General Diesel smoke test results for MOT - What do the figures mean?

Discussion in 'Lounge & Gossip' started by dbrooks65, Monday 30th Nov, 2015.

  1. dbrooks65 Valued Contributor ★ ★ ★ ☆ ☆

    Scotland Dave glasgow

    My car passed its MOT today but just wondered what all the figures on the smoke test mean.

    K(1/m) Min Max
    1 2.05 24 33
    2 1.06 26 36
    3 1.16 28 40
    4 0.76 32 44

    Oil temp: 80 deg C
    Average reading: 0.99 1/m

    Are these figures good, bad or are they irrelevant?
  2. jimjams Guest

    The probe measures the density of the smoke, from its "opacity"

    K 1/m is the "opacity" (2.05 in the first row) , "2.05" is related to the number of smoke particles. The other two numbers in the row are the smoke temperatures

    I think that the opacity for it to pass depends on several factors, typicically less than 2.5, and several tests can be made for it to pass
    Last edited by a moderator: Monday 30th Nov, 2015
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