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Considering Head gasket replacement - 2011 Prius - 215k miles - P0303 misfire

Discussion in 'Gen 3 Prius Technical Discussion' started by An2TheTwan, Jul 18, 2022.

  1. ASRDogman

    ASRDogman Senior Member

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    Well, good luck with that.....
    From what other's have said, and what the photo's look like, how are you going to remove the bolts
    behind the clutch assembly without removing it? Which can't be removed while attached to the transmision....
     
  2. Bill Norton

    Bill Norton Senior Member

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    I wonder if there are very high mileage owners that have followed this advice and are happy with the results?

    As for gas,,, The Prius is a variable compression ratio Pseudo-Atkinson engine WITH a knock sensor.
    It should not be effected by octane rating of the gas.
    Which is also why I used to question the theory of keeping the EGR clean.
    Pre-ignition/knocking should not be happening in this engine.
    And even if there was hints of it, why does the head gasket fail in certain common areas?
     
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    Plus I don't hate myself enough to try doing that.

    Possible? Maybe.

    IF you do LOTS of these, it might be worth it. Otherwise I have learned that you can waste a bunch of time with shortcuts.

    All it takes is messing up the RTV seal in one spot when going together- oil leak. I prefer to have room to work.

    Posted via the PriusChat mobile app.
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Head gaskets are often failing on the strip between 1 and 2. With the small EGR passages in the intake manifold, clogging tends to progress unevenly, with the cyl 1 passage first to completely clog.
     
  5. ToyXW

    ToyXW Active Member

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    There are so many variables that it would be impossible to say without a rigidly controlled experiment. At this point, these cars are old enough that's never going to happen.

    The top tier part of the gas equation minimizes the formation of deposits. Deposits inside the combustion chamber increase the compression ratio and form irregular shapes which radiate more heat. Both of those will make pre-ignition more likely. Higher octane makes preignition less likely.

    A knock sensor only senses knocks after they have occurred. The computer then detunes the engine until it goes away. Every so often it tries to bring the tune back to the original and if it senses another knock detunes again. So the knock sensor will prevent immediate damage, but you will still have cumulative wear/tear over tens of thousands of miles.
    EGR partially fills the chamber with basically inert gas. This allows you to use less fuel without creating as much heat as you would if you used the same amount of fuel mixed with 100% air.

    What is really bad on the prius is the EGR ports don't clog evenly so you can have #1 or #2 almost completely clogged without triggering a total egr flowrate check engine light. This makes #1 & #2 run hotter than 3 &4 and makes it more likely for knock to occur in those cylinders.

    Again damage doesn't happen immediately because the knock sensor detunes the whole engine, but it is cumulative. Add to it original coolant that has grown acidic and the gasket begins to loose its sealing coating everywhere the coolant touches. Every time a knock occurs, the head lifts slightly and the coolant reaches new ground, eating away more and more coating until it makes a complete breach to the cylinder. That's my personal theory anyway.

    It fails where the gasket is thin, under competing pressures (cylinder vs coolant), and farther from the clamping force of the head bolts. This tends to be right between 1&2 at the coolant port
     
  6. PriusHead05

    PriusHead05 Member

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    I have 210k mi. on my 2012. It is original everything except for the small 12 volt battery. As far as I know, the EGR system has never been cleaned. Everything is in great working order, other than the TPMS. I think it is dependent on the driving conditions and where in the country you are. For the last half of my Prius's life, it has been driven highway miles. And for three fourths of it's life, it's been here in Florida. Some HGs last 60k mi. and some last 260k mi. It's all over the place on how long they last.
     
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  7. CR94

    CR94 Senior Member

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    At 100851 miles on the odometer, I checked pH of my coolant, using pH paper. By that method, the old coolant was indistinguishable from new. At 106558, I paid the dealer to perform a "coolant flush" anyway, while wondering whether it would make any difference.
     
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  8. CR94

    CR94 Senior Member

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    Yeah. That surely depends heavily on how the engines are used, the drivers' habits and circumstances, etc. Mine is showing less severe EGR blockage than many others do a similar mileage.
     
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  9. ASRDogman

    ASRDogman Senior Member

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    The purpose of changing the oil, coolants, etc., is to remove it BEFORE it breaks down to the
    point it is not doing it's job.
    If you wait until it's at the point it no longer is protecting, damage is being done.

    I drive the Prius like a Prius. I want the most MPG I can get. When I first got my Prius I drove
    60 mph. Because that's how I was driving my van, to get the most MPG as I could, and to reduce
    oil consumption. And I wanted to see how many MPG it would get. I averaged 48 mpg.

    The trade off was, it took longer to get where I was going. 85% of my driving is on the highway.
    After a month, I drove 70 mph. My mileage dropped to and average of 43mpg.
    And my oil consumsion went up. I was using about 1qt between 10,000 mile changed when
    60mph. It went to 2qts driving 70mph.

    Now I drive 65mph. I get where I need to go faster, average about 47mpg, use about 1.5 qts of oil
    at 7500 mile oil changes. I can live with this!

    First time I cleaned the egr system (138,00miles) the cooler was clogged, but just sooty. I cleaned it with oven cleaner
    and just the jet stream from a hose. The next time I cleaned it at 200,000 miles, it was partial clogged with carbon
    and soot. I had bought a spare cooler that wasn't clogged, just sooty, that I cleaned to make the job faster.
    It took a few oven cleaner used to clear and clean it.

    The last time was at 268,000, it was clogged with soot, but very little carbon. I haven't cleaned it yet, but will
    soon because I'll be pressure washing the house soon.

    Some just getting use from their equipment, depending on how their useage.
     
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  10. Bill Norton

    Bill Norton Senior Member

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    "How the engines are used"? They're used to propel the Prius down the road.
    The choices are City or Highway driving. What am I missing?

    How do you know your EGR cooler 'is showing less severe blockage'?
    I'm asking because I want to have my head gasket last a long time, like below!

    This is encouraging to read!
    You don't say if you removed the intake manifold and blasted out all the tiny egr tracks at each cooler cleaning.

    I'm not clear on your last statement about usage. Are you saying your slow driving style has effects on the head gasket life?
    The interstate vacation trip I like to take has a long stretch where the speed limit is 80 MPH.
    I'm not driving 65 MPH when I'm trying to get across Kansas.:unsure:
     
  11. ASRDogman

    ASRDogman Senior Member

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    The egr circuit consists of the cooler, valve, piping, and the intake manifold.
    If you drive the Prius like a Formula 1 car, it will not last as long.

    Drive as fast as you want. It's your car. Just know that you'll be burning more oil and fuel
    and causing more stress on the engine.

    Just because you can do something, doesn't mean you should.
     
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  12. Bill Norton

    Bill Norton Senior Member

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    So, do you clean the whole EGR system at the miles noted? Or just the cooler. It's not clear.

    Saving a few bucks on oil and gas is a good thing, but I factor in hours behind the wheel also. Especially if on vaca!
    If you go down that road,,, you know how wasteful 65 mph is compared to 55 mph?
    And how wasteful 55 mph is compared to 45 mph,,, etc. etc. 45 mph is legal on interstates!
     
  13. Mendel Leisk

    Mendel Leisk Senior Member

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    I don’t think driving habits matter much; the EGR system always clogs, and will need cleaning, or your head gasket will blow. It’s right up there with death and taxes; we’re Toyota’s test subjects on that front.
     
  14. Bill Norton

    Bill Norton Senior Member

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    Is this proven?
    What about this post from above? :"I have 210k mi. on my 2012. It is original everything except for the small 12 volt battery. As far as I know, the EGR system has never been cleaned."

    So we have one at 210k mi and no EGR extra 'off the books' service.
    And one with 268k mi with 3 of these EGR services performed. But this car is limited to driving 65mph, if that helps.

    If it is a proven fact, why has toyota never addressed this in maintenance recommendations?
     
  15. ASRDogman

    ASRDogman Senior Member

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    There is no sense in only cleaning part of the system.
    Like changing half the oil.
    It's not as hard as everyone is making it out to be. Just follow the videos, and don't rush.

    And while you're at it, get some MAS cleaner and clean the sensor. Don't use carb cleaner!
    You'll ruin it.
     
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  16. ASRDogman

    ASRDogman Senior Member

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    I think you are stressing too much over this.
    People don't change there oil for 20,000 miles. It's there vehicle.

    People can say anything they want. My personal OPINION is it didn't go that many miles
    without service. JUST MY OPINION!!!!

    A clogging egr cooler is a KNOWN issue on the 3rd Genertion Prius.
    If 1 or 2 in 10,000 don't have a problem, but 9998 do, what side of the odds do you want to be on?

    It won't hurt to clean it, but the odds it will blow the head gasket and/or cause a blown rod, are too high.

    Emission's warranty is 50,000 miles. After that, a manufacturer doesn't have to worry about it.
    I supposed if enough people starting flooding Toyota and the press and news outlets about it, they
    "might" do something about it. But probably not.
    And they actually did, they made a 4th Generation Prius!
     
    #56 ASRDogman, Aug 14, 2022
    Last edited: Aug 14, 2022
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  17. rjparker

    rjparker Tu Humilde Sirviente

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    Driving fast evaporates all the water and fuel out of the oil which can be substantial, especially if you allow long periods between oil changes. You then find out your engine is not the unicorn that does not use oil. It is better to change that stuff sooner than later even though today's pseudo synthetics are good. Regardless, gen3 engines have design flaws in the cylinder cooling, piston rings, egr, pcv, intake, etc which were fixed in gen4.

    Gen4 Cylinder Spacer / Insulator
    Prius gen4 cylinder coolant.jpg
     
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  18. Bill Norton

    Bill Norton Senior Member

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    Interesting! Thanks for the look at New Tech!

    My question is: Is the Block and Head different with Gen4 compared to the Gen3? And the actual head gasket?
    I know about the different plumbing and location of the EGR cooler/system.

    I am stressed about getting a $2500 bill for a head gasket replacement on the '10 Prius w/122k miles that I'm about to buy.
    But not stressed enough to take a chance on spending 4 times as much for a used Gen4, and then find out nothing has changed in the head gasket design.
     
  19. rjparker

    rjparker Tu Humilde Sirviente

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    Plenty has changed in gen4 and the results are speaking for themselves. People usually use gen3 intakes and egrs on their gen4 retrofits for wiring and computer compatibility.

    If I were buying a gen3 today, it would be a late 2014-2015 hatchback or a late 2014-2017 Prius v, both with updated pistons and rings. In reality I would not buy any gen3 unless it was a smoking deal where $10k to repair a year later would be acceptable. Or, if it already had a rebuilt engine, new brake booster, inverter etc I might consider a good deal.

    Late 2014 means a 2014 with a vin higher than these using the last six digits:
    Prius 2014 Vin Production Change.jpg
    Note the Prius and Prius v wagon have two plants using different sequence numbers.
     
    #59 rjparker, Aug 14, 2022
    Last edited: Aug 14, 2022
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  20. CR94

    CR94 Senior Member

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    Do you really think it doesn't matter whether an owner averages over 70 mpg, as some claim, or can't manage better than half that, as others claim? Or does or doesn't make a habit of pushing the engine hard when it's cold (and running rich, when exhaust tends to contain more soot)? Or accumulates mileage mostly in short trips, or in long ones? Or does or doesn't like to cruise at 80+ mph?

    Do you believe the wide variation in mileages at which people have reported head gasket failures is due to entirely to chance or mysterious manufacturing variations? Why do you figure EGR flow test figures people have reported here are so far from a smooth curve, plotted against corresponding odometer readings at the time of failure?
     
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