Leaking Brake fluid

your brake system is a "closed-loop" system - you shouldn't need to add brake fluid. You've sprung a leak someplace and it needs to get fixed ASAP. It is UNSAFE to drive. The high pressures in that system can turn partial brakes to no brakes in an instance. That would turn your car into an unstoppable two ton wrecking ball.

 

So based on a video I just watched, I would recommend removing both front side tires and from there inspect both hoses to find out if there's any leaking coming from either line. Start from there.

 

No the Prius always stops. All you need to do is walk around the vehicle and look with a flashlight inside of the wheels if there is a leak you will see a shiny oily mess generally it's going to be it a wheel usually it's the back The fronts don't tend to leak I should be interesting I bet you were just low because was being held in the accumulator or something like that brake fluid leaks in these vehicles or almost non-existent but we'll cylinders in the back will go bad or sometimes people have the drum off and they get the wheel cylinder lineup cockeyed and then they can leak should be interesting to see what you have going on..

 

There's no hydraulic brake system on Earth that stops if the fluid ain't there. And Prius brake failures where the pedal went to the floor and the car didn't stop have been reported both on this forum and to NHTSA.

I don't want to get the OP to panic; the first job is just to find out if there really is fluid leaking out. But it's not responsible to tell anybody "No the Prius always stops", especially with so little information on what their issue is.

Back to finding out what the issue is, this point is well taken:

There is an 'accumulator' (the black cylindrical tank seen on the brake actuator) that gets fluid pumped into it when the car is in use. That makes the level in the plastic reservoir lower. When the car is off, that fluid slowly returns to the reservoir, and if the car has been off many hours, you'll see a higher level in the reservoir.

So if you are trying to decide if there's a leak by comparing reservoir levels from two different times you looked, you have to be careful what times you look.

The lines marked on the reservoir for max and min are made to be checked when the system is "zeroed down" (no pressure in the accumulator, all fluid back at the reservoir). If you look when the system is pressurized, the level will be lower. (If you top up when the system is pressurized, you'll be above max once the system is zeroed down.)

The system is close to zeroed down if the car's been left alone for some days. A faster way is to use a scan tool that has the zero-down function.

Or, you could decide to always look immediately after the pump has run and stopped. That might be simpler, as you don't have to wait for days or use a scan tool. Just open the driver door or pump the brake until you hear the pump run, then wait for it to stop and look at the level then. It will be lower than the zeroed-down level, but the key is just being consistent about when you look.

Being consistent, then you can compare the levels and decide if you really think any fluid is leaking out.

(The fluid level also slowly drops as the front brake pads wear down, but that should be happening over a longer time scale than we're talking about here.)

If you really are sure the level is going down, and you've compared in consistent conditions, then there has to be brake fluid somewhere. Get the car up safely on jackstands or a safe lift and follow the brake lines all around with a flashlight. If fluid is leaving, it has to be somewhere.

Sometimes it's not where you expect it. I worked on a vehicle once where a steel brake line had a crack. It never leaked except at the highest pressure when the brakes were applied hard. Then it shot a jet of brake fluid clear across the car, and the only wet brake-fluid spot was on the far frame rail across from where the brake line was.

For safety, if you ever suspect it might be something like that, be careful how you check it. Point a camera at the spot you suggest and watch the screen while you stomp on the pedal. Or wrap the spot in rags, stomp the pedal, then go back and check the rags for a wet spot. Don't try to watch close up or feel the leak in action; a high-pressure fluid jet like that could hurt you badly.

 

Pretty much on these cars If you don't see any fluid on the inside of your wheels or on the backing plates of your rear brakes and around the calipers of your front which would be silly rare. You probably don't have a leak less you left the clamp off the reservoir when you did the ABS actuator job or something along those lines The system in the car doesn't just all of a sudden develop a leak at the wheels possibly but under the hood and all of that unless you're in the rust belt and brake lines have literally become perforated and then you'll see the shiny fluid somewhere all over somewhere and you'll have a pedal that's going to the floor very quickly and nothing in the reservoir not just a low level nothing or very empty and it won't change in a few hours if there's fluid in the reservoir and it's not leaking out on the ground and the rest of the nonsense in the car is going bad it will stop now if you have a hydraulic leak and it's all your fluids going on the ground well obviously then you'll be on the parking brake in the car can still stop but somebody has to be thinking and therein will be the problem these days.

 

Well more than a decade ago, when Toyota was having the accelerator cable sticking problem. All you had to do was throw the car into neutral or park to stop the car. I believe one instance included a state trooper that was driving and everyone in that car was killed.
The point is, you need to know your audience and not everyone can think on their feet. I've known and seen lot of doctors freeze up in an emergency situation and these are brilliant people. That's why we do trauma drills.

Just saying, I'd prefer not to be on the road with someone that's knowingly driving around with bad brakes.

 

Well we do need some kind of population control they've been throwing us different things over the years and we keep stomping them down so here we is. Too funny