PCV Oil trap

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gary brings up a good point, about the c. can being maintenance free. i have the standard type setup, with the incoming and outgoing hoses on top, but with nylon fittings. i unscrew the plastic bottle from the top, and empty it.as i don't drive much, the bottle only "fills" about 1/2" every couple of weeks in the winter. there is that off white moisture laden crud that collects on the side of the bottle, as well. i wipe it clean,and reinstall. it takes about 45 secs. in the summer, i do nothing.
i like this setup because i want to see the garbage that is collecting in the bottle. the original install took about 10 minutes -- a 1 beer job. they're both good setups.
the market is opening -- gotta go.if i don't get back to the site today -- happy new year to all.
 
Originally Posted By: chevrofreak
But, I'm having problems with it breaking due the amount of vacuum, not with the efficiency of the catch can. The amount captured didn't come close to equaling the amount of oil that my engine is consuming otherwise, so it didn't seem worthwhile to try to build something that would withstand the pressure. I would also have no way of mounting it high enough to return the fluid to the sump, and I'm not sure I want that stuff going back into my oil anyway. It's an old car, with over 140,000 miles on it. I'm not too worried about getting more life out of it.


The PCV valve is a regulated and filtered manifold leak. I'd imagine it would take either a decent length of hose down stream of the can to provide enough restriction to collapse the thing ..or maybe if the chamber itself had a small inlet ..but
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If the junk is moisture, it already most likely lining your interior valve cover anyway. That is, unless it's some localized cold spot due to air flow and some aluminum material ..the moisture was already a vapor (like relative humidity) and would have no condensing medium to shrink it down to water. It's in the air. The heavier oil vapors will just drop out.

..but I'm not necessarily saying that this is for you in your circumstance. I'm merely expanding the discussion for those who may not have considered other options. It's typically not hard to install one ..nor empty it, there are just other options to make them a passive and self maintaining device.


While I'm constantly scheming on some better mousetrap ..that mouse trap will have its core DNA wrapped around "SET IT AND FORGET IT!"
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Originally Posted By: Gary Allan
Originally Posted By: chevrofreak
But, I'm having problems with it breaking due the amount of vacuum, not with the efficiency of the catch can. The amount captured didn't come close to equaling the amount of oil that my engine is consuming otherwise, so it didn't seem worthwhile to try to build something that would withstand the pressure. I would also have no way of mounting it high enough to return the fluid to the sump, and I'm not sure I want that stuff going back into my oil anyway. It's an old car, with over 140,000 miles on it. I'm not too worried about getting more life out of it.


The PCV valve is a regulated and filtered manifold leak. I'd imagine it would take either a decent length of hose down stream of the can to provide enough restriction to collapse the thing ..or maybe if the chamber itself had a small inlet ..but
21.gif


If the junk is moisture, it already most likely lining your interior valve cover anyway. That is, unless it's some localized cold spot due to air flow and some aluminum material ..the moisture was already a vapor (like relative humidity) and would have no condensing medium to shrink it down to water. It's in the air. The heavier oil vapors will just drop out.

..but I'm not necessarily saying that this is for you in your circumstance. I'm merely expanding the discussion for those who may not have considered other options. It's typically not hard to install one ..nor empty it, there are just other options to make them a passive and self maintaining device.


While I'm constantly scheming on some better mousetrap ..that mouse trap will have its core DNA wrapped around "SET IT AND FORGET IT!"
55.gif


What could be done is just put a straight fitting in the valve cover hole and put the PCV valve after the can. The highest vacuum should then be after the PCV.
 
Originally Posted By: Onmo'Eegusee

What could be done is just put a straight fitting in the valve cover hole and put the PCV valve after the can. The highest vacuum should then be after the PCV.


Yes, that would work too. On my son's NEON I have a long hose that the PCV valve plugs into. It take the long trip before ever seeing the valve. The vertical lift is just too far/high for the stuff to stay an integrated flow.
 
Hmmn this thread has my gears whirling. My 528es have no PCV valve.Just a hose from the valve cover to the throttle body My first one used a quart of oil every 1500 miles due to an external headgasket leak. It also would foul the air filter with oil after a year or so. Could some body please 'splain to me how oil condensate flows against intake through the throttle body, through the AFM into the airbox? The AFM is pretty level.
My present 528es have much less miles,they use less oil but still oil reaches the airfilter over time.
The vent hose hose is about 18" and is maybe 5/8 in diameter. I guess I should rig a catch can, but a closed system is closer to what BMW uses.
 
Originally Posted By: andyd
Hmmn this thread has my gears whirling. My 528es have no PCV valve.Just a hose from the valve cover to the throttle body


That sounds like a CCV system- where there's just a fixed small orifice like a carburetor jet (bad analogy- nobody remembers those anymore!) in-line between the valve cover and the intake manifold. Jeep 4.0s are one of the most common applications of that system. Its less "aggressive" at scavenging blow-by out of the crankcase than a PCV system, and so it rarely contributes much to oil consumption. The flow is too slow over most of the system to entrain oil mist.

Originally Posted By: andyd
Could some body please 'splain to me how oil condensate flows against intake through the throttle body, through the AFM into the airbox?


It doesn't. You must have a second hose from the crankcase to the air-box, all systems do. Under normal conditions, air flows *into* the engine thru that hose, but at wide-open throttle the CCV/PCV system doesn't have any vacuum to work with, so blow-by from the engine goes back out that hose to the airbox. THAT is what soils the air filter with oil, and if it does it really badly then its a sure sign that a) the CCV/PCV system is not working, or b) the engine rings are shot and blow-by is excessive.
 
440, there is no second hose to the air box. Just the one from the VC to the throttle body. I do my own service and have the air box and AFM, off the engine all the time. It is an easy job and removing gives access to the left side of the engine.
 
Odd- there's GOT to be some source for fresh air to enter the crankcase to displace all the blow-by that the PCV or CCV removes. Otherwise its just a sealed system and would be prone to sludge and oil breakdown from all the crud that gets retained in there.
 
440 - You've got to be kidding! You did that to your own car??

You absolutely DON'T want to drain back any PCV residue into the engine! This is worse than no PCV at all!
The residue is not oil, but only a very little amount of oil, with condensed blow-by gasses, acids, water vapor, etc..
Pure doo-doo.

And that filter is restricting flow, on top of it all.


A truly terrible set up!
Please don't anybody copy this!
 
Horse hookey, mechtech2
lol.gif
Lots of engines use the same system in other configurations. Go look at a 3 series 6 cylinder. Full manifold vacuum and a 2" vent to the intake. No velocity at all. Just pure volatilized vapor. It never leaves unless it's smoke or "dry water".

Let the oil take care of whatever it is instead of fouling the intake tract or the combustion chambers or the catalyst (for those who worry about their cat). You change the oil ..and most do it way too early for the ever highly coveted "peace of mind" quotient.
 
Originally Posted By: mechtech2
440 - You've got to be kidding! You did that to your own car??

You absolutely DON'T want to drain back any PCV residue into the engine! This is worse than no PCV at all!
The residue is not oil, but only a very little amount of oil, with condensed blow-by gasses, acids, water vapor, etc..
Pure doo-doo.

And that filter is restricting flow, on top of it all.


A truly terrible set up!
Please don't anybody copy this!


Many cars have PCV/oil separators from the factory that drain right back to the crankcase.
 
For around 15 dollars last time I checked, is the OE separator used by BMW and Porsche. Line to the intake, air filter box in some applications, and sump for oil drain.

931_oil_separator2.jpg
 
Last edited:
Originally Posted By: andyd
Hmmn this thread has my gears whirling. My 528es have no PCV valve.Just a hose from the valve cover to the throttle body My first one used a quart of oil every 1500 miles due to an external headgasket leak. It also would foul the air filter with oil after a year or so. Could some body please 'splain to me how oil condensate flows against intake through the throttle body, through the AFM into the airbox? The AFM is pretty level.


I've got an E30 323i with a cotton air filter.

Oil literally drips out of the air filter
 
Originally Posted By: mechtech2
440 - You've got to be kidding! You did that to your own car??

You absolutely DON'T want to drain back any PCV residue into the engine! This is worse than no PCV at all!
The residue is not oil, but only a very little amount of oil, with condensed blow-by gasses, acids, water vapor, etc..
Pure doo-doo.

And that filter is restricting flow, on top of it all.


A truly terrible set up!
Please don't anybody copy this!


Dude, its JANUARY first, not APRIL first.
grin2.gif


PCV traps are a common factory solution. The "Doo doo" to which you refer (combustion byproducts- moisture, hydrocarbons, etc.) is in VAPOR form and goes right through to be disposed of. Good clean oil mist gets trapped and saved.
 
Originally Posted By: yeti
gary --your post looks like a rorschach test.


Which one didn't look like a butterfly?? (
56.gif
)
 
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