How do I air bleed engine coolant 2010 w/ air bleed valve

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Olscratch, Dec 31, 2020.

  1. Olscratch

    Olscratch Junior Member

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    So I recently cleaned the intake manifold and spilled some coolant which gave the car air bubbles triggering a hot coolant light flashing at high speeds.

    I already had this air lift system from the last time I dealt with this issue. Even after draining and using the air lift to refill the engine coolant I still am able to get it to flash a hot coolant light, though very briefly.

    Every time I've ever tried to use the little white screw air bleeder (fortunately I have strong fingers and can unscrew it without taking off the wiper cowl) I somehow end up letting more air in the coolant circuit.

    By trial and error I have figured air valve bleeding has to be done with the engine off, and the reservoir cap off, and some YouTube videos showed me the reservoir needs to be unbolted and bungee corded up high forcing gravity to push the coolant down to the bleed valve. I'm not sure if I then need to run the car to get the remaining air bubbles to recirculate around, or how many times should I have to do this. The heater has never worked well, I'm wondering if that's where the bubbles are coming from.

    Has anyone ever conquered this problem with a 2010? Is there a factory service manual that would show how a dealership would do it? I'll do anything at this point.

    Thanks and happy new year
     
  2. ChapmanF

    ChapmanF Senior Member

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    In my 2010, the reservoir has a "B" line located up above the "F" line.

    When I changed the coolant, I opened the bleed valve (I found it had a crosswise slot in it; I just found a long narrow piece of flat metal to place in the slot and turn like a handle, no need to disturb the cowl). Then I filled the reservoir to the "B" line, which is also just about the point where some coolant begins to spill out the bleed valve.

    Then, following the manual, I closed the bleed valve, burped the larger hoses a few times, checked the reservoir level and topped it back up to "B", capped the reservoir, ran the engine in inspection mode until it reached thermostat opening temperature, and let it run that way for 7 minutes or more while continuing to shake and squeeze the hoses.

    After I stopped the engine and let it cool down, when I checked the reservoir level, it was right at "F", just about as exactly as if I had filled it there myself. It seemed as if the engineers had almost perfectly calculated the volume of trapped air that would come out in the process.
     
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  3. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    I changed the engine coolant on our 2010 a few months back, left the bleed valve open (with a clear tube attached to avoid spillage). When refilling oolant started coming out a bit before I got to the full line on reservoir. I shut it, continued filling to top mark.

    Then ran the engine in maintenance mode for a good half hour (per Repair Manual Guidance). Coolant level never budged to speak of, and never did get the fans to come on. Gave up. Monitored over the next few weeks, everything fine.
     
    #3 Mendel Leisk, Dec 31, 2020
    Last edited: Dec 31, 2020
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  4. Olscratch

    Olscratch Junior Member

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    So just to be clear, once coolant was coming out of the air bleed valve you closed it then squeezed/burped the hoses while they were cold and with the reservoir cap off just like a 'normal' car. Then ran it in inspection mode (is that the same as maintenance mode?) and continued to shake/squeeze the hoses with the reservoir cap off and the bleed valve closed?
     
  5. ChapmanF

    ChapmanF Senior Member

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    In my case, I was following the manual, so I had the reservoir cap on during the time I was running the engine up to operating temperature and burping the hoses.

    During that time it just trades air for coolant in the reservoir. The reservoir starts with coolant up to B, and ends up with coolant only up to F and the remaining space filled with air that came out of the engine.
     
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  6. Olscratch

    Olscratch Junior Member

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    Ahh I see. Thanks for the response. Where can I get a manual? What's the best manual?
     
  7. ChapmanF

    ChapmanF Senior Member

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    We have a wiki page that Elektroingenieur kindly put together with a wealth of different ways to get access to the manual.

    The best manual is, well, the manual. Alternatives are ... not best.
     
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  8. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    My post has repair manual excerpts.
     
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  9. Olscratch

    Olscratch Junior Member

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    Tried using the manual, filled to B. Squeezed all the hoses, then ran it in maintenance mode and squeezed them some more. Took it for a spin last night and after 30 minutes I was still able to get it to flash hot coolant light. I don't understand how this is so easy for you guys and I'm having such a struggle getting these air bubbles out.

    Does anyone have any other ideas?
     
  10. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    You did open the bleed bolt, and saw coolant come out (as you fill) before closing?

    For next time: when taking off the intake manifold, you do need to take off the throttle body, but it’s coolant lines have enough play that there is no need to disconnect them. Just tie throttle body to the inverter conduits or something.

    Somewhat similarly, if removing Exhaust Gas Recirculation cooler, you do need to disconnect its coolant lines, but if you drain about 2 quarts of coolant (at the rad drain), the cooler will be high and dry.

    When all is reassembled, open bleed valve, attach clear tube (just to avoid spillage), and pour coolant back into reservoir. Close valve as soon as coolant starts coming out of it.
     
    #10 Mendel Leisk, Jan 2, 2021
    Last edited: Jan 2, 2021
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  11. ChapmanF

    ChapmanF Senior Member

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    Can you confirm step by step that you:

    1. Filled to B with bleed valve open, saw fluid come out bleed valve?
    2. Closed the bleed valve?
    3. Burped the hoses?
    4. Made sure reservoir was still at B or topped it off again to B?
    5. Capped the reservoir tightly?
    6. Started the engine in maintenance mode?
    7. Watched coolant temperature until it reached thermostat opening temperature, and confirmed it (by feeling hot coolant circulating in the lower radiator hose, and seeing it circulate from the small upper return hose to the reservoir)?
    8. Continued running for 7 minutes or more after confirming the thermostat was open, continuing to shake and burp hoses?
    9. Shut off the engine and waited for coolant temperature to return to ambient?
    10. Checked the reservoir level and confirmed it had fallen from B to F or lower?
    11. If it was lower, topped it back off to F?

    If you did follow those steps exactly and confirm all those points, then possibly the flashing of your overheat light is for some reason other than an air pocket.
     
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  12. hotelprisoner

    hotelprisoner Member

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    Any chance the coolant pump is failing?

    Can you confirm that no coolant leak sealers have been used in this vehicle?

    On my Gen 2 I put my front wheels up on ramps and ran the engine in maintenance mode and successfully purged all the remaining bubbles that way. On my Gen 3 I used the airlift without issue. To ensure maintenance mode brought the engine to normal temperature I ran it with the hood closed and kept the RPM up slightly, otherwise, it just wouldn’t get there.
     
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  13. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Yes. I think the bleed valve pretty much did the job though. The reservoir level “might” have dropped slightly during the long idle, near nothing though.

    For 2012 model year onward where Toyota nixed the bleed valve (yes!), I think you could temporarily pull off the topmost hose there, achieve the same function.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    The volume of the reservoir between the B line and the F line is the volume of air the engineers expect to be removed from the loop during the long idle. The manual explicitly says to make sure the level is at B before capping the reservoir and beginning the long idle, topping it off first if need be, and then to make sure it is at F or below after the engine is stopped and has returned to ambient temperature (then top back up to F if it ended up below).

    If the long idle hasn't dropped it by the amount from B to F, then presumably there is some air still to be worked out.
     
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  15. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Having another read: you are right on all counts regarding the B line, capping the reservoir and so on. I followed @NutzAboutBolts video, filled and left cap off for the protracted run. Think I managed to get lucky though (Knock on wood...): this a couple of months back, and have not had any problems, with protracted highway drives. Will keep it in mind for the 15 year change, do it right. (y)
     
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  16. Olscratch

    Olscratch Junior Member

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    Well fellas I think I found the culprit. I noticed some coolant down by the throttle body that just seemed out of place. Then by slightly squeezing that hose that I first took off to clean the intake manifold I noticed it drip out some coolant.

    So definitely a small tear in that coolant hose. I'm guessing that was what let in the air bubbles? Will change out the hose and report back.

    My prius has witnessed more head gasket sealer than should be legally allowed. I carried a can of bars-leaks with me for a while and instead of replacing lost coolant I just replaced it with head gasket repair. That's been a couple years ago though, haven't had a head gasket issue in a long time. Now I perform regular maintenance and replaced the EGR cooler a few months back to prevent a re-occurrence.
     
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  17. ChapmanF

    ChapmanF Senior Member

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    Without necessarily saying you don't have trapped air, there's a definite possibility that the overheat light you are seeing is a result of all the sealer poured in.
     
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  18. Olscratch

    Olscratch Junior Member

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    OK, so I changed out the hose with a tear in it, and a couple others. Refilled the coolant per the manual to 'B' and burped hoses etc.

    It seemed fixed for a few days but when I really got it hot, going almost 80mph up a hill it still flashed a hot coolant light at me. Also I can hear, and feel, some gurgling under the dash - really it feels like its almost right behind the accelerator pedal. I'm not sure I'm burping all the hoses. Is there any diagram or something someone can show me that actually shows each of the hoses I need to burp?


    I've changed out the radiator since using the head gasket repair. What all could still be gummed up? Should I just go ahead and invest in a new water pump?
     
  19. Mendel Leisk

    Mendel Leisk Sunday driver DIY’r

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    Try flushing with a 50/50 white vinegar/water solution. That’s recommended by one stop leak seller, as capable of dissolving the gunk. If you can find some nuggets test first.
     
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  20. Olscratch

    Olscratch Junior Member

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    I actually already tried that, then did a flush with some of the high-quality Blue Devil product w/ degreaser. No potatoes.
     
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