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Air blowing from oil cap

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by MeGuinness, Jan 9, 2017.

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  1. MeGuinness

    MeGuinness Member

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    Ok guys trying to pinpoint a blowby coming out from the oilcap,is effecting mpgs bigtime , down to 37mpg for a couple of weeks untill I realise about the air pressure coming out from the cap and started driving with cap most of it unscrewed and the deepstick half way out, suddenly going up to 57mpgs and car driving much smoother.
    I pull out and cleaned the pcv valve but problem still there .
    Egr pipe ,intake manifold , throttle body ,air tubes all cleaned.
    Ideas and suggestions to pinpoint the problem welcomed please .
    Is there a way to check the valve while is fitted on the car ??? What else to looking for?
    Sticky pistons rings at 190k?
    Thanx

    Posted via the PriusChat mobile app.
     
    #1 MeGuinness, Jan 9, 2017
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    With Hondas they say with engine running, pinch the hose leading to valve, and listen for (faint) click sound. I did this on our son's Civic, heard it, but then we put in a new one anyway, just to be sure.

    My suspicion is that accursed EGR cooler, but am afraid to mention it. I think if it's completely clogged it will cause a warning and code? And not sure if it would causing your symptoms.

    I''ve attached Toyota's PCV valve inspection instruction, a little belatedly. Nothing much to it though.
     

    Attached Files:

    #2 Mendel Leisk, Jan 9, 2017
  3. Former Member 68813

    Former Member 68813 Senior Member

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    Interesting problem we don't hear often in modern cars. If real, points to ring problems and need to rebuild. Is there an oil consumption? Maybe time to do compression check?
     
    #3 Former Member 68813, Jan 11, 2017
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  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I'm wondering whether the catalytic converter might be blocked. I agree though, that the first step should be to check cylinder compression to see how worn out the engine is.
     
    #4 Patrick Wong, Jan 12, 2017
  5. MeGuinness

    MeGuinness Member

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    I checked 2 more friends Prius's....They all blowing from the oilcap and they have only 40k on the clock

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    #5 MeGuinness, Jan 12, 2017
  6. Sam Spade

    Sam Spade Senior Member

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    Yes, there is supposed to be positive pressure in the crankcase.
    Positive Crankcase Ventillation.

    It is highly doubtful that has any bearing on your wide variation in gas mileage.
    I suggest that you need to repeat the "test".
     
    #6 Sam Spade, Jan 12, 2017
  7. MeGuinness

    MeGuinness Member

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    What sensor can be badly effected by the outside temperature??? What I think I see that if weather temperatures are over 11 Celsius car drive ok and no errors showing,as soon the temperature goes down to less then 6 Celsius the engine starts to run rough and I start to get the check hybrid system warning and the engine water pump error too???
    I have the techstream software and waiting for the cable to arrive by post!

    Posted via the PriusChat mobile app.
     
    #7 MeGuinness, Jan 12, 2017
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Try replacing the PCV, as opposed to just the cleaning you did. I know, big $'s and might be all for nought. Just a thought.
     
    #8 Mendel Leisk, Jan 12, 2017
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  9. Former Member 68813

    Former Member 68813 Senior Member

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    maybe you're confusion pulsations with blowback?
     
    #9 Former Member 68813, Jan 12, 2017
  10. Sam Spade

    Sam Spade Senior Member

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    Having ALL of the available information about the failure(s) can get you MUCH better answers.

    The coolant temp. sensor comes to mind.
    But also does the 12 V battery and it's connections.

    How old is your 12 V battery ??
     
    #10 Sam Spade, Jan 12, 2017
  11. MeGuinness

    MeGuinness Member

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    12v replaced 2 weeks ago,was my first attempt to pinpoint the problem

    Posted via the PriusChat mobile app.
     
    #11 MeGuinness, Jan 12, 2017
  12. Sam Spade

    Sam Spade Senior Member

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    That should eliminate that then.
    Did you fully charge the new one before installing ?
    And then did you check the charging voltage when "running" ??
     
    #12 Sam Spade, Jan 13, 2017
  13. MeGuinness

    MeGuinness Member

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    Yes fully..
    battery at terminals and jump posts is over 12.5v
    On the self diagnostic shows 11.5v

    Posted via the PriusChat mobile app.
     
    #13 MeGuinness, Jan 13, 2017
    Last edited: Jan 13, 2017
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Was that 12.5 volts right after charging? In that condition you should see high 12's, or even 13 something. It's called surface charge? 12.5 is what you'd see with a decent condition battery, after some use, when it's sat for without use for a day or two. There are inexorable "phantom charges", constantly chewing away at the battery. Not a lot, and if you're driving daily it's ok.
     
    #14 Mendel Leisk, Jan 13, 2017
  15. MeGuinness

    MeGuinness Member

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    12.5v first thing in the morning from jump points after two days of use from fitted! Taking consideration that was 0celcius outside ... a bit chilly

    Posted via the PriusChat mobile app.
     
    #15 MeGuinness, Jan 13, 2017
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  16. Sam Spade

    Sam Spade Senior Member

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    Neither of those numbers indicates a fully charged battery.
    And if the car was running (ON mode) then those numbers indicate that the charging system is not working.
     
    #16 Sam Spade, Jan 14, 2017
  17. Mendel Leisk

    Mendel Leisk Senior Member

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    What kind of battery is it?
     
    #17 Mendel Leisk, Jan 14, 2017
  18. MeGuinness

    MeGuinness Member

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    Those are with everything OFF.
    The 12v battery isn't the problem in here for sure!
    When in READY mode it shows 14.1v

    Posted via the PriusChat mobile app.
     
    #18 MeGuinness, Jan 14, 2017
  19. MeGuinness

    MeGuinness Member

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    #19 MeGuinness, Jan 14, 2017
  20. Mendel Leisk

    Mendel Leisk Senior Member

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    Looks dimensionally identical, a bit more CCA. Good price too.
     
    #20 Mendel Leisk, Jan 14, 2017
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