AGG - Breather Valve Leak / Blow-by?

Discussion in '8-valve' started by bmouthboyo, Jan 4, 2019.

  1. bmouthboyo Forum Member

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    Hi Guys,

    I have a 140K MK3 GTI AGG engine that I recently installed into my VW T25 campervan. Great conversion and enjoying the torque it offers.

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    I noticed after a few hundred miles of varied driving, including recently high RPM motorway driving (3200 @ 70, up to 5000+ when beasting it) that I have some oil leaking from what I think is the plastic breather valve on top of the rocker cover.

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    I am fairly sure the leak is from here as the oil is more 'creamy' like the rest of the breather system given the oil has only done about 500 miles, and the oil managed to get onto the throttle body housing which a leaking rocker gasket wouldn't manage.

    I think the oil has come out of the small hole on the rear underside of the breather valve / connector. Is this a pressure release feature? Can I just block it up? Why would oil come out of this?

    Not sure what could have caused this but from what I read and having owned a MK3 GTI years ago I think oil working its way around this breather system and back to the intake is a common issue, however never experienced this kinda oil leak before and assumed any oil would be vacuumed back to the intake side.

    I am toying with idea of a catch can, but have read people saying venting to air is not ideal as the intake pressure on the breather system is good for seals etc. Can anyone recommend the best solution for a catch can setup in my situation?

    Any advice appreciated, thanks.
     
  2. Tristan Forum Junkie

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    Don't block it, replace it. They're available in the aftermarket and cheap . I put one on my AGG engined mk2 recently.
     
  3. bmouthboyo Forum Member

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    So is the saucer breather faulty? Is that little hole not standard?
     
  4. Tristan Forum Junkie

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    I don't know if it is, I suspect it's there to let the diaphragm move, but if oil is dripping out it, it must be letting oil past the valve.
     
  5. rubjonny

    rubjonny Administrator Admin

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    if oil is leaking out of the bottom of the PCV itself that suggests to me internal diaphragm is holed, looking at the pics I think top will unclip easily if so pop it off and take a look
     
  6. bmouthboyo Forum Member

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    Out of curiosity does the outlet from the rocker cover on the breather system vacuum or blow?
     
  7. Tristan Forum Junkie

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    It should blow into the flying saucer, same as the crankcase breather.
     

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