How to bleed engine coolant loop with Techstream?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by pasadena_commut, Feb 20, 2022.

  1. pasadena_commut

    pasadena_commut Active Member

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    I keep seeing posts that say to use Techstream when bleeding the engine coolant loop, but I have yet to find a post that describes the procedure.

    Where is the bleed procedure documented in the repair manual? (I have the PDFs but not a master index.)

    What is the menu/button/tab path within techstream to whatever they call the bleed routine?

    Also, how long must an Allen key be to reach the bleed valve on the top of the radiator? Mine are all the L shaped type so they don't have a lot of reach.

    Thanks.
     
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  2. ChapmanF

    ChapmanF Senior Member

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    While Techstream has purpose-built "bleed procedures" for the brakes, I don't think it's got anything quite like that for burping the coolant.

    I think the most you're looking for there is how to enter maintenance mode (so the engine won't shut off while you're trying to burp it), and the "enhanced OBD-II active test" to run the coolant heat storage tank water pump.

    Maintenance mode you can also enter by doing the right kind of dance with the go pedal and shift knob, but for the thermos pump, you pretty much do need the scan tool.

    If you have the repair manual in PDF but no table of contents is showing up, you could try a text search for "ADD ENGINE COOLANT".

    Will the long end of your L-shaped wrench reach?
     
    #2 ChapmanF, Feb 20, 2022
    Last edited: Feb 20, 2022
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  3. Elektroingenieur

    Elektroingenieur Senior Member

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    In the 2007 Prius Repair Manual (RM03Q0U) (more info), see the topic Engine/Hybrid System: 1NZ-FXE Cooling: Coolant: On-Vehicle Inspection. In older editions, it’s towards the beginning of the CO (1NZ-FXE Cooling) pages.
    As @ChapmanF kindly notes, the Toyota Techstream diagnostic system doesn’t have an air bleeding function, as such, for the engine coolant. Instead, the procedure just tells you to run the water pump and then the engine.

    The 2007 Repair Manual was written for users of Toyota’s earlier Intelligent Tester (Diagnostic Tester) device, but the 2008 edition gives the Techstream path “Powertrain / Engine and ECT / Data List / Activate the Water Pump.” I think this has a misprint, however: “Data List” should be “Active Test,” since you’re controlling the vehicle, not just observing its status, and indeed, the path is given with “Active Test” in the procedure for diagnostic trouble code P2601, elsewhere in the manual.
     
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  4. pasadena_commut

    pasadena_commut Active Member

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    Found it around CO-7. Note in the version of CO I have it gives the link to "inspection mode" as IN-5, whereas it is actually IN-35 or IN-36. To start it from "intelligent tester" it is: "Powertrain, Hybrid Control, Active test, Inspection Mode -2WD inspection".

    I see that now. For some reason many posts state that it is much easier to do this bleeding using Techstream, but since all it can be used for (at least initially) is turning the water pump near the thermos on for 30 seconds at a time, that doesn't seem like much of an advantage over jumping the relay. Especially since the latter can be done while standing next to the engine compartment, whereas one would have to get back in the car to trigger techstream. At least I would, the cable on the tester isn't long enough to reach around to the front of the car.

    Thanks!
     
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  5. edthefox5

    edthefox5 Senior Member

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    Do not even think about doing that. It’s an airlock nightmare.

    All you need to do is dump the rad. It’s got a dump petcock on the drivers side behind the hoses on the bottom of the rad, Dump it throw in a gallon of LLC. Drive away.NO AIRLOCK NO BLEED NO TECHSTREAM.

    Do it again in a few weeks. Then if you don’t like that do it again. It works.
    Engine coolant is not a big deal on this car.

    The G2 Prius is very easy on the engine coolant. But very hard on the inverter coolant so concentrate more on that and it’s good bang for your buck as your mileage will increase with pristine inverter coolant and will greatly extend the life of the inverter pump.

    The G2 Inverter is the heart and soul of this car. Keep it happy.
    I changed my inverter coolant 3 times over 15 years with this car it’s easy.
    Always threw in a bottle of Redline Water wetter too with every change.
    Inverter loved it ran very cool as I checked it with an IR thermometer.
     
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