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Oil Breather...what does it do?

Discussion in 'Engine & Transmission' started by emby, Dec 12, 2009.

  1. Joel

    Joel New Member

    Messages:
    120
    Location:
    Northern Rivers NSW
    You got it in one there Necro, high CR motors pulling big revs usually leak badly due to the high pressure in the case and rocker covers so venting it more equally helps eliminate the problem


    give that man a cigar :cool:,
    breather boxes work well when they're hooked up right, the one in pics above isnt.
    i see it all the time, people fit them like that then moan and complain cos there engine still leaks oil out the rockers and starts pumping oil out the crank pulley as well

    As Terry spotted theres no way for the case to vent any blowby and the pressures caused from the bottom end doing its thing so it starts to leak past the rocker cover gaskets and past the oil slinger on the crank

    for the breather boxes like that to work a second breather hose off the oil filler needs to vent eitther into the air cleaner as intended or into the atmo via a little PCV pod filter
    most people run the breather box drain back into the case where the stock fuel pump goes and have the standard oil filler PCV hose into the aircleaner
     
    Last edited: Dec 20, 2009
  2. kommodius

    kommodius Active Member

    :wtf:

    My understanding of the engine above is that it was built by a very respected builder.
    I've seen it, heard it and inspected my pristine driveway after it's been for a visit.
    No sign of oil leaks even after the fairly strenuous climb from its home to my house on the hill.

    Ray & da Boyz
     
  3. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    Yep mine works great, built by one of the best engine builders in the country,
    Dont know many people who have built an engine 20 years ago, drove from Adelaide to Brisbane,( a couple of times) drag raced it and drove it home, also the same car has been to Sydney and Melbourne a few times, always driven NEVER trailered, always drag raced.

    SO I guess he knows what he is doing???????


    Forgot to add, My builder must know something as its done over 1200 miles and not an oil leak to be found ?????

    Dave
     
    Last edited: Dec 20, 2009
  4. Joel

    Joel New Member

    Messages:
    120
    Location:
    Northern Rivers NSW
    well if it stays leak free half your luck
    but if it starts leaking especially from the crank pulley you;ll know what the culprit is
     
  5. kombikid76

    kombikid76 New Member

    Messages:
    652
    Location:
    sunny sydney
    kommodius and Split 1 thats all well and good but the fact is your crankcase is not vented, you are providing advice which is wrong.

    Because of combustion blow by (gases blowing past piston rings during combustion) you need to vent your crankcase to the atmosphere.

    higher performance engines tend to run higher compression ratios leading to more blow by as joel mentioned hence needing larger venting capacity.

    ideally you should be running a positive crankcase ventilation (pcv) setup like all production cars but for some reason people are terrified of introducting small amounts of combusted gases into the intake (dont want to dirty their bling intakes i suspect!) or their intake setup doesnt allow it. The alternative is just vent straight to the atmosphere, usually through a catch can or at least a filter.


    In anycase if you are not venting your crankcase you, in theory, could pressurise it upto the pressure that gases reach in the combustion chamber, but you will blow past oil seals well before then, giving you a nice oil leak.

    The stock system is well designed and i imagine would be sufficent for all but the most high performance engines (undrivable on the street sort of performance) but the potential bling factor is certainly there.


    crankcases need to be vented to the intake or atmopshere at least, this becomes increasinly important as engines wear and the level of blowby increases.
     
  6. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    All I will say is on forums there are a lot of " experts".
    Proof is in the pudding.

    Dave
     
  7. kombikid76

    kombikid76 New Member

    Messages:
    652
    Location:
    sunny sydney

    certainly seems to be the case, perhaps you could tell us how your system is venting or why it doesnt need to vent?

    or is it working just because it does?
     
  8. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    If anyone would actually take the time to know the system I am using instead of just looking at a picture and making comments like "it wont work" "it will leak" and "your crankcase is not vented" they would know the ally box has a gap around the lid,(therefore it can vent) .Inside the box it has baffles and a filter.
    Proof is in the pudding, too many experts.

    Dave
     
    Last edited: Dec 22, 2009
  9. kombikid76

    kombikid76 New Member

    Messages:
    652
    Location:
    sunny sydney
    so your system is vented and filtered, sounds perfect to me.....

    maybe YOU could provide a bit of detail on YOUR system next time, could save a lot of time and face.
     
  10. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    Or people could ask instead of telling people they are doing things wrong????

    Dave
     
  11. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    Thats the problem Andrew, too many experts, they just look at a picture and say it wont work.
    If only people would get their facts right first a lot of dodgy info would not be posted on forums


    Dave
     
    Last edited: Dec 24, 2009
  12. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    And you know that Dave(B4) has "been there done that".
    We also fitted a stainless pot scrubber under the plate so the foam doesnt block up the inlet holes.
    I did have new Dyno covers but the quality isnt the same as the old school stuff.

    Dave
     
  13. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,368
    Location:
    Mannum South Australia
    Thanks for sorting that, now a question, are these alloy vented covers available for type2/4 engines. My engine currently has a breather inlet on the oil filler cap that goes to the clean air side of the cyclone air filter and the crankcase breather box is vented to 3 places in the air intake. It certainly cut down the oil leaks but in the new engine I would like to include rocker box breather to not only even out the pressures but to vent any moisture and fuel contaminants. I find the breather hose into the cross over air intake pipe a god send, no need for flash lube, the oil vapours from the crankcase are doing a fine job, the harder it revs the greater the crankcase air circulation and the more oil mist into the air, and much less oil on the outside, laughing

    T1 Terry
     
  14. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    You buy the covers and get the outlets welded to the covers, after drilling a hole in them first.
    I havent seen any ready made.

    These are the bolt in tubes

    http://www.csp-shop.de/products/13189b.html

    Or bottom of this page

    http://www.vwheritage.com/ssp/Engine-Parts/Heads-Rocker-Cover/?templateID=ssp

    Or you can by Earls type weld in ones and then have the female Earls type fitting on the hose if you dont want jubilee clips

    You can use the standard cover and fit the fitting to them
    Berg makes them for type 1 but you could do your own


    http://www.geneberg.com/product_inf...d=360&osCsid=08af7c8c84f8e81a0fc475fd5f4ee0c4


    Or some more, sure you would be able to get them over here.
    I went to a speed shop, V8 ect and bought the weld in ones

    Dave
     
    Last edited: Dec 24, 2009
  15. T1 Terry

    T1 Terry Well-Known Member

    Messages:
    1,368
    Location:
    Mannum South Australia
    Thanks Dave,
    I was keen on the look of the bolt on idea and a lot of engine tin ware is made from 2 sections pressed together with a layer of plastic in between for sound deadening. This type tinware always leaks if it's welded. Tin sumps etc are made this way but i don't know if vw did it on the type 2/4 engine rocker covers.

    T1 Terry
     
  16. Joel

    Joel New Member

    Messages:
    120
    Location:
    Northern Rivers NSW
    well you can exclude me from your little $h!t slinging match cheif cos id been running one for over 4 years before i stopped running VW engines

    [​IMG]

    i've put alot of time, effort and $$ into various high performance vw engines i've built over the years so you tend to learn how stuff works :rolleyes:

    i might add mines a bugpack one not a made in taiwan empi thing which probbaly only breathes around the top due to a lack of sealing
     
    Last edited: Dec 27, 2009
  17. Necro

    Necro Active Member

    Messages:
    2,626
    Location:
    Victoria
    I searched high and low with my google and lo and behold...

    I am back where I started....

    That's some spooky shit right there....:eek:
     
  18. Split 1

    Split 1 New Member

    Messages:
    7,037
    Location:
    Adelaide
    And still not an oil leak to be found, amazing my engine builder actually knows what he's talking about??

    Dave
     

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