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bigpaulo

Oil Breather

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Yo

So, ever since i put the holley carby and changed to a small air filter, that pipe on the back of the rocker cover that usually goes into the bottom of the air cleaner has just been flopping about all over the engine bay... i never knew what else to with it.

I changed my oil the other week and noticed a fair bit of sludge in the bottom, thought ive been sucking years of crap in through that open pipe.

Can you fit those little oil breathers onto the back of the rocker cover there? Any recommendations? Ive never really looked into them before. Also, where that pipe connects on the rocker cover is a right angle fitting, can i change this to vertical so if i put a breather on it'll sit upright?

Cheers y'all!

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I'm a little bias as I work with steel for a living (and I did make it) but I like this- used the charcoal canister as an oil catch can with drain and scourer pads. Don't know exactly how it would go with a boys in blue check but I have it plumbed mine so it looks like it goes back into the engine(although technically speaking that's not how the charcoal canister operates anyway) at least there is a factory charcoal canister in the engine bay.

20151223_142238_zpsjp6e5mkw.jpg

 

Details of how I made it are in post #352 here http://www.ozfalcon.com.au/index.php?/topic/4428-solid-roller-cam-xe-spak/page-18  If your interested I can take pics of how I plumbed it up on the engine, I also drilled the bottom of my aftermarket aircleaner base to put a fitting on it that the hose you talk about that is just sitting lose can connect to.

I will give credit to Crazy though as I got my idea from what he did in the first place.

 

 

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Should be able to buy a straight PCV to get rid of the 90* one. Pop the old one out, and show it your local Spare Parts guru.  Usually, the pipe goes into the base of the carby, ( or inlet manifold ) to recover the fumes and get cleaner emissions. Catch cans work well.

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Oh wait hang on im a bit confused now. The circulation of air, does it go -->air cleaner-->rear rocker cover pipe-->pcv-->

 

Or

 

-->pcv-->rear pipe-->air cleaner-->

 

I hope this makes sense

Id draw a picture but im no picasso

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The second one.

 

The crankcase develops a positive pressure due to "blow-by" of combustion/exhaust gasses getting past the piston rings.

https://en.wikipedia.org/wiki/Crankcase_ventilation_system

 

the PCV is jsut a valve that lets gas flow OUT of the engine and not IN. It flows out, and is plumed into the intake, then burnt during normal combustion. Sometimes the crankcase is at a vacuum, Plumed into the manifold plenum, and sometimes it's at ambient pressure, plumed into the intake pipe between the air cleaner and the turbo/carb/throttle body.

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I was told the air flows from the aircleaner into the rocker cover, then out the pcv into the inlet manifold or catch can. If it is routed to a catch can to keep it legal you have a return line to the inlet manifold so the (hopefully) clean air re-enters the combustion chamber to be re-burnt.

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If you have a pcv valve in the rocker covers it will just vent fumes to atmosphere and will not (theoretically if the pcv is still functioning) let air back in. Is this bad? Yes if you get caught cause that's sorta against emission regs cause oily fummy air is bad for the environment. Is it bad for your engine. No not really. Its just venting the bad stuff and not sucking it back in.

 

Crazy is all over it in his description above, it shows the 2 ways that the bad stuff is dealt with, either way works.

 

So you either fit a catch can to stop all the fummy oil laden air that is currently just being vented to atmosphere, or you just run the tube down the back of the motor and lit it drip onto the road.

 

Old school drag racers used to run vent tubes from the rocker covers down into the headers as a primitive form of sucking the fumes out. The theory is that the exhaust gas speed passing by the tube creates a vacuum and that sucks the bad stuff out if the engine and into the exhaust. It worked and then vac pumps were invented and are much more efficient at creating vacuum and pulling the fummy oily air out.

 

So you can either fit a catch can or run the hose in either of the 2 ways crazy outlined above.

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Preferably you Don't run the line to the road. 1 car dripping minor amounts of blowby oil onto the road is of very little to no consequence. However, you get a large enough portion of people doing this, mixed into the people whom drive is oil leaks, and the next time it rains you get slippery roads and all of us (with the exception of a few P' platers) can agree that is no good.

 

The example you walk by is the example you set.

 

Now that's out of the way, Having the gasses plumed into the intake, even just the small pressure drop caused by the air filter, helps scavenge the gasses and reduces positive crankcase pressure. In turn reducing the risk of developing oil leaks.

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Yes crazy you are very right. Dripping oil onto the road way is bad. Please don't do it. Funny thing is my old xm coupe still has the walking cane fitted and it gets a bit huffy at times. Lucky I don't use it everyday.

 

edit, just realised there is probably a whole generation of people who don't know what a 'walking cane' is (in engine speak). Lucky they have google

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Yes crazy you are very right. Dripping oil onto the road way is bad. Please don't do it. Funny thing is my old xm coupe still has the walking cane fitted and it gets a bit huffy at times. Lucky I don't use it everyday.

 

 

edit, just realised there is probably a whole generation of people who don't know what a 'walking cane' is (in engine speak). Lucky they have google

 

My mate has an xp with a 170 that is a heavy breather ( full James Bond effect ) , the smoke was getting so bad that I ended up removing the road draft tube and replaced it with a pcv valve (machined up a little spacer in the tube hole and the pcv goes straight into it) and the plumbed it into the intake, stopped the blow by and stopped it dumping oil on the road

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I think we might be on the wrong path here... i have a pcv that is plumbed up and working fine, i dont have any intention to stuff around with that. I just wanted to do something about the pipe at the back of the rocker cover that lets air in.

Its all good ive figured out how to sort it, ill put a pick up when ive fixed it up.

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I thought the PCV was at the back...? Understand what you're saying, though. We just got carried away.... :P

Normal PCV's are just a small weight inside a tube, like a ball bearing or similar, it just lifts off it's seat to let the gas out, and gravity makes it fall back and seal. So, vitually no air will get back in.  It's the other end that you're worried about.......

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