Hot brake rotors(disks) , replaced everything, its still hot

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by ToyotaCoyotta, Jul 10, 2025 at 12:01 PM.

  1. ToyotaCoyotta

    ToyotaCoyotta Junior Member

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    Prius 2009 Europe, xw30, currently have 155000 kilometers

    I noticed that my front left break rotor is getting hot after I drive so I replaced rotor, pads, re-assembled the caliper (Cylinder and two bolts are moving like they should),

    However It was still getting hot after I drive a short distance

    This time I was even seeing smoke coming out so I consulted with some people who suggested me to change the wheel bearing & hub assembly so I did, but the disk is till heating up...

    Where should I look for the issue? Already spent like 300 Euro and I still have the issue....
     
    #1 ToyotaCoyotta, Jul 10, 2025 at 12:01 PM
    Last edited: Jul 10, 2025 at 1:31 PM
  2. ASRDogman

    ASRDogman Senior Member

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    I think you should have figured out WHY it is getting hot before wasting money on guessing....
    It could be ABS related, or a defective brake hose. Rubber hose.

    If you had posted this in the 2nd generation Prius section you might have someone else with
    the same issue that could help.

     
    PriusCamper likes this.
  3. ToyotaCoyotta

    ToyotaCoyotta Junior Member

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    Well I took it to the mechanics and they firstly changed the discs and pads, then they told me its bearing but I refused to believe and reassembled caliper, but it didnt work so i changed bearing too… I was also told it cant be the hose because It would return a Dtc fault if it was not giving or receiving brake fluid
     
  4. ASRDogman

    ASRDogman Senior Member

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    It shows you have a 2006 Prius.... Generation 2
    This is the 3rd Generation.....
    NOT a huge dear, two different vehicles and issues... and repairs

     
  5. ASRDogman

    ASRDogman Senior Member

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    Take it back and get your money back. Legally, if they tell you "this" will fix the problem,
    and it doesn't, you do not have to pay for it.
    Then take the car to honest place.
     
  6. ToyotaCoyotta

    ToyotaCoyotta Junior Member

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    where does it shows I have a 2006 prius, I have a gen 3 2009
     
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  7. ToyotaCoyotta

    ToyotaCoyotta Junior Member

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    Its eastern europe, there are loads of mechanics who dont give a fk and you cant do nothing
     
  8. Tombukt2

    Tombukt2 Senior Member

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    Xw30 that's the 2z head gasket cars . Bad caliper or stuck not moving valves In abs system . Hub almost never . Folks do this hub thing a lot.
     
  9. ASRDogman

    ASRDogman Senior Member

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    That's what it showed before you changed it....

    And before you added the 2009 to your original post....

    Being sneaky didn't work....

    But whatever, you need to take your car to someone who knows what they are doing.


     
  10. PriusCamper

    PriusCamper Senior Member

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    Actually the Gen3 was introduced in Europe in 2009, and not till 2010 in US, so OP is posting in the right place.
     
  11. ChapmanF

    ChapmanF Senior Member

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    If you raise that corner of the car and try to turn that wheel by hand, does it turn relatively freely, or with heavy drag?

    If with drag, and you then open the bleed valve of that caliper, does some fluid escape? Does the wheel turn more easily after that?

    Does just a small amount of fluid escape, or more of a sustained stream?

    Tests like these can give you ideas. Using a scan tool to watch the pressure reading in that line in real time can give you ideas. You can also buy pressure transducers, and adapters to attach them at the bleed screw taps, and observe their pressure readings.

    It is helpful to know at least whether the drag is because of fluid pressure acting on the caliper, or the fluid pressure is properly released but the caliper in some mechanical way is not releasing.


    Edit: note: if it's a front corner of the car, you also need the other front corner raised before you can turn the wheel. (The other front wheel will turn the other way ... so there will always be more effort involved than just turning a single free wheel.) Or, you need to get the car into Neutral instead of Park (which requires going IG-ON, and then you can't simply power off with the button again because that shifts back into Park. If you just pull the fat white wire in the underhood fusebox, you can make the car immediately lose power without shifting back to Park.) Then, you're not spinning another whole wheel/hub/rotor assembly, but you are spinning MG1 inside the transmission, so it's still noticeably more rotating mass than just a single wheel.
     
    #11 ChapmanF, Jul 10, 2025 at 4:46 PM
    Last edited: Jul 10, 2025 at 5:12 PM
  12. ToyotaCoyotta

    ToyotaCoyotta Junior Member

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    Thank you for you reply.

    Update: I bought a used caliper and replaced it, and guess what... the front right rotor started heating more than the front left... I am so confused now.. seriously..

    I came to a conclusion that it's not the caliper issue, so I decided to return the old caliper back to the place(it's actually way better condition visually because my car only has 155000km, but I refer to it as the old one because it was here before)

    I used a pole and seat to depress the brake pedal and opened the bleed valve, then closed it, did this a couple times

    Now with the original caliper back in place, when I drive it doesn't get as hot as it used to, because initially at one point after driving 10km there was smoke coming out.. Now the issue doesn't seem AS BIG as it used to be, however when I touch the rotors I can hold 3seconds before my finger gets hot on the right one and only 2 seconds on the left one, so the issue is still there.

    I read the internet a lot and I have Techstream 16 so I decided that I need to perform the air bleeding procedure with Techstream which I did, I had my friend to help me, I bleed every single wheel in order techstream suggested and then let Techstream bleed the air from ECB, there were 6 steps where it was beeping, every time I heard strong air pressure sound and I had to press next every time after pump sound stopped.

    After air bleeding procedure was completed it seems like there is a positive change because initially I would feel a slight resistance when the car is just rolling on D(not pressing gas pedal) and now It seems that there is no such issue anymore.

    However after I came back home after like 30km ( I tried to avoid breaking as much as I can, only when really necessary )
    The front right disk is pretty hot(I wanna take my arm off after a couple of seconds), while the front right is only warm (I can hold my arm as long as I want without any issue)

    I think it's worth to mention that initially when I noticed the problem (unusual resistance when rolling on D without pressing gas pedal) I have lifted my Front LEFT side with a jack and I couldn't move the wheel with my hands, it was almost impossible, I tried the same with Front Right and everything was fine so when the first mechanic suggested changed brake rotors and pads the front left wheel brake pads (or atleast one of them) was really worn compared to front left wheel, which is why I agreed on changing them in the first place.


    At this point I am very confused on what to do next...

    I will probably try to drive again and if the wheel will be hot again I'll try to lift it with a jack and spin it, if there's resistance I will then try to open the bleed valve and see if it helps to solve the dragging issue ( If I understand correctly I don't need to press the brake pedal for this test, just open the bleed valve in order to indicate if there's pressure which causes the drag?)

    I was considering on changing the brake line on the left side, however the mechanic told me " There is no way it's brake line because if it would be you would receive a DTC"



    Appreciate any further help because trusting mechanics is hard in city i live in, they just gamble my money by guessing on "what could be wrong" instead of diagnosing it as we see from their decisions to change brake discs, pads, bearing & hub & support
     
  13. ChapmanF

    ChapmanF Senior Member

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    I have read descriptions of rubber brake hoses deteriorating inside so the rubber makes a sort of one-way valve getting in the way of fluid returning from the caliper. It is not anything I've ever seen for myself, but it has been written about.

    Of course if that were the case, and you were watching the brake line pressure on an OBD-II scan tool, you could see the pressure drop to zero when released (because those pressure sensors are located in the actuator), but if you had added a sensor of your own in a bleed-screw adapter, you might see a non-zero pressure there.
     
  14. ToyotaCoyotta

    ToyotaCoyotta Junior Member

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    Interesting approach, It would be really good to see the pressure in the bleed valve, however I am really unfamiliar with such a tool called pressure transducer, where and which one to buy, let alone find the bleed-screw adapters,

    I did try to find the pressure of specific cylinders in Techstream but I wasn't able to do that, I just couldnt find/understand which data parameter is that, luckily I made pictures, hopefully its good enough to read through
     

    Attached Files:

  15. ChapmanF

    ChapmanF Senior Member

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    This example is a kit that includes a mechanical dial pressure gauge and six different threaded adapters such that one ought to match the bleed screw tap:

    American Made Sure Stop Brake Pressure Gauge Kit; 0-3,000 PSI. A1704 | SSBC-USA

    The mechanical dial, of course, may not be convenient to read while attached directly to a bleed screw fitting. Something like a Dwyer 628 transducer (chosen with a threaded fitting the same as the pressure gauge, and a suitable pressure range) can instead convert the pressure to an electrical signal on wires you can route into the cabin and watch conveniently on a meter, datalogger, etc.

    My bad. I keep seeing 2009 for your car and thinking about gen 2, which I believe had separate OBD-II readings for each line pressure, but yours is really a gen 3, which does not.