold weather seems to make my cars perform better - petrol and diesel. Certainly once 'warmed up' anyway.

    I'd always assumed that the colder air was more dense = more oxygen when filling the cylinders?

    Will
     
  8. OP
    OP
    Simon_M

    Simon_M Hardcore MB Enthusiast

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    LOL at the cone!

    Yeah, she always pushes it too hard when cold and rarely waits for the ignition light to go out before starting it, despite abuse from me every time she does it.

    I'll take it for a run at he weekend and probably diagnose a shoe or bag under the pedals!

    S
     
    Last edited: Oct 29, 2008
  9. Shude

    Shude MB Club Veteran

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    My c230k goes like a rocket on cold mornings! Much more responsive and needs a lighter touch in order to make safe progress!
     
  10. Will

    Will MB Club Veteran

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    I agree, mine definately used to as well :)

    Will
     
  11. bigyin1

    bigyin1 Hardcore MB Enthusiast

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    100% correct, especially on forced induction cars, they will have more power in winter than in summer and the manufacturers adjust the ECU to suit...
     
  12. Bobby Dazzler

    Bobby Dazzler MB Club Veteran

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    I agree - theoretically that should be the case - warmer ambient temperatures degrade performance.

    Maybe I read it wrong but I think the OP was coming from the perspective of a cold start, ie not yet up to operating temperature.

    If memory serves, air is at it's most dense at 4 deg C, but as it enters the engine bay and then through to the combustion chamber it warms up quite a bit, and that increase in temperature more than offsets the maximum density in perfect ambient temperatures.

    So on that basis you want ambient temperature to be much cooler still than 4 deg C - especially for forced induction cars, as it gives the intercooler a head start!!
     
  13. lynall

    lynall Hardcore MB Enthusiast

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    Every diesel i have ever owned has been a tad sluggish from a cold start, reluctant might be a better word and i cant blame them either!



    Lynall
     
  14. BTB 500

    BTB 500 MB Club Veteran

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    Hmm .. not noticeable on either of ours.
     
  15. Uberwagon

    Uberwagon Hardcore MB Enthusiast

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    When the cylinders, pistons etc are warm then we very very rarely see weather cold enough for it to affect the fuel itself.

    It's simply the car taking longer to warm up.

    Dave!
     
  16. recycled

    recycled Hardcore MB Enthusiast

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    i thought they were slower all the time.



    ehhrrmm where is my hat? !!!!
     
  17. lynall

    lynall Hardcore MB Enthusiast

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    So true:D well all mine were Landrovers:rolleyes:



    Lynall
     
  18. grober

    grober MB Club Veteran

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    What grade of oil are you using? Changing to an oil having lower/wider viscosity at low temperatures might help- It will definitely help the starting! Or you could fit a coolant preheater?
     
  19. Dryce

    Dryce MB Club Veteran

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    I think you're confusing this with water which is at its most dense at 4 deg C

    Air gets denser as the temperature drops.
     
  20. CiaranMcKeown

    CiaranMcKeown Hardcore MB Enthusiast

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    Correct, it needs to be nice and cold/dense i.e. more oxygen molecules to create a bigger bang in the cylinder.
     

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