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Valve Cover Breather Question

Discussion in 'The Garage' started by mattcorleone, Jul 27, 2004.

  1. mattcorleone

    mattcorleone Registered Member

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    Hey guys, question on a Valve Cover Breather... can someone explain it's purpose (obviously it is to vent the engine at some point when it needs to vented - high RPM's?). I assume mine is hooked up factory style with the hose going into the air cleaner housing. What sprung this question is that there is some oil in my air cleaner assembly blown in from the breather. Is this normal? Thanks!
     
  2. rcpilot

    rcpilot 1/2 ton status

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    Have you checked your PVC valve?? If its plugged then I believe you can get some oil up there... also on the breather side there should be a filter of some sort..it's usually located on a stock set up in the air cleaner housing...
     
  3. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    Are you talking about dripping with oil, or just kind of a film? I think there is always going to be at least a little film.
     
  4. backcountry

    backcountry 1/2 ton status

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    The breather allows the bad gasses to exit and/or fresh air to replace it. It also helps with condensation.

    I have a 1973 that requires no smog. However, I leave my PVC valve in on one valve cover and run it to my intake manifold. I have a K&N breather in the opposite valve cover.

    Some engines more so than others do give off excessive oil vapors and depending on where your PVC valve runs will show signs of oil. A small amount of oil is normal though. Engines that are badly worn can produce quite a bit more oil though.
    /forums/images/graemlins/peace.gif
     
  5. diesel4me

    diesel4me 1 ton status Premium Member

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    The breather in the air cleaner is suppossed to let fresh air into the crankcase,but when the engine starts getting old and lots of blowby,the flow sometimes reverses,pulling oil vapors into the carb,and clogging the air filter and filling up the base of the air cleaner with motor oil. The 400 small block in my plow truck did that pretty badly,so I moved the "bowtie" breather thing from the air cleaner to the front of the radiator support with a peice of heater hose,to keep my air filter from getting oil soaked. New rings and a genral rebuild are in the cards if I plan on using the engine more,but I only plow the driveway and go to the landfill with it,doesnt see many miles anyway-- /forums/images/graemlins/tongue.gif
     
  6. mattcorleone

    mattcorleone Registered Member

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    [ QUOTE ]
    Are you talking about dripping with oil, or just kind of a film? I think there is always going to be at least a little film.

    [/ QUOTE ]

    The hose runs from my pside valve cover up to the air cleaner assembly. There is a little breather filter there in the air cleaner assembly where the hose comes in. It is pretty oil soaked and there is a bit of oil in the bottom of the air cleaner pan right under it... I'd say about a teaspoons worth if I had to guess, maybe not that much. I'll have to poke around under there a little more and check out the PCV... I haven't had the truck long and I can't visualize under there yet while I'm here sitting at work... plus it's been quite a while since I've messed around with a carbuerated engine!!! Thanks!
     

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