308 what is the purpose of the crank case vent hose | FerrariChat
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308 what is the purpose of the crank case vent hose

Discussion in '308/328' started by isetta308, Mar 1, 2010.

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  1. isetta308

    isetta308 Rookie

    Jan 4, 2010
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    #1 isetta308, Mar 1, 2010
    Last edited: Mar 1, 2010
    Hey guys, what is the purpose of the vent hose that is attached to the drivers side end of the rear head and goes to the top rear bell housing. The hole in the bell housing goes no where but to the open space of the fly wheel and clutch.

    Is this hose venting oiley vapors/crank case vapors into the clutch area?

    If this is a crank case vent, should it be vented to the carbs or a filter installed on it like the old chevy valve covers did?
     
  2. st@ven

    st@ven F1 Rookie

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    #2 st@ven, Mar 1, 2010
    Last edited: Mar 1, 2010
    pictures? I don't remember a hose like this on mine..
     
  3. Newman

    Newman F1 World Champ
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    #3 Newman, Mar 1, 2010
    It vents pressure to the valve cover then the pipe from both valve covers vent to the air filter through the connecting pipe between the two covers. The lower breather also ties into this and has an oil seperator can. The euro car has a similar setup but uses a bolt on adapter than goes where the US spec cam airpump drive comes out. Different head euro to US.
     
  4. 308 GTB

    308 GTB F1 World Champ
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    #4 308 GTB, Mar 1, 2010
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  5. st@ven

    st@ven F1 Rookie

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    #5 st@ven, Mar 1, 2010
    yes i know but the op stated that his hose goes through a hole in the belhousing..
     
  6. isetta308

    isetta308 Rookie

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    #6 isetta308, Mar 1, 2010
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  7. gonzo350

    gonzo350 Karting

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    #7 gonzo350, Mar 1, 2010
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  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #8 Steve Magnusson, Mar 1, 2010
    Vents the gearbox/transfer gear area. On the earlier carbed 308, it (the 11 o'clock end) was just left open to the atmosphere, but emission restrictions were tightened.
     
  9. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #9 Steve Magnusson, Mar 1, 2010
    Last edited: Mar 1, 2010
    Even though the hose fitting is located on the intermediate plate, I believe it communicates (pneumatically) into the engine crankcase, not the bell housing -- anyone got a jpeg of the intermediate plate on the engine side?
     
  10. gonzo350

    gonzo350 Karting

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    #10 gonzo350, Mar 1, 2010
    Makes perfect sense...but wouldn't the large hole just above the transfer case cover provide plent of ventilation?
     
  11. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #11 Steve Magnusson, Mar 1, 2010
    No, that large hole vents into the (dry) clutch area only, the gearbox/transfer case internal (wet) areas are not connected to the large hole.
     
  12. ramosel

    ramosel Formula 3

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    #12 ramosel, Mar 1, 2010
    Last edited by a moderator: Sep 7, 2017
    Hopefully this shows it clearly. Unfortunately I can seem to find a pic of the other side while I had it off. The pipe definitely is on the intermediate plate. It does not protude into the clutch housing so one can only surmise it does, as Steve suggested, vent into the motor area. The second pic show the area it would vent to, a chamber above the crank.

    Rick
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  13. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
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    #13 Steve Magnusson, Mar 1, 2010
    Thanks Rick -- that shows it clearly.
     
  14. CliffBeer

    CliffBeer Formula 3

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    #14 CliffBeer, Mar 1, 2010
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    Both sides of the piston stroke need venting (in addition to the actual exhaust obviously), particularly where there's only oil galleries and water cooling passageways between head and block. However, in engines where there are open spaces into the valvetrain area of the head - perhaps where there's a valve lifter for example - the block venting can be accomplished through the head venting so you don't always see separate block venting. In any case, good to keep these lines open and flowing as positive pressure from failed venting can blow out seals pretty quickly.
     
  15. isetta308

    isetta308 Rookie

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    #15 isetta308, Mar 2, 2010
    WOW, thanks for the response. Your pics really clear things up. I have an oil leak from the rear seal and wanted to make sure that it wasnt blown due to crank case preasure (thats the reason for the questions).

    On a side note though. I pulled all of the pcv hoses, oil seperator and this rear head crank case hose and when I started the motor to check for oil leaks and to look for any vapor venting from these areas. The one thing I noticed that there was no venting of any vapors from the pcv openings. I even opened the oil fill cap and noticed the atmosphere inside was clear and not oiley.

    I am used to American V/8 engines producing large amounts of crank case vapor, so much so that it left a large amount of oil every where on the outside of the engine. Is it possible that this engine is so tight that it does not produce or produces very little crank case vapor?
     
  16. ramosel

    ramosel Formula 3

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    #16 ramosel, Mar 2, 2010
    When I got my car, it leaked and blew oil everywhere... we nicknamed it the "Enzo Valdez". Really, it was all just in the heads and the front main. The PO was a buddy and he agreed to back out the price of redoing the heads from the price of the car. While we had the heads off doing a full valve job/refresh we looked at the bearings on the bottom end, they looked good so then we did a leak-down at the block and even with 56K on it, all cylinders were right at 1% or less. I was surprised.

    So yeah, the bottom ends are pretty stout and tight on these little motors. Thats why I don't cringe too much when I see guys pumping them up.

    Rick
     
  17. isetta308

    isetta308 Rookie

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    #17 isetta308, Mar 2, 2010
    I am ready to remove the real main seal. Its really stuck in there, is there any special way to remove this. Do you just pry it out with a flat srcrew driver?
     
  18. st@ven

    st@ven F1 Rookie

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    #18 st@ven, Mar 2, 2010
    Last edited by a moderator: Sep 7, 2017
    This is the seal on the other side but the way is the same. Just drill a small hole and drive a screw in it. Now just pull it out
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  19. isetta308

    isetta308 Rookie

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    #19 isetta308, Mar 2, 2010
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