Point of oil catch can?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by kehyler, May 1, 2019.

  1. kehyler

    kehyler Junior Member

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    Can someone explain the utility of an oil catch can for me? After taking off my air intake, there was some oil in the bottom of the manifold, but it would have to travel against gravity for like 8 inches to make it up to the actual intake into the cylinders. Becuase of that travel against gravity, I'm unsure what, if any, marginal utility an oil catch can offers.

    Thanks!
     
  2. spiralhelix

    spiralhelix Active Member

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    Let’s see if I get this right since I’m new to the OCC idea.

    There seems to be an unusually high amount of oil making it past the PCV (valve) which empties into the intake manifold. Since the intake manifold how has oil pooling in it, warm exhaust gas from the egr is now pulling small amounts of oil into the intake chamber, past the fuel injectors, through the intake valves and into the combustion chamber. Small oil particulates then exit the exhaust manifold and make their way to the EGR cooler which then cools the oil on the fins. Cooling the oil makes it sticky and the cooler fins start clogging (like arteriosclerosis). Once the clogging is so thick that exhaust gas no longer passes through the egr system and back into the intake, the engine then has to get cooler air which then burns hotter, causing the head to expand at a different time than the block. The friction caused by the differing expansions leads to excessive wear on the head gasket and eventual failure.

    Sooooo an OCC keeps oil out of the intake and egr so the exhaust gas is not contaminated with excessive oil particulates.
    People that are installing them are reporting cleaner intakes and EGR

    At least this is how I have perceived their use from reading on it over the last month.


    -Spiral
     
  3. spiralhelix

    spiralhelix Active Member

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    I should mention that the pcv output is near the top of the intake manifold, so oil is actually passing by the intake ports on its way down to the throttle body.


    -Spiral
     
  4. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    The PCV hose feeds air from the crankcase into the intake manifold. That air has oil/water/gas mist in it. Some condenses, forms a pool at the bottom of the intake manifold, but very likely most does not condense, flows on through as a mist, into the combustion chambers.

    Just emptied my Oil Catch Can, with a spring oil change: the collected gunk since last fall was about 100 cc. Once it settles, some oil at the top, but mostly brownish cream colored goop. At the fall oil change, it'll a lot less, and mostly oil, maybe 30 cc at most.

    There's a couple of PCV hoses. One at the top between the valve cover and the snorkel heading to the throttle body. The other, the main one, comes from the PCV valve and connects to the intake manifold down pretty much at the bottom, on the right side (standing at front of engine) and below the throttle body.
     
    #4 Mendel Leisk, May 1, 2019
    Last edited: May 1, 2019
  5. Grit

    Grit Senior Member

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    The combustion product, or blow by, recirculates back into the crankcase. With the can, blow by goes into the can before returning into the crankcase. And your right, the pool of oil won't even make it way to the can. But a good amount of blow by will.
     
  6. orenji

    orenji Senior Member

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    This is what I had after only several thousand miles. The throttle body was spotless. OCC works! D6324A66-3F80-42B4-B2ED-459EF5EB81BD.jpeg
     
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  7. kehyler

    kehyler Junior Member

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    If the concern is oil in a mist form that can continue against gravity, what in oil catch cans stops this mist?
     
  8. spiralhelix

    spiralhelix Active Member

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    The filter in the can.


    -Spiral
     
  9. kehyler

    kehyler Junior Member

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    Gotcha. I wonder if the oil catch can increases the crankcase pressure some, and whether or not this could cause any issues.
     
  10. Grit

    Grit Senior Member

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    The oil catch can thread that has over 270 pages will answer your question, its not confusing either.
     
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  11. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    A labyrinth of some sort. It's more like a (moonshine) still than a filter: you run the mist-laden air through convoluted passages with surface area, with the object of condensing/trapping that mist. There's various methods to accomplish this. Even an open can will do this to some degree, but a labyrinth helps.

    And then some will have a filter at the outlet as well. Maybe that's prone to clog though. Or you could add an inline filter, just past the can, I think some have done that. You'd want to monitor the condition of the filter though; you don't want to obstruct the PCV flow.

    Here's some pics of my Moroso 85474 can. I'd taken it off to see how it looked inside, and changed the hose clamps to more kosher automotive style.

    It has symmetrical chambers. The air comes in, on either side, doesn't matter which you make inlet or outlet, with this design. Each chamber has a stainless steel "wheatie" that the air has to get through. The mist tends to condense on the mesh, drip down into the bottom chamber, which has a spigot and tap. This style is good for bottom mounted, if you're ok with draining it in conjunction with oil changes, for example.

    upload_2019-5-2_7-27-10.png
    Inlet is on the right side, air comes in, works it way through the right side wheatie, then through the holes in the bottom plate, around and up through the left side wheatie, to exit. You can see the right side of the plate is more grungy, oil/sludge dripping down from that side:
    upload_2019-5-2_7-28-28.png
    upload_2019-5-2_7-29-0.png
    Chambers:
    upload_2019-5-2_7-29-32.png
    Stainless steel "wheaties":
    upload_2019-5-2_7-30-0.png
    Bottom half, already drained, but some still some dregs:
    upload_2019-5-2_7-30-47.png
    An overall picture:
    upload_2019-5-2_7-35-52.png
     
    #11 Mendel Leisk, May 2, 2019
    Last edited: May 2, 2019
  12. kehyler

    kehyler Junior Member

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    Thanks, I've learned a bit.

    Can someone explain to me how, while cruising on the highway (so hp demand from engine is same), colder intake air leads to higher engine temperatures?
     
  13. Rebound

    Rebound Senior Member

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    It doesn’t. Who says it does?

    Colder intake air is more dense. This lets you get higher horsepower, because you can have more oxygen in the combustion chamber.
     
    #13 Rebound, May 2, 2019
    Last edited: May 2, 2019
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  14. spiralhelix

    spiralhelix Active Member

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    https://www.ias.ac.in/article/fulltext/sadh/029/03/0275-0284

    Read the first two paragraphs of the Results and discussion section. I’m not a mechanical engineer to know the finer points. I also get that research was specific to Diesel engines. But it seems like one of those things that if it is important enough to have included in the system, create a TSB about it, and have plenty of people experiencing the same symptoms and failures, it plays a key role.

    I don’t think we are talking about a difference of 10°. But small changes may have big effects. Think about torque specs. To little and the thing could come apart. Too much and the bolt could break.
     
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  15. kehyler

    kehyler Junior Member

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    You liked Sprial's post. I don't think that colder intake air leads burning hotter, perhaps unless you are flooring it.
     
  16. Grit

    Grit Senior Member

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    Prius is smart enough to adjust and balance engine to provide the same output under various air temp and amount of air from intake. The obvious higher temp on highway is prius pushing through air molecules, gravity & etc.

    Look up might car mods on youtube for a video on cold air in take on a dyno. They force fed actual freezing air into a car air intake and dyno tested before and after results, virtually no power difference.
     
  17. kehyler

    kehyler Junior Member

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    I'm not seeing how this answers my question. Let's say you have two prius' driving under identical conditions. The only difference is a difference in the temperature of the air in the intake manifold, which can we infer anything about the temperature in the combustion chambers?

    I agree with that, which leads me to think that the answer to the above question is no, we should not expect a difference in the combustion chambers. However, this disagrees with what other members have expressed in this thread, so I'm curious who is right.
     
  18. Raytheeagle

    Raytheeagle Senior Member

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    The engine temp is moderated by the engine coolant loop thanks to the thermostat there to control it:).

    What the oil catch can does is ensures that light components do not migrate to a space that will allow for incompressible fluids to try and be compressed. That doesn’t end well;).

    Cleaning the egr circuit ensures that the returning air from the exhaust system can be evenly divided amongst the 4 cylinders. If one is clogged, now there is imbalance and leads to issues you read about here:cool:.
     
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  19. Rebound

    Rebound Senior Member

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    I don’t think there’s anything relevant in those two paragraphs:
    “At fixed power conditions, as the percentage EGR increases (0–21%), the temperature of the exhaust gas continuously decreases. This is shown in figure 4.
    Earlier it was mentioned that the most important reason for the formation of NOx in the combustion chamber is extremely high temperature. Our experimental results indicate (figure 4) a decrease in the exhaust temperatures with increasing EGR, therefore it can be safely concluded that the combustion chamber temperatures also decrease and thus the formation of NOx is decreased.”

    What’s confusing?
    Using EGR reduces tailpipe emissions. That’s why it’s done. You’re asking why hotter gas creates higher horsepower, and this study doesn’t say that hotter combustion increases power, it says that hot combustion increases emissions.
     
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  20. kehyler

    kehyler Junior Member

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    Does anyone know of an CARB certified oil catch can?
     
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