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I always had it in my mind that it was both ways... i.e. when the crank is pressurised, say from a clogged pcv valve or cactus rings, and the pressure pushes oil up past the rings into the combustion chamber- or, as per your above statement...Quote:
Originally Posted by tinkerbell
Also I think the orignal topic starter is suggesting that the oil itself is getting past the Rings in to the combustion and again I question that.
People are on different wave lengths.
Some are thinking the affects of blow by from combustion to crankcase other people are thinking effects of blow by from crankcase to combustion.
I always thought it was oil getting direcly into the chamber via going past the piston rings.Quote:
Originally Posted by tinkerbell
Never thought about it happenning the other way round. :(
sounds far-fetched to me... each piston upstroke has higher combustion chamber pressure than crankcase pressure (ie compression of A/F or pushing hot exhaust out) so as to have little to no chance of getting past the rings...Quote:
Originally Posted by ginganggooly
http://www.bobistheoilguy.com/blowby.html
I know with my car, it suddenly developed a huge oil consumption problem and started belching out copious amount of blue smoke.
Changed PCV valve and problem was solved. DynoDave and I put it down to the crank case pressurising and pushing oil up past the rings... It seems more or less logical to me- bearing in mind that the rings are over 260k km old....
hmzszs... i think im on the same page as tinkQuote:
Originally Posted by JasonGilholme
i think you could be wrong there.. correct me here but this is what makes sense to me
Its compressed air esacping into the crank case on the ignition stroke and not oil sepping into the combustion chamber.... Air is much much smaller than oil in particle size..
That is why you do a compression test.. u test how much pressure it hold.. if it looses pressure means the pressure is going into crankcase...... the pressure theyere will be the unburnt stuff call blow by....
And the word also implies:
Air Blow By Piston ring
yes, if the crank case is sealed, this maybe one outcome...Quote:
Originally Posted by ginganggooly
shit now im confussed!! ok i havnt been on here for a few days so my appoligies.
when u take the oil cap off there is a massive amount of air rushing out?? worse than i have seen on any other car. it has no oil leaks but has rather high oil consuption?? but doesnt blow excessive smoke if at all.
its has 75000klms but has been track by the previous owner and there for not had an ezy life.
do u guys recommend i get a compression test to see whats up?
i cant get this fixed till i get my box and clutch done anyway but i am trying to work out what it is:confused:
that what we are trying to tell you for the last 20 posts..Quote:
Originally Posted by JasonGilholme
Air is small than liquid... you will be loosing Compression air long before the oil seeping through
Yeah but noone ever directly said that the compression air was pushing oil vapour from the crank case though the PCV system into the IM and then into the chamber did they.
it makes sense to me know lol. sorry. :)
Lots of air rushing out of the oil cap is a symptom of blow-byQuote:
Originally Posted by hi comp
This will cause excesive oil consumption via the PCV valve...
It could also be valve guides or both...
If really depends on how hard a life the thing had before you purchased it.
Hi Comp, You need to:Quote:
Originally Posted by hi comp
1. Test your compression
2. Check to see if your PCV valve is working ok and not stuck. You can simply take it out, shake it up and down and you 'should' hear the little ball move up and down.
3. Make sure you PCV system is plumbed up correctly
Also a lot of people have their Oil Catch Can plumbed up incorrectly. I have got mine hooked up between the PCV valve and the Intake manifold. There it catches the oil vapours after the crankcase, but before it enters the Intake Manifold.
Photo for your reference courtesy of Ben:
http://i13.photobucket.com/albums/a2...d_pcv_657b.gif