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[Grrrrrr]

There's a lot of talk about breather hoses on here and the implication of not cleaning them. I'm still not entirely sure why we need them other than the obvious answer (that they let the engine breathe) which kind of brings me to my question: what would happen if I just disconnected them and left them open to the atmosphere?

Presumably I'd lose some of the oil that is present as a mist in the crankcase cover. But how much and how fast? If it just means adding a bit of oil once a month, isn't that less hassle? Or do they do something else?

Mention it because I bought the current car nearly five months ago and have yet to find the time to get around to this job. Struggle to find time to sleep!

J

[feeutfo]

had some very similar questions my self a while ago.

The answers, i beleive, are that the plenum runs at a vacuum (and is where the vacuum system draws from) and the crankcase runs at positive pressure due to blow by gases from combustion. This pressure must release or blow a seal as we all know too well.

Trouble is, i think, atmospheric pressure is not enough to aid the engine case breath so the plenum sucks it out, in effect. And the engine burns off its own vapour, so the manufacturer doesnt have to find another way to deal with oil vapour escaping.

Afaik anyway. :-)

[Kaycee]

i too have wondered about this as i am getting on in years i have seen different crank case breathing yes its definatly needed but older engines used to have a pipe that came out of the crankcase pointing down into the air flow and this purged all the crankcase gases i know it was the emmisions into atmosphere that bought it about but if something could be rigged up to vent the crankase would stop seals going just my twopenorth

[Kevin Wood]

Firstly, the breather outlets on the intake system will cause a leak of unmetered air if they are left open, so they need to be connected to the crankcase or blocked.

Secondly, the crankcase breather system does 3 things that open breathers dont; it keeps the crank case at a slight vacuum relative to ambient pressure, it causes a flow of air through the crankcase during most driving conditions to purge it of combustion by-products and it ensures that all fumes from the crank case are burnt and not emitted to atmosphere.

Kevin

[Andy H]

Thirdly - it prevents the oily mist from fouling your engine bay and the fumes (mixture of exhaust gas and hydrocarbons) from escaping and entering the air intake of the cabin heater/climate control system

[Kevin Wood]

Thirdly - it prevents the oily mist from fouling your engine bay and the fumes (mixture of exhaust gas and hydrocarbons) from escaping and entering the air intake of the cabin heater/climate control system

Oh, yes. If removed, the pipes need to go to a catch tank, and then fed out under the car, or it'll make a real mess / smell.

No point in changing the current setup, IMHO. It works perfectly if it's cleaned out annually.

Kevin

[Grrrrrr]

Interesting. Interesting. So in short, we need a vacuum that doesn't pollute the environment ... although not too big a vacuum or presumably we'll start interfering with the air flow monitoring.

Alternatively, I could maybe rig up some junctions and suction pump arrangement that allows me to draw air though and suck petrol through the whole system to clean it all out at regular intervals. Then it'd be a ten minute job that I could do once a quarter or so.

Reckon there are possibilities here. Need to stare at the setup for a while and think through implications!

[Bionic]

No need to be afraid of it! The job is straightforward enough but you will probably lose a bit of skin. I have just done the job myself cos it was fully choked and it took just under a couple of hours, coffee time included so it really is that simple. Have alook in the maintenance guides and you will find a subject on how to proceed. Its what I used.
GudLuk

[Xplicit 2.0]

Ok, this has answered a few questions for me, good job i re attached mine then :S

The next thing is whats the internal diameter of the small and large breather hoses on the X20XEV?
a. im really to lazy to de-choke them (small breather has no suction on it)
b. the pipes could do with replacing as they are starting to perish (the small hose has no spring back to it what so ever)

i was thinking of going with some blue silicone hoses but not sure on the diameters, and rather than just having 1 blue pipe, i thought i would replace both the large and the small breather at the same time.

Cheers,

Sean

[TheBoy]

As peeps have said - stick to the genuine setup

If the car is regularly serviced with quality oil (certainly not castrol - that doesn't suit Omega), the breathers stay pretty clear.  That said, I still clean mine every summer, more as a check rather than they need doing...

[Xplicit 2.0]

ok, all im wanting to do though is just change the hoses... that cant really make much of an effect surely? as i said the small breather hose is really perished and could do with replacing, and i would have thought silicone hoses would last longer

[TheBoy]

ok, all im wanting to do though is just change the hoses... that cant really make much of an effect surely? as i said the small breather hose is really perished and could do with replacing, and i would have thought silicone hoses would last longer

I was answering OP. Of course its fine to replace the pipework with new pipes.

They are shaped iirc, so pattern will be hard to find, so good ones from a breaker, or brand new GM.  Who wants blue pipework under their bonnet?

[Xplicit 2.0]

haha, well without being rude or causing offence, im a youngster that still likes his modified cars and with every mod, its gotta start somewhere, and what better than something sensible (rather than my usual exhaust and inductions kits) 

PS also my apologies for assuming your first response was at me 

[RossMk2]

On mine as its a conversion the breather pipes on the intake have been blocked and the breather box on side of head just has a pipe going to the underside of the car to expell gases that way. Its done like this as the intake has been turned 180deg. so that all the electrics are on the bulk head in the astra. I would much rather have it as standard but the GM pipes just wouldnt make it to the other side of engine, im thinking of one day soon sourcing some pipes (might be blue who knows) so that i can rig it back up again. But i have never seen how there were when from factory, which would probably help! hehe

[TheBoy]

haha, well without being rude or causing offence, im a youngster that still likes his modified cars and with every mod, its gotta start somewhere, and what better than something sensible (rather than my usual exhaust and inductions kits) 

PS also my apologies for assuming your first response was at me 

Its my age

Seriously, I seem to recall they are shaped pipes. Risk of using straight tubing is kinking, thus blocking. This usually has the effect of blowing the cam cover gaskets.