Originally Posted by czar

When I asked was it serviceable, I mean are you able to remove the "mesh" from the can, clean or renew it and replace it, I guess not, so therefore it's non serviceable.

Originally Posted by DneprDave

From what I've read on these forums, the BSH oil catch can has a vertical baffle that forces the path of the crankcase vapors down from the inlet and then up to the can's outlet, giving the vapors a better chance to condense out. Not 100% efficient, but what is?

It will be nowhere near 100% efficient, as I've already mentioned it will at the very best only be 50% efficient at oil air separation, like all OCC's out there, it relies on a change of gas flow direction, and the addition of a baffle plate provides a further disruption of the gas flow, all of which slow the gas flow down sufficiently, to encourage the oil vapour particles to become to heavy to be suspended in the gas flow, and hence they drop out of suspension.

Regarding water vapor condensed out in the oil catch can. I understand that the water is condensed out of the crankcase gasses, from thermal dissipation due to the OCC's construction, normally Aluminum, and the gas flow speed, again have a read up on thermodynamics, and the gas law. but the water originally came from the engine, correct, from the effects of heat cycling, (sweating) you need to read up on thermodynamics! heat cycling just explains that it condenses out, not it's origin. The engine is the original source, from the effects of heat cycle (sweating) It is either coming from a bit of blow by from the rings or from the atmosphere, though atmospheric water vapor is probably a minor component as the engines are pretty air tight. You really need to understand the basics of the internal combustion engine, as you clearly have no idea!

The oil catch can isn't making water, Yes it does. it is just condensing the water out of the vapor coming from the engine as it flows through the oil catch can. Well done, your finally starting to understand, the bit you don't or won't believe, is that as the hot gasses enter your can, thermodynamic heat dissipation takes place faster in your can, than it ever does in the engine, and your OCC believe it or not, sweats, and hence produces it's own water vapour droplets. Better in the catch can than in the intercooler where it would be more difficult to remove. It would be less of a problem in the intercooler, as your intercooler is super heated from the compressed (squeezed) air, fed from your turbo charger, and the shear speed and heat of the air flow through the intercooler, will keep any moisture or oil particles suspended, to be carried through your intercooler.

Dave

Originally Posted by DneprDave

OK, the engine is the source of the water, through heat cycling but what is the origin of the water? From thermal heat/exchange dissipation, your engine starts off cold, yes ? as soon as your engine starts up, you immediately introduce heat, from the firing temperature within the cylinders, this is approximately 600-650º C and rotational friction, you now have intense heat acting on cold fluids, oil and water and the different metals used within the engines construction, everything heats up at different rates, this is simple thermodynamics, and each individual components properties has different acting thermal heat dissipation properties, and until your engines components, oil and water have reached their specific working temperature, then your engine will sweat, producing water vapour from the many different thermal heat dissipation properties, of the many different metals and fluids, producing water vapour droplets, remember that you now have intense heat + cold metals, cold fluids (oil/water) the oil and water are part of regulating the engine at a certain specified working temperature, but until that X working temperature is reached, the oil and water is still cooling even though the engine is going through it's first initial heating up cycle, and this produces sweating, in the same your body would, if I asked you to exercise wearing your winter coat in summer, you sweat yes ? where does your sweat (water droplets) come from ? they come from your body having a different temperature to the outside, also ever seen on a hot day, your ice cold bottle or can of beer produce water droplets on the outside ? this is simple heat exchange thermodynamics, sweating due to bringing to acting different temperatures together, cold beer on the inside, in a cold vessel (can or bottle) and a hot ambient temperature outside!

Once your engine is up to working temperature, then there is sufficient regulated (controlled) heat, to burn off the water vapour, from the initial cold start, on the other hand if you are a regular short distance, stop start driver, and your engine rarely gets to normal operating temperatures, then your engine will produce more water vapour, from partial heat cycles and rapid cooling. It has to come from somewhere. Heat cycling just explains how it condenses out. The only place I can think of is past the rings.

Dave

Originally Posted by DneprDave

Regarding water vapor condensed out in the oil catch can. I understand that the water is condensed out of the crankcase gasses, but the water originally came from the engine, heat cycling just explains that it condenses out, not it's origin. It is either coming from a bit of blow by from the rings or from the atmosphere, though atmospheric water vapor is probably a minor component as the engines are pretty air tight.



Dave

Originally Posted by DneprDave

Thank you for being patient with me, Czar.

OK, so a cold beer sweats because the temperature of the surface of the glass is below the dew point temperature. That water is condensed out of the air. I have noticed that when the humidity of the air is very low, a cold beer doesn't sweat.

Inside the crankcase, there is oil and air. Correct, but the air is a % of the wasted combustion gas, known as blow by, and turbulent air from the rotating mass. Once the engine reaches operating temperature, any water in the Contaminated air would be vaporized (burnt off) and pulled out through the PCV system. Now, if there is no other source of water vapor, the crankcase would be free of water and water vapor. Correct. The engine is shut down and allowed to cool. If water isn't being re-introduced from somewhere, there wouldn't be any water vapor in the crankcase to condense out on the cool metal parts inside. Yes there would, the heat dissipation properties of the different metals, especially the Aluminum engine block, cools a lot faster than say the oil, and this difference in heat exchanges, produces internal water vapour!

The crankcase is sealed from the outside by design. The only place I can see as a source of water vapor is in combustion gasses getting by the rings. Even in a brand new engine there will be some small amount of blow by, Yes there is and it's approximately 1-3% of the total swept volume. the oily water I get in my oil catch can sure smells burnt. It does, that's because the contents of the OCC has been contaminated from the combustion gas blow by, and will always smell burnt.

Heating and cooling explains how water is condensed from the air in the crankcase, FINALLY Dave you've got it, STOP right here, you've almost got it Dave, it comes from nowhere else, except the heat differential exchange between hot and cold. but not where the water ultimately came from. I'm saying it must come past the rings when the engine is running.

Dave

Originally Posted by PatM

Wow what an interesting read.

Dave and Czar excellent discourse. So is the ultimate answer that our cars would do better without a catch can?
Would a car that is always brought up to operating temperature, even though it is DI, really have no need for the CC versus that vehicle that seldom reaches operating temp or does it really make no appreciable difference? Are I being sold snake oil or is this a legitimate use of my money to help my car last longer??

Pat

Originally Posted by selder

Yes there would, the heat dissipation properties of the different metals, especially the Aluminum engine block, cools a lot faster than say the oil, and this difference in heat exchanges, produces internal water vapour!

I'm sure that I am misreading this...you're saying that in a closed system that contains no water it is possible to create water through "the heat dissipation properties of the different metals."
The implications are staggering.

Originally Posted by Gil-galad

Positive Crankcase *Ventillation*

Blow-by gases contain water vapor from (1) the intake air of non-zero humidity; and (2) combustion chamber ignition (H2O is a normal by product of the combustion process).

End of story.

Originally Posted by minirab

My head hurts; my question is, is the BSH the best occ on the market?

Thanks!

Originally Posted by minirab

My head hurts; my question is, is the BSH the best occ on the market?

Thanks!

Originally Posted by selder

The implications are staggering.