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Bad gas or headgasket?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Mo1990, Feb 21, 2024.

  1. Mo1990

    Mo1990 New Member

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    Hi all, long time lurker, first time poster.

    I have a 2012 prius II with 156k miles, sadly I’ve been sticking to the 10k synthetic oil change routine. Two major services done in its lifetime (at 80k and at 140k). Always filled up with the cheapest gas I could find (Thrifty brand). Brand new OEM cat (and cat shield) and exhaust installed around 150k, a $3.5k bill that my insurance covered.

    Recently I got the dreaded shake/rattle upon the ICE starting up. The check engine light came on for misfires in three cylinders.

    I changed the spark plugs, they were about five years old so it seemed like a good place to start.

    The rattle got worse, and it was consuming a lot of coolant, so I took it to a mechanic. He initially thought it was the fuel injectors but after a more thorough inspection, he said the engine is gonna be toast soon.

    Before he told me that, my tank was about halfway empty, and I added a bottle of Techron High Mileage and filled up with Chevron.

    Now 250 miles later, the rattle is gone, it no longer chugs coolant, and the check engine light has gone away.

    Is there any chance that bad gas could’ve been causing this issue? Do you guys think I could still pass CA smog if the engine light stays off? Still getting 48MPG easily.

    I plan on driving it until the engine goes and then swapping in a JDM motor.
     
  2. Tombukt2

    Tombukt2 Senior Member

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    Maybe a good time to look at your EGR cooler and it's pathway which unfortunately goes right into your intake manifold and those little ports in the intake manifold main ports are known to get crap in them and slow down the flow of EGR which the Atkinson cycle engine is dependent upon to run properly without it you get the rattle and the imbalance shaking and so on apparently this is the case so maybe something got moved or pushed with the techron little bit of cleaning now take it a step further I guess or go to the junkyard round you up the intercooler for the EGR gas It's a silver thing since it's right on the top of your car Go buy one from a junkyard get the metal pipe that comes out of the intake manifold and goes into that cooler assembly were buying and maybe get the plastic intake manifold if it's easy to get that way there you can have all those parts cleaned like new and ready to go so on a Saturday midday you can go out unbolt all that mess off your car put on the brand new clean stuff fire up the car see what you got You can also use the Toyota software before you do this and you can measure the flow of the EGR in HG that's going through the system right now and I think it might even show you what ideal is or it's posted here and then you can see how bad you are now and then when you put the clean stuff on see how much it improved obviously with the new numbers for the cleaner parts and a lot of times that will stop your rattling business of course if you do in fact have a head gasket leak You're heading for that JDM engine a lot sooner I have a JDM engine right now that's doing the same thing your car is doing It was doing the same thing in this particular car before this engine anyway yeah I just giving up on the generation 3 for that issue but yeah put a clean EGR setup on there and see what happens of course if you wanted the gate any of this you can just take a camera and look down each spark plug hole usually it's going to be number one and see if you can find any droplets after the car's been sitting say you know an hour wip out the windshield wiper tray pull the coils and plugs stick the inspection camera start with number one obviously and have a look in there real good You see any kind of drops that's water You need not worry anymore about your rattle but that head gasket's going to cause a bent rod if you're not careful.
     
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    Due to theft, or it failed?

    Misfire codes, coolant loss and 156K. I'd be thinking head gasket. But everyone seems to try spark plugs and coils first.

    EGR not cleaned?
     
  4. Mo1990

    Mo1990 New Member

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    Theft, got em on camera but couldn’t read their plate, they were able to cut out the cat in about 90 seconds. Insurance wanted to replace it with a generic cat but only the OEM cat is legal for CA smog, so they covered it. Paid a few hundred out of pocket for the welded cat shield.

    The mechanic mentioned coils at first too. Wonder if they’re worth replacing along with cleaning or replacing the fuel injectors, or if I should just save my money towards a JDM swap. The JDM engines go for around $1,300, was quoted $800 for labor, does that seem fair?

    I went to a well reviewed Toyota shop for the last major service, they cleaned the EGR, flushed coolants, etc.

     
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  5. MikeDee

    MikeDee Senior Member

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    What explains why you were losing coolant and now you aren't? Was there a coolant leak that was fixed (hopefully not by a stop leak chemical added to the coolant)? Bad gas can't cause loss of coolant.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    That crossed my mind too.
     
  7. Mo1990

    Mo1990 New Member

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    No idea. The coolant tank was nearly empty, so I filled it with Toyota pink antifreeze, and a week later it was nearly empty again. Filled it up again, this time with Peak asian vehicle antifreeze (also pink), and 2-3 weeks later its still at the “full” line. I’ve been driving a lot more recently too.

    Haven’t done anything since this issue started except change the spark plugs, switching to Chevron gas and adding a bottle of Techron, and adding a quart of motor oil since it was a little low.


     
  8. Mo1990

    Mo1990 New Member

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    Update: I just passed the California Smog inspection too, thankfully.
     
  9. Brian1954

    Brian1954 Active Member

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    Has the high temperature light on the dash ever come on when you were driving the car?

    Check around the plastic coolant tank for any evidence of dried coolant. One possible reason that you were losing coolant is a failing engine water pump.
     
  10. Mo1990

    Mo1990 New Member

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    Only once, for a few seconds, when the coolant tank was very low the first time.

    Damn, that whole area is covered in dried coolant since I didn’t have a funnel and spilled a ton when I last filled the tank.

    That’s a good tip though, didn’t think of that. Probably a good idea to replace the water pump considering the mileage either way. They’re pretty cheap too.


     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Maybe stop leak product added by the shop that “cleaned his EGR system”?
     
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  12. Brian1954

    Brian1954 Active Member

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    Yes, I would change the engine water pump ASAP.

    After you remove the old water pump, try spinning the impeller by hand. Is there resistance to it spinning.? If so, try to remove the impeller and inspect the white plastic that is around the magnet. Is the white plastic split? Better yet, upload a photo.
     
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  13. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah, 156K miles, it's time to change engine coolant pump, aka water pump. If you're doing coolant changes by miles, 150K is the second engine coolant change (and first for inverter coolant, in the States). Timely, maybe even pushing it.
     
  14. Mo1990

    Mo1990 New Member

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    The shop did that work over a year ago before this issue started didn’t have any leaks back then…not that I trust any shop 100% haha
     
  15. Brian1954

    Brian1954 Active Member

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    Personally, I would only purchase an OEM water pump. They are made by AISIN for Toyota. Do not buy a cheap generic pump unless you want to change it in a year or two again.
     
    #15 Brian1954, Feb 22, 2024
    Last edited: Feb 23, 2024