Gen 3 Valve Seals - The Definitive Source of Oil Burning?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Pollymath, Sep 28, 2020.

  1. Pollymath

    Pollymath Junior Member

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    I know there are few people on this board who replaced their valve seals in an attempt to cure oil burning issues.

    My 2010 Prius burns oil like nobody's business. Like, a quart every 1000 miles. Maybe more.

    I've seen theories that this might be due to the coked up and carbonized "stuck" piston rings, but before I go blowing $75 on Valvoline Premium Blue Restore, I thought I'd check to see if the valve seals solved other peoples problems with oil burning.
     
  2. Pollymath

    Pollymath Junior Member

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  3. ASRDogman

    ASRDogman Senior Member

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    There has been non update, yet, of the few that have replaced there head gaskets and
    valve guide seal at the same time.
    I guess they have not put enough mileage on it yet.
    I personally believe the seals are the biggest cause from experience with other engines.

    I think we are all waiting to hear an update...
     
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  4. Pollymath

    Pollymath Junior Member

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    Any ability to squirt some sort of seal softner/conditioner directly on the valve seals, let it sit, and see if the oil consumption decreases afterwards? Even if it doesn't fix cracked/broken seals, it might be enough to identify the problem.

    Somewhere I noticed someone mentioned the relationship between the OCC and PCV. Like, if you OCC wasn't filling up, then maybe you had a PCV issue or vice versa. My OCC is very slow to fill up, despite burning 1qt every 800-1000 miles.
     
  5. ASRDogman

    ASRDogman Senior Member

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    Oil get sucked into the cylinder then burned.
    The seals get hard and brittle. Once they get hard, you can't soften them up.
    You just have to replace them.
     
  6. Pollymath

    Pollymath Junior Member

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    I know how valve seals works and why their failure burns oil.

    To be fair, that's the entire point of seal swell in high mileage oils.

    And, personally, I have seen results from products that claim to make seals more malleable, even once they've been dried and hardened. It doesn't restore them to new, but it does do something.

    Again, the point is merely to use it as a quick and easy determination. I don't want to replace the seals only to find them in excellent shape. It's a PITA process. Then again, by the time I squirt some wonder-lube on them, I'm half way to replacing them.


    I'm still curious if there is a relationship between OCC levels and PCV valve condition.
     
  7. ASRDogman

    ASRDogman Senior Member

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    I have water front property in south Florida really cheap if you're interested.....

    You are free to try whatever you want.
     
  8. Rebound

    Rebound Senior Member

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    The valves and the heads are machined to perfect tolerance to seal. It’s not about being soft or hard; it’s not some kind of gasket or soft material.

    MAYBE you can have some cooked-on deposits which prevent perfect seal. But considering the temperatures and pressure that cooks that stuff on, no magic oil is going to get rid of it.
     
  9. Pollymath

    Pollymath Junior Member

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    No I meant a top end oil of some sort. Essentially getting some sort of conditioner on the top side of the valves and letting it sit.

    Either way, seems like by the time Im that far into it I might as well go all the way.

    I’ll try thicker high-mileage oil, first.
     
  10. mikey_t

    mikey_t Active Member

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    Have you tried the BP treatment of 44K, EPR, and and MOA? They helped alleviate some of my 2010's oil burning after the first run, and I use the EPR/MOA with every oil change now, the 44K once a year.
     
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  11. Raytheeagle

    Raytheeagle Senior Member

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    Good to hear it is still working :).

    How many miles you up to now:whistle:?
     
  12. PriusTheGreenest

    PriusTheGreenest New Member

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    I'm in the market for a Gen 3 Prius. It appears the Gen 3 years 2010-2011 are the worst impacted years for poor seals/blown head gasket issue.

    Although it sounds like Gen 3 years 2012-2015 have less of this issue occurring, can anyone confirm if this issue was completely resolved for Gen 3 years 2012-2015 or just occurs less frequently?
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    I doubt there's much difference. Sometime thru model year 2014 the pistons and rings were revised; that's all I've heard/gleaned. Oh, and EGR valve, and intake manifold had revs, at some point, but don't see that changing oil consumption.
     
  14. mikey_t

    mikey_t Active Member

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    I haven't driven much at all this year b/c of Covid, but I'm around 162k miles. I might switch over to 5W-30 oil at my next change though, as last time I checked it seemed like the burning was picking up again.
     
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