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Oil drip from V35C air filter box

Discussion in 'Small Block' started by IceBlue, Jun 14, 2019.

  1. IceBlue

    IceBlue Tuned and Synch'ed

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    Never seen this before on my other SB's (7) - it seems like the engine constantly is pushing oil into the breather box, which on this model is a combination of the oil breather separation box and the air box. After each ride, oil is dripping out the air box drain.

    Any ideas? I have a V50/III with the same breather/air box, and no drip at all. Seems like the oil mist coming from the cylinder heads aren't drain fast enough by the oil return drain to the sump.

    Ciao
    Brian
     
    Last edited: Jun 14, 2019
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Either oil is over filled, or the rings are bad causing excessive crankcase pressure.
     
  3. IceBlue

    IceBlue Tuned and Synch'ed

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    Thanks John!
    Oil is spot on, and your other suggestion, is what i fear although the bike only has 16.000 km on the clock and purrs like a kitten. (hopefully not 116.000) although there are indications to that fact…(a very dirty sump now cleaned out).
     
  4. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    A leak down test can tell you if the rings are OK or not. Also it is not uncommon for the full mark to be over full. It is common for a Guzzi engine to push out some oil until it reaches a point between full and add. Adding more oil when below the full mark just results in more oil being pushed out.
     
  5. IceBlue

    IceBlue Tuned and Synch'ed

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    Thanks!:)
     
  6. IceBlue

    IceBlue Tuned and Synch'ed

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    Hi John
    Did a leak down test. Left cylinder 20%. Right cylinder 10%. Lifted both cylinders yesterday. Right cylinder looks like it's been doing very few km, perhaps true to the 15.000 the clock shows. The left cylinder has done more, There are wear edges from the rings in the top and bottom of the cylinder. However - 20% seems in the green zone of the leak down tester, or how are your take on this?
     
  7. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    The % isn't as important as where the leak is occurring. When doing leak down, I listen to find where the air is escaping. If it is past the rings, that can contribute to high crankcase pressure that can cause oil to escape to the airbox. Conversely if from teh valves, time for valve work. That said, it never makes sense to just do valves. If you fis the valve issue, you will just get higher compression on used rings which will develope an issue soon. That is why valves and rings should be done at the same time.
     
  8. IceBlue

    IceBlue Tuned and Synch'ed

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    I did a valve leak test on the worn cylinder when I lifted the head. It had a slight leak in the intake valve. I seated the valve grinding it with fine grinding paste, which did the trick, so I now know that the leaking here is from the rings. As this cylinder/piston seems worn considerably more than the right cylinder, I'm thinking of replacing it. This cylinder is the one shooting most of the oil out the breathing tube too. The right cylinder only did a couple of drops and the left almost filled a 10" tube on a 5 mile trip. I gather that's more that the return tube in the breather box can handle, hense the dripping out the drain from the filter box. This is funny too, the cylinder heads should shoot an equal amount of oil due to crank case pressure. Checked the oil return drain on both cylinders and heads. No obstruction at all...
     
  9. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Looks like you have found the cause.
     
  10. IceBlue

    IceBlue Tuned and Synch'ed

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    Again thank you for your input and guidance John!
     

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