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Oil Breathers and effects to the engine

Discussion in 'Norton P11 Motorcycles' started by PopsRacer, Dec 1, 2019.

  1. PopsRacer


    Aug 12, 2018
    Hi all,

    Finally got my P11 registered and on the road!

    Recently realized I cooked my rebreather tube and sealed it shut. I checked the oil tank and saw it became really low. The oil has gone somewhere.

    From what I’ve read, the oil may have found a way out from the main seals. Haven’t torn everything apart yet, still reading everything twice before I do so (and have a few dedicated days off)

    I’m not quite understanding explanations on other threads that the positive pressure forces oil to find a way out of the case while running. My primary seems to be low (oil level screw = no overflow).

    Essentially, I’m mainly curious if I’ve done some sort of horrible damage or if there’s anything to look out for when I take off the covers.

    Also developed a problem shifting gears. But I think that’s a separate issue with the selector spring.
  2. pierodn


    Nov 10, 2012
    The oil is into the sump.
    Start the engine and it will come back in the tank.
  3. PopsRacer


    Aug 12, 2018
    So, it just essentially accumulates all the oil in the case?
  4. kommando


    May 7, 2005
    Possibly but you need to drain the sump to be sure, if the sump is clear ie only 200cc of oil then the missing oil could have been sent up past the rings by the higher internal crankcase pressure and out the exhaust.
    jerrykap likes this.
  5. texasSlick

    texasSlick VIP MEMBER

    Jan 2, 2013
    Try to slowly kick over the engine. If there is excessive resistance, the oil is hydro locking the engine, then drain the sump.

    If normal resistance, do what Pierro says.

    The sump can hold about a quart of oil before it hydro locks. The entire normal oil tank level, 2 quarts, can accumulate in the sump.

    PopsRacer likes this.
  6. mdt-son


    Jan 19, 2012

    .... provided the engine wasn't run for several days, and/or your oil pump leaks more than usual due to wear. The amount of leakage can be greatly reduced by restoring the oil pump clearances and applying a few other tricks.

    It's advisable to restore the engine breather, even if it doesn't work as well as other breather types do.

  7. Bernhard


    Apr 20, 2011
  8. jerrykap

    jerrykap VIP MEMBER

    Jul 23, 2014
    I agree that your missing oil is probably in the sump. But before starting I would drain the sump 1st. If you get more than a a small cupful then you know your engine has what we call "wet sumped". I've seen engines started up with too much oil in the crankcase pump oil out from under the cylinders . Not recommended. So check 1st.

    [ puQUOTE="pierodn, post: 448546, member: 4615"]Hi.
    The oil is into the sump.
    Start the engine and it will come back in the tank.

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