Oil Catch Can (aka Air-Oil Separator)?

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Mendel Leisk, Oct 22, 2017.

  1. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Anyone done this on a 4th gen, or thinking about it? Strategies?

    No time like the present.
     
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  2. xliderider

    xliderider Senior Member

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    You should provide a link to the Gen 3 thread, so the Gen 4 ppl will know what the concern is all about. ;)

    Posted via the PriusChat mobile app.
     
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  3. Prodigyplace

    Prodigyplace Senior Member

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    I have only had mine a year and less than 12K miles. I know about them but figure I can wait a while longer. :D
     
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  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Good point. I guess @danlatu 's thread is the main one:

    Oil Catch Can, Eliminate that knock! | PriusChat

    The main culprit seems to be airborne oil mist from the PCV valve, condensing/pooling in the intake manifold, and maybe getting sucked into the combustion chambers as well. This is something that's happening from the get go, maybe you can't be too soon? I've heard more that one comment about adding this right away, with a new vehicle.
     
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  5. Prodigyplace

    Prodigyplace Senior Member

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    You are assuming they made no changes for Gen 4. We know they increased the fuel efficiency of the engine. I believe somebody had suggested that a design change could have alleviated the issue,
     
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  6. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Maybe you're thinking of the EGR improvements? Not sure. A relocation of the PCV valve, positioning higher up on the crankcase wall might help, or a better baffle system leading to the PCV valve connection. Not sure.

    If you can get a look down the throat of the throttle body and see oil beyond, that would be a tip off to the need for an OCC.
     
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  7. Prodigyplace

    Prodigyplace Senior Member

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    How easy is that to get to? I assume it is under the plastic top cover?
    I just have not worked much on a Prius.
     
  8. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Removal of intake manifold is likely the best approach. There's (as far as I know) a couple of hoses, if it's similar to 3rd gen.

    One hose (the one you're maybe thinking of) goes from the valve cover to a spigot on the intake air snorkel, at a point between the air filter and the throttle body.

    The other hose, and this is the trouble maker, runs between the Positive Crankcase Ventilation (PCV) valve (mounted high on the crankcase wall, below intake manifold), to a spigot on the side of the intake manifold, downstream from the throttle body.

    An OCC is typically installed along that second hose.
     
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  9. Prodigyplace

    Prodigyplace Senior Member

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    Pictures? I guess I am more visual.
    On my Tundra, the intake manifold is pointed out the front of the engine. I would just need to remove the air cleaner hose to inspect.
     
    #9 Prodigyplace, Oct 23, 2017
    Last edited: Oct 23, 2017
  10. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Here's the hose between PCV valve and intake manifold on 3rd gen. Throttle body is mounting on Intake Manifold just to the left of left end of hose, PCV valve is screwed into crankcase on right end.

    upload_2017-10-23_10-0-39.png

    I ended up cutting that hose at the mid-point, rotating the two resultant "elbows" downward, and splicing in the oil catch can.

    Best I can do btw, haven't got a 4. You might be able to see the PCV plumbing, by just removing the air intake snorkel and air filter box: the intake manifold looks very compact and high up.
     
    #10 Mendel Leisk, Oct 23, 2017
    Last edited: Oct 23, 2017
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  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    This might be the hose on the 4th gen:

    upload_2017-10-23_10-27-42.png

    If not, it's likely in that mass of spaghetti, somewhere.
     
    #11 Mendel Leisk, Oct 23, 2017
    Last edited: Oct 23, 2017
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  12. Mendel Leisk

    Mendel Leisk Sand Pounder

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  13. RMB

    RMB Senior Member

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    Oh well, this OCC topic isn't very popular with Gen 4 members. Either Gen 4's are still new to cause any concerns and/or the improved systems won't cost problems?
     
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  14. Mendel Leisk

    Mendel Leisk Sand Pounder

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    A bunch of procrastinating grasshoppers, lolling in the summer meadow... :rolleyes:

    Pot calling the kettle black: it took me to 70K kms to wake up, but eight-o'clock-day-one is the optimum time to address this.
     
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  15. Raytheeagle

    Raytheeagle Senior Member

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    How much oil have you caught with your new setup?
     
  16. RMB

    RMB Senior Member

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    I will check on it this coming Saturday, exactly one week after installing my OCC. I didn't drive my Prius Sunday and Tuesday, so probably wasn't enough driving to warrant a measurement, but after a week I will have better picture of how much oil go through the PCV and into the intake manifold.
     
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  17. Mendel Leisk

    Mendel Leisk Sand Pounder

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    I got a scant tablespoon, if that, in the first 350 kms or so. My setup is pretty much only accessible from below, so it'll be spring oil change when I'll open the drain tap again, measure what comes out. I've got a wee jar that I've engraved with CC lines, will see what I get with 4~5K kms.

    More telling, pull the throttle body again (or at least have a look through the throat), and see if it's stayed oil-free. I suspect besides the PCV, a slight amount is trickling down from the intake ports.
     
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  18. RMB

    RMB Senior Member

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    IMG_3617.JPG
    177 miles since installing oil catch can, exactly one week ago. Normal routine driving except for the very same day going home after the meetup where there was a full throttle uphill section on Hwy24, HSD indicator way up in the Power section. Probably blew more oil into the catch can than my normal route would do. From the picture I took, what do you estimate of the collected amount? I think maybe about 5 ml? That estimate is comparing to my baby boy's formula bottle LOL.

    When I installed the catch can, I didn't pull out the intake manifold for a thorough cleaning, but I did see a puddle of oil underneath the throttle body. But then, both sides of the throttle plate was very clean. Today I didn't have time to pull out the air intake box and snorkels to look at the throttle body for comparison, I doubt there will be any difference since there was oil in the manifold before adding the catch can.
     
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  19. Raytheeagle

    Raytheeagle Senior Member

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    The Oakland Hills around the Caldecott tunnel are pretty steep:(.

    When I was going to the Children’s hospital in Oakland a couple of weeks back, I could see the effect on mpg.

    I’m just glad I don’t have that commute everyday:whistle:.

    There are better ways to spend 2.5 hours in a morning (y).
     
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  20. Prodigyplace

    Prodigyplace Senior Member

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