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[dublin.jd]

Anyway I'm off to bed, hopefully I can sleep after the ridiculing I've just underwent! (joke)
Thanks

Remember I said to pretend that my car was running as designed? Ie. Perfect!
Some people can't get passed that. And that narrows their train of thought and we all get nowhere.
Anyway I'll be back 2moro for more abuse  good night

[05omegav6]

Should actually be minimal pressure in the crank case, certainly what air is in there will move around as the cylinders rise and fall, but there are six of them and as at any one moment an equal number are moving in opposite directions the air will simply move around

Any significant blow by will be apparent from a lack of compression and/or noise from badly worn components.

Factor in the direct connection to the air intake, and it becomes almost impossible for the crank case to have anything other than negative pressure...

[chrisgixer]

Would negative pressur in crankcase not suck more blow by gases in, therefore affecting performance?
Again just a question. It makes more sense to me for it to be at equal/atmospheric pressure.

Assuming the car is running as designed. No issues.

Also assume that crank cases should run at atmospheric pressure as you say



Now disconnect the breathers. The crank case can not possibly now be at the desired pressure. Can it!

Dear god. Can I have some strength please.

[05omegav6]

Try this...



 

[omega2018]

im actually a bit shocked by this thread.  its like some feeding frenzy in a nature program.  lords and barons ganging up on a junior. some people should be ashamed.

ive not read all of the huge number of posts since i last posted ITS TOO BORING but there is a lot of crap being spoken here. crankcase will be under positive pressure that is why there is a breather system.  as mentioned just open the oil filler cap and feel it with your hand. anyway a prv valve would not let air in it only opens to release pressure thats why its called a pressure relief VALVE. so why keep asking if the op wants to let air in his system he doesnt. some one said 5 quid on a prv would be better spent on a scratch card. yes if it was a winning card.  no if at some point in the cars life if your theories about blocked breathers being the cause are correct the gaskets will leak due to crankcase air pressure pushing oil thru. how much does that cost to fix? if a prv is fitted the pressure will be vented through the oil filler cap and the gasket will be saved giving u time to clean the breathers. you'll know they need doing cos there will be stains on the bright yellow by the prv exit.

Type the letters shown in the picture:
How many road wheels are fitted to the car (digit, not spelled out)?:
What colour is the indicator on European cars, also a fruit?:

[chrisgixer]

If some people are that appalled perhaps they shouldn't join in in the exact same vain.

Just saying.

They guy has changed his theory half a dozen times and displays the exact same sarcasm nobody else is allowed.

Anyway, your telling me there's no vacuum from the plenum is that correct?  How does the intake air get into the cylinders then I wonder.

6,500 rpm to tickover and there is no vacuum in the plenum? Do I understand you correctly?

[05omegav6]

Was just trying to find my copy of the Vauxhall College guide to the Omega... must be in the garage

Replies 12 and 13 here are noteworthy...

http://oldsite.omegaowners.com//forum/YaBB.pl?num=1306257481/all

And this should debunk a few myths as well...

http://www.google.co.uk/url?sa=t&rct=j&q=y32se%20breather%20system&source=web&cd=2&ved=0CCsQFjAB&url=http%3A%2F%2Fwww.106rallye.co.uk%2Fmembers%2Fdynofiend%2Fbreathersystems.pdf&ei=GHTgUoOfN5T20gXW8oGoBg&usg=AFQjCNEAeZemBNjN0wzVncL9rfHuh3U2dw&bvm=bv.59568121,d.d2k

[omega2018]

6,500 rpm to tickover and there is no vacuum in the plenum? Do I understand you correctly?

no you dont understand me read my post "crankcase will be under positive pressure". read the taxi experts article on blow by.

now youve got me wrestling with pigs.  im not going to argue stupid points like is there a vacuum in the plenum THE CRANKCASE WILL BE UNDER POSITIVE PRESSURE.  look it up or just stick your mouth over the oil filler and get someone to rev the car.  in gear.   forward preferred but reverse will do.


Type the letters shown in the picture:
What do the letters OOF (our forums initials) stand for? See image at top left of page.:
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[omega2018]

ah at least i am not getting that stupid

Type the letters shown in the picture:
What do the letters OOF (our forums initials) stand for? See image at top left of page.:
What colour is the indicator on European cars, also a fruit?:

any more thank you at least for that.

[chrisgixer]

It cirtainly will be if the breathers are disconnected.

[Entwood]

Simple laws of physics now .... how can any system connected to a correctly working vacuum source (breather system) be considered to be "under positive pressure" ?? 

The whole crankcase is one "void".. it does not have compartments at differing pressures. It is a "sealed" void by the oil filler cap (look at the seals on the cap) and the dip stick (again, look at at the seals on the dip stick) and all the other seals/gaskets and goo.

The breather system extracts air and holds the "void" at a slight negative pressure - WHILE THE VOID IS SEALED - if you then remove the oil filler the void is no longer sealed, the negative pressure disappears (the breather system cannot evacuate the earths atmosphere) and any blowby gases, or the movement of the cylinders, will cause air movement through the bloody big hole that is the oil filler cap.

fluid laws/theory are extremely simple .. until you try and get a fluid to push against nothing .. which it cannot do ... gas (and any other fluid) can ONLY have pressure in a SEALED system.... but a vacuum can suck in a non-sealed system ... exactly as your hoover works !!  it moves air by creating a vacuum (that is rapidly filled) ..... and that's what the breathers do ... they "hoover" the crank case .....

If the void is sealed, but the vacuum is not present, then with the engine running a positive pressure will build up, that is what blows the gaskets.

[omega2018]

this is just getting mad

so its a vacuum until you open the oil filler cap then it miraculously becomes positive pressure? and it has a fancy name,  fluid theory.  perhaps its like that cat in the box you never know what it is until you open the filler cap. schrodingers crankcase.

there is no vacuum anywhere on an omega unless you left your coffee flask in the boot.  correction there is one on a tiny number of migs, its a few cm under the roof and 1m above the drivers seat.  only on the noisy ones though. 

instead there is slightly above normal air pressure in the crankcase and slightly below in the air intake.  the breather connects these two.  im not posting on this again it has changed from boring to irritating and boring at the same time.

[chrisgixer]

Good, now can we get on!

There's are numerous uses for vacuum on the omega. ALL of which use the vacuum in the plenum.
1) Servo assisted brakes.
Runs of the black pipe that exits the right side of the plenum, curves round the back under the breather tubes and attaches to the brake servo. I know this is vacuum operated because if/when the clip that holds it to the ac pipe wears through it, it causes an air leak/hissing/poor tick over/maf error code. Plus my brakes work with an assisted pedal. You may have noticed this, although maybe not.

2) multi rams.
Waisting my breath here for the hard of understanding but the multi rams are vacuum
Operated from the t to brake pipes at the back of the engine on the v6.

3) breathers. (Sigh)
Runs off the same lump of engine as the brake servo and multi rams. (So there is defo vacuum, right? )

4) the inlet plenum to the engine
6 pistons (or 4 for effeminate types )pumping up and down. The down stroke is a vacuum or no fuel air mixture would get in there, it's basic principal of the combustion engine. Times this by 6 and you have enough vacuum to feed a 3litre engine, brake servo/multi rams/breathers.

It's also enough to draw in enough air to throw maf and fuel trim errors if there is a leak from a split breather pipe to plenum as I often see on my drive when members have issues with grumpy tick over and fault codes.

Now, it's almost 2pm which means its day time. If your the type to then deliberately post up that it's actually night time where I am,or that there is no vacuum on the omega, then go ahead.

Because anything under normal atmospheric pressure, is indeed a vacuum. However slight. 

[omega2018]

Because anything under normal atmospheric pressure, is indeed a vacuum. However slight. 

vacuum
ˈvakjʊəm/
noun
noun: vacuum; plural noun: vacua; plural noun: vacuums

1.
a space entirely devoid of matter.
synonyms:   empty space, emptiness, void, nothingness, vacuity, vacancy;
2.
a vacuum cleaner.
synonyms:   vacuum cleaner;


verb
verb: vacuum; 3rd person present: vacuums; past tense: vacuumed; past participle: vacuumed; gerund or present participle: vacuuming

1.
clean with a vacuum cleaner.
"the room needs to be vacuumed"
synonyms:   vacuum-clean;

[chrisgixer]

Getting warmer