Help! Accidentally let all fluid drain from rear drum brake line and bleeding won’t refill it.

Discussion in 'Gen 2 Prius Technical Discussion' started by PriusThatTows, Oct 24, 2020.

  1. PriusThatTows

    PriusThatTows Junior Member

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    I was trying to replace drums and didn’t pinch off the brake line. The baggie i ziptied to the line has like a pint of brake fluid. I thought, “No big deal. I’ll just fill reservoir and bleed it all through”, but that isn’t working. I am getting a tiny trickle of fluid out the bleeder valve and into my homemade bleeder bottle setup. I’m hoping its a simple issue like gunk is clogging the line in the wheelwell and I can cut, flare, and attach a flexible line... or perhaps in moving the line out of the way I kinked it which could be fixed the same way. But... I’m worried that draining the line all the way back to the master cylinder might have damaged something. I know that the master cylinder/abs assembly is over $1000 and multiple hours to replace.

    Is there some obvious reason it might not be bleeding that I’m missing? I’ve tried “pump, open, close, release” like 50 times now.
     
  2. SFO

    SFO Senior Member

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    Unless you have techstream handy, try the "prius rock" method for bleeding the rears.

    100K maint - 1

    [​IMG]
     
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  3. sam spade 2

    sam spade 2 Senior Member

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    Assuming that it has ABS, there likely is a somewhat more complicated procedure required to get it to actually send fluid to each wheel when the car is not moving.
     
  4. ChapmanF

    ChapmanF Senior Member

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    Are you trying to bleed without using the Techstream procedure?

    I think if the system detects an unreasonable amount of fluid going down one brake line, it will leave that line valved off to avoid losing all braking, and that will prevent most faux bleeding methods from working.
     
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    On the prius, the brake actuator completely controls the brakes. When you normally step on the pedal the computers decide how much regeneration to do first, then it uses a pump to make pressure to work the brakes at each wheel. Your foot has no direct connection to the calipers or wheel cylinders. IF the actuator completely fails then there is a backup mode where the master cylinder will directly connect to each of the front brakes- you still have some braking but no boost.

    The front brakes can be partially bled using a pressure bleeder or some other manual procedure, but the rears require a scantool (techstream) or another way to tell the brake actuator to apply and send fluid to the rear brakes. There may be "work around" methods for this on youtube but I have never tried any. You also need a scantool when you have to fully bleed the actuator.
     
  6. ChapmanF

    ChapmanF Senior Member

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    A brake rock works for the rears, if the brake ECU hasn't already declared that line off-limits.
     
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