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P0300, 0301, 0302, etc.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by AlexS, Mar 19, 2022.

  1. AlexS

    AlexS New Member

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    Hi all! New to the forum, but desperate for help. I’ve been trying to research all I can and fix this as quickly as possible in order to get my vehicle back on the road. For starters, I have a Gen3 2013 Prius with ~198k miles.

    More recently, I noticed knocking on startups only and had some misfires. I replaced spark plugs and ignition coils - everything worked for rough a week, until similar inconsistent issues arose with misfires. I cleaned the fuel injectors (they were very dirty) and tried cleaning one of the EGR pipe components (part that connects EGR to air intake manifold). I am still getting this inconsistent misfire (and it happens on different cylinders - for a while it was only cylinders 1-2, then just cylinder 1, now cylinder 3 is involved).

    Should I assume this is a head gasket? I didn’t start monitoring coolant until very recently, but since refilling I’ve noticed very little gone (and it’s been driven a couple hundred miles). I want to assume it’s a head gasket and just replace, but used the engine block test (BT-500) to test if there were combustion fumes and so far have yielded no yellow color after two attempts (one of which I had the Prius run for roughly an hour).

    Your help and expertise is much appreciate here! The thing that’s weird to me is the multiple different cylinders misfiring at different times. My fuel economy has remained normal through all of this. Any next steps / advice would be much appreciated! Trying to fix this as it has caused my wife and I a bit of stress and I plan to fix myself (whatever the issue) to save money. One final note - I am local to Kansas City. Open to all recommendations! Thanks all.
     
  2. AlexS

    AlexS New Member

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    One other note - I had oil changed and no comments were made on oil. I’ve driven and had no indications that coolant was mixing with my oil based on dipstick and engine.
     
  3. AlexS

    AlexS New Member

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    Last note - this is an inconsistent issue. It doesn’t happen every start or even every cold start. Sometimes it sounds worse than others and will do it a few times in a row other times it works well.
     
  4. bisco

    bisco cookie crumbler

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    welcome!
    i would clean the entire egr circuit, then replace the injectors if that doesn't help. or you could try running some injector cleaner, i think there are threads here.
     
  5. abdullah arslan

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    firstly, you ve all the answers and solutions in this forum.
    Other than pipe and injectors, which were very dirty, that refers intake's clogged, the car struggles breath in, as well as breathing out, EGR.
    My understanding is that I'd clean intake, check coils & plugs (clean or replace). While Intake out,change PCV valve and intake gasket and install oil catch can. After this, things should be smoother, then next step is cleaning EGR unit, which is thougher than first.
    And I'd do an early oil change to keep it in control. Videos available in this forum how to do those, if you can change oil yourself, you are qualified to do all.
    After all done, if still leaking coolant, may do leak-down test

    Posted via the PriusChat mobile app.
     
  6. Tombukt2

    Tombukt2 Senior Member

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    If you are in fact chasing a blown head gasket coils cleaning and all the like I'll probably going to make a little or no difference and coils and how many sets are you going to buy the issue was on the refill of the coolant when you noticed it was down how much was gone before you refilled it we don't care about after that was the first indicator it gulped some coolant
     
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    You should do a full EGR cleaning, but: that isn’t go to turn back the clock. It’s best done about 98k sooner.

    Leak down test and/or boroscope inspection will see where you’re at with head gasket.

    first link in my signature has EGR cleaning info.
     
  8. AlexS

    AlexS New Member

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    Thanks everyone - will follow suggestions and keep you posted.

    thank you for all of the suggestions!
     
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  9. AlexS

    AlexS New Member

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    @Tombukt2 i refilled it a couple of weeks ago after noticing it was very low. I hadn’t filled coolant in who knows how many miles (I’m embarrassed to admit). I thought this may have been something I overlooked in the past, but was unsure so have been monitoring ever sense.
     
  10. bisco

    bisco cookie crumbler

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    i have never touched mine, and it is at the correct level
     
  11. AlexS

    AlexS New Member

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    Alright update.

    After a rough misfire today twice I tested the car without the EGR component (followed a YouTube video with a suggestion of cutting off the circulation from the EGR pipe). What I learned:

    Still had severe knocking. Coolant was noticeably lower now with white smoke coming out of the tailpipe. Smelled sweet like coolant.

    I’m going to go ahead with assuming this is a head gasket issue and follow the gasket masters video. Only concerns:

    Do I need to get my engine block remachined to be level? Or can I just throw this gasket on there. I do not have a personal shop capable of doing this is why I ask.

    Do y’all have any suggestions on other issues to look for while I’ve got everything off? Is there an easy way to identify other messed up components like bent pistons, etc.?

    And my final question - do you all recommend replacing the PCV valve while I’m at it along with a new timing chain tensioner / gasket? I know GasketMasters mentions the timing chain tensioner.
     
  12. DItd

    DItd New Member

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    I am no expert but newbie with similar symptoms. At 218k on a 2010 with start up knocks I cleaned egr and intake manifold with Purple Power found at Tractor Supply (PP not good on aluminum or rubber gaskets). Replaced plugs and PCV (why not it costs so little). Helped but did not solve the problem. Leak down test, coolant drop and continued knocking has convinced me that I have a slow coolant leak between Cyl #1 and #2. I am gathering supplies and tools to replace HG. I have spent weekend watching hours of HG replacement videos.
    I have not seen anyone recommend replacing timing chain tensioner. The timing chain tensioner gasket yes but not the tensioner itself. Do you have link to GasketMasters instructional videos? I have spent hours watching his Baltimore unedited video. Helpful but a lot of time spent to pick up tips. Best resources I have found to date are PriusChat, videos made by GasketMasters, Riviera Auto, SaneAuto, Lets Drift Media.
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    The "cylinder head" link in my signature has some Repair Manual excerpts, one of which I believe has the head trueness specification if I'm not mistaken. I'll take a look, try to be more specific.

    One thing: YouTuber "The Car Care Nut", a Toyota master mechanic, cautions against machining the head (or block), saying it can change the distance between crank and cam shafts sufficiently to throw the timing off. Not sure if he's a bit of an alarmist, not really sure. Depends on the machining technique and amount shaved off??

    Addendum: Repair Manual is saying if it's out of spec, to replace, fwiw:

    upload_2022-3-21_6-38-42.png
     
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  14. AlexS

    AlexS New Member

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    Thank you I'll definitely look into this. I have not overheated yet (to my knowledge either), but also wanted your opinion. When you've done your gasket replacements, have you had any issues with cracked cylinder heads or bent piston rods? My car still sometimes starts smoothly so I think I could be in the clear.

    Update on overall situation: Gasket sealer and head gasket are both in the mail. I called local auto shops and got quoted ~3500-4000 so far and they mentioned cracked heads, etc..

    Thanks again for the help everyone. Will keep you posted.
     
  15. Mendel Leisk

    Mendel Leisk Senior Member

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    Just speculation: cylinder to block tolerance spec is .05 mm,(aka 1/20th mm). If the measured variation was slightly more than that, say 0.1 mm (aka 1/10th mm), It seems to me if a machine shop could manage to machine off that amount it would not impact timing; it's so infinitesimal. One technique I've seen is they place a large sheet of fine sand paper on a plane surface, invert the head on it, and swirl it around, till all low spots are gone.
     
    #15 Mendel Leisk, Mar 21, 2022
    Last edited: Mar 21, 2022
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    This one's pretty good:



    Never done any of this, lol.
     
  17. Tombukt2

    Tombukt2 Senior Member

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    Dinhad a crack in the crown of no2 the meccie thought it did not go through . It blew out in. 14 miles enroute home w new gasket installed . No due diligence . Partially my fault I should have stopped that job dead in tracks.
     
  18. AlexS

    AlexS New Member

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    Hey all! See attached photos of the cylinders. Any comments on these photos? @Mendel Leisk
     

    Attached Files:

  19. Mendel Leisk

    Mendel Leisk Senior Member

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    Hard to say. They look quite uniform. Which is which?
     
  20. Mr. F

    Mr. F Active Member

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    I did have a bent rod, but I found out only after I'd taken the head off. Replacing it is a little tedious but not too bad. One would need to take off the stiffening crankcase assembly from underneath the vehicle to get to the connecting rod caps. The only extra tools you'll need are a piston ring compressor (free rental from auto parts stores) and a 12-point 10 mm shallow well socket.

    Once the head was off I checked the flatness with a straightedge, and since it was well within spec I didn't bother to get it inspected for cracks—my reasoning being that if it never overheated enough to warp it out of spec, there wouldn't be any cracks.

    By the way, I had smooth starts too, even with that bent rod.
    rod.jpg
     
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