PCV Valve replacement: why not removing the inverter coolant reservoir?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Omar Haddad, Sep 5, 2022.

  1. Omar Haddad

    Omar Haddad Junior Member

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    Hi all,

    I am about to replace my spark plugs and pcv valve and clean the MAF sensor and throttle body. I have watched a number of videos and read threads on how to do this, so I have one question. It seems it is always very difficult and uncomfortable to access the valve, as there's no room to maneuver. So, aside from the relay box and air filter assembly, wouldn't it make sense to also remove the inverter coolant reservoir, just to get it out of the way, get more room around the PCV valve, and get it out more easily? It would even allow for fitting a torque wrench in there to give the new valve a specified tightness. Why is nobody doing this? Thanks.
     
  2. JC91006

    JC91006 Senior Member

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    Don't waste your time with the PCV valve, they don't ever go bad on the 2nd gen Prius
     
  3. Mendel Leisk

    Mendel Leisk Underfoot

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    It's right up on top of the valve cover; is access that crowded? One thing: take the hose off it first, and use a closed-ended wrench or socket wrench to remove. Using an open-ended wrench you may put a hole in the valve cover casting when it breaks loose. If you do use such a wrench (to make it easier remove the hose or whatever) be very cautious, and/or lay a strip of steel gauge plate over that zone of the valve cover.

    Repair Manual info attached.
     

    Attached Files:

    #3 Mendel Leisk, Sep 6, 2022
    Last edited: Sep 6, 2022
  4. ChapmanF

    ChapmanF Senior Member

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    [​IMG]
     
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  5. Mendel Leisk

    Mendel Leisk Underfoot

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    Thanks Chap. I wouldn’t know where to find that sketch. :unsure:
     
  6. Omar Haddad

    Omar Haddad Junior Member

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    I am at 185K Miles and the engine is consuming oil. I need to find oit why.
     
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  7. Omar Haddad

    Omar Haddad Junior Member

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    Yes it is. It doesn't look like I would be able to fit a socket and a wrench in there, at all. That's why I am thinking it would be great to try to get that coolant reservoir out of the way. It is attached to the inverter by three 10mm screws. It doesn't seem hard to take it out, but none of the people whose videos I've watched does that. So that's why I'm asking next, is there something wrong with removing it momentarily to get it out of the way while replacing the valve? For instance, would the coolant fluid come out, or would it need to be drained first for some reason?

    Thanks. I will try to follow these tips to the best of my ability too.
     
  8. ChapmanF

    ChapmanF Senior Member

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    I generally do some search like this and scroll until I spot that image or another one you did with dimension lines added to a photo of a wrench, which is in the same thread.
     
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  9. JC91006

    JC91006 Senior Member

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    Getting to the PCV valve and replacing it isn't going to give you the "why" (on the 2nd gen Prius). It'll just give you some exercise in getting to a difficult part that doesn't need replacement.
     
  10. Omar Haddad

    Omar Haddad Junior Member

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    I read in a couple of places that a broken PCV valve may be a common cause of oil consumption. Why do you say that on 2nd Gen Priuses this doesn't apply? The other thing is that I do have to replace my spark plugs (I got a check engine light and the OBD returned the error P0300, random misfiring in the cylinders), and since the access to both is similar, I thought I would replace the valve too, to check on the oil, as well as doing some cleaning while at it.
     
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  11. Mendel Leisk

    Mendel Leisk Underfoot

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    PCV valve is cheap to replace (under $10 USD), and I believe new ones come with thread sealant applied. Cheap experiment anyway.
     
    #11 Mendel Leisk, Sep 6, 2022
    Last edited: Sep 6, 2022
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  12. JC91006

    JC91006 Senior Member

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    The reason I tell you this is because I've removed at least 10 of these in my years of owning multiple Gen2 cars, not once have I found a bad PCV, they all rattle and did their job. And I've talked to many Prius mechanics that have the same experience with the Gen2 cars.

    But as mentioned above, there is no harm in changing it, go for it and have fun.
     
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  13. pasadena_commut

    pasadena_commut Active Member

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    The PCV valve on the gen 2 is in about the most inconvenient place imaginable while still being "near the top of the motor". Conversely, the other end of the tube attached to the PCV is very accessible. I wonder why they didn't put the PCV valve on the accessible end of the tube? My best guess is that in that configuration the tube would gunk up with oil before it reached the PCV. Either that or they just didn't care how hard it would be to service the PCV.

    For the OP, I believe the consensus for "why these cars burn oil" is that the rings get stuck, usually because oil changes have not been frequent enough. Fixing this sort of problem with additives and such is a black art of dubious value. It wouldn't hurt to change the oil a little more frequently, to see if constant exposure to pristine oil can dissolve some of the gunk and release the rings. It probably won't help though.

    If it is the rings the real fix is a ring job. Lot of work if you do it yourself, or a lot of money to have somebody else do it, your choice. Unless it is burning a quart every tank it is usually cost effective to keep adding oil.
     
  14. Omar Haddad

    Omar Haddad Junior Member

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    Sure, here are some images.

    This is my car, as it is with nothing removed. The yellow plastic container (the coolant reservoir) is attached to the big gray inverter on the right side:

    20220906_185214.jpg


    Next, in this screenshot, a youtube user is replacing the PCV valve. He has removed the relay box, the air filter, and the hose cover to expose it. He also detached the hose from the valve. But he hasn't removed the coolant reservoir. There is very little room there, and he is using an open ended wrench, leveraging it with a second wrench hooked on the other end. As you can see, you could not fit a socket wrench in there:

    Screenshot_20220906-190419.png


    Finally, this third photo shows the same area but the coolant reservoir has now been removed. This screenshot is from a video where the reservoir itself is being replaced, so the youtube user completely drained the fluid first:

    Screenshot_20220906-185710.png


    My question is, can the coolant reservoir be removed to replace the valve comfortably but without draining the fluid? I am just wondering why, with so many videos on how to replace the valve, everyone complains that there's so little room there but no one removes the inverter coolant reservoir. Is there a reason no one does this?

    Thank you.
     
  15. Omar Haddad

    Omar Haddad Junior Member

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    Thank you. I've had the car for four years and I think the former owner might have changed the oil nkt very often. Thank you very much for the information on the rings. I'll definitely look into that.
     
  16. Tanman

    Tanman Junior Member

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    This PCV valve is very simple to change with a ratcheting box end wrench!


    iPhone ?
     
  17. rjparker

    rjparker Tu Humilde Sirviente

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    Piston rings are the most common reason for oil burning followed by valve stem seals. Pcv valves stuck open is sometimes cited as a possibility but is rarely the cause. Since it is cheap go for it. But don't discard the old spark plugs before having an experienced person look at them for signs of oil burning.

    The same experienced mechanic can perform a dry and wet compression test to help isolate the rings or valve seals. Wet means adding a little oil to each cylinder to restore weak compression. Generally that will point to the rings. It is somewhat common to have bad rings and valve seals. The typical "blue smoke" diagnosis does not work on modern cars since the catalytic converter eliminates the blue oil smoke.

    However excessive oil burning over an extended period can ruin the catalytic converter by clogging it up. At that point (rarely seen) the engine runs very poorly. Usually its bad rings causing excessive oil consumption which requires a rebuild to fix. During an engine rebuild the head should also be machined as necessary and new valve seals installed.

    Finally Toyota often suggests it takes a quart every 1200 miles or less to be considered excessive. Obviously good engines burn much less than that.
     
  18. TMR-JWAP

    TMR-JWAP Senior Member

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    I think the coolant reservoir is formed with a plastic tube on the inverter side, that inserts into the inverter and seals with an o-ring. The fasteners keep it locked in place. If you remove the reservoir, it's just like popping a hose off and it will drain. Not 100% sure, but that's what I seem to remember.
     
  19. Omar Haddad

    Omar Haddad Junior Member

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    Interesting, but watching this video,

    it seems that it's just a container. The only tube where the coolant comes out of is where that hose goes in. Who knows. Maybe nobody removes the reservoir because the screws are a pain to get to and nobody cares for torquing the valve properly. I guess I'm just going to try it and see what happens. Thank you. I'll post an update.
     
  20. ChapmanF

    ChapmanF Senior Member

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    TMR is right, the second connection is directly to the inverter, with an O ring.

    If there were only one hose connection, how would the coolant circulating out through that hose be returning to the reservoir?
     
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