Frequent brake actuator noise after service appointment?

I think a lot of people replace them as a pair. Do you also have to have tech stream so that you can bleed the system. What year is your car?

 

You said 'oops' but you still haven't said what year your car is ... 2005 (Gen 2) in your profile, but you are posting in a Gen 3 thread.

If your car is a Gen 3, the actuator and the accumulator are separate components.

If your car is a Gen 2, the actuator and the accumulator are combined in a single assembly.

 

Damnit all. I knew that guy did a shit job. I’ve heard someone recommend to someone else to “bleed the brakes before the actuator fails”. I’ll admit I have not the slightest how the braking system works but does this advice (given zero context) at least make sense to start with? Does air in the brake lines ever correlate with hydrolic syst malfunction? Or is that a leak?
Thanks again for your help, I know it’s an old thread… I think I even started a new one

 

2005 I’ve replied in the wrong section. I acknowledge this. I’ve reposted elsewhere. I may have techstream but no vlc also I don’t know enough about these braking systems to correctly bleed them with confidence.

 

…unless it really is as step by step as I’ve heard. What would a mechanic (not the dealership ) charge to bleed the brakes with techstream? Should I just grow up n learn this?

 

Air will make the pump have to run more frequently. It goes like this: the pump shoves fluid into the accumulator until the pressure there is very high.

When you use the brakes, the fluid is let from the accumulator into the brake lines, so the pressure is applied at the wheels.

Normally that doesn't take much fluid. It's a liquid, it doesn't compress, so only enough fluid moves to shove the pistons out and clamp the brakes on the rotors.

When you release the brakes, the pistons return and that small amount of fluid goes back to the reservoir. Eventually the accumulator pressure is low enough for the pump to run and pump it back up again.

If there is air in the lines, when you apply the brakes, more fluid has to flow out of the accumulator, because it has to compress the bubbles in the lines before it will reach the target pressure at the wheels. When you release the brakes, that extra amount of fluid gets squirted back to the reservoir as the bubbles expand again. So each use of the brakes takes more fluid from the accumulator and returns more fluid to the reservoir, and the pump has to run more often to keep the accumulator pumped up.

 

Awesome, that was such a damn good explanation I feel like now I DO know more about the brakes and should consider bleeding them myself (after a lot research of course). Would you mind watching/listening to the noise for me? Here

 

My usual browser protections would have me jumping through hoops to use that link, but usually it's not necessary. A lot of people will read through existing posts about frequent accumulator pump runs, and end up saying "but would you please listen to my recording?", and after listening, yup, those are frequent accumulator pump runs. There just isn't a whole lot of variation in how they sound.

There is one important detail, though: does it continue to cycle on and off even when you are not applying the brakes at all? If so, the bleed procedure will not be a cure, because there is some valve sticking that is allowing the fluid to keep escaping from the accumulator even when the brakes aren't in use. That's a different problem.

If the pressure holds up well when the brakes are not being used, but just needs extra frequent pumping when the brakes are used, getting any air bubbles out can help with that.

 

interesting, i HAVE heard it run when not applying the brakes. Why wouldnt that throw a code? Or is that the "hydrolic malfunction" (!) 65?

Also while sitting parked, the actuator runs ever single time i press the brake pedal. From the system you described, this doesnt seem normal at all. Is that right? Seems to match with your valve sticking idear

 

Also I know the brake pump noise is a distinct noise and all sound the same. What im interested in is this hissing vaccum sealing noise that occurs when i apply the brake pedal, right before the actuator noise , also the creaking noise as i release the brake pedal. I should add that the parking brake doesnt work and I have yet to reset it.

 

That last part is where I would direct some attention before pretty much anything else.

If you have a Gen 2, then no matter how many times we post about it here in the Gen 3 forum, it never becomes an honorary Gen 3, and it still has the Gen 2 rear drum brakes. Those have mechanical adjusters inside that absolutely depend on routine regular use of the parking brake to keep them adjusted.

The way that works is detailed more in this post. In short, as the brake linings wear, there eventually comes a time when the brake shoes have to move by more than 0.03 mm to contact the drums. When that happens, the next time you apply the parking brake, there will be a 'tick' of the adjuster. And after that, when you have released the parking brake, the next time you use the regular service brake, the adjuster will 'tock' and the shoes get 0.03 mm closer to the drums. It all happens 0.03 mm at a time, and each time takes a tick and a tock.

So you can see that, if the parking brake hasn't been getting regular use, the shoe-to-drum clearance can just keep getting larger and larger, and could be considerably more than 0.03 mm by now. The larger that clearance gets, the more brake fluid has to whoosh back there (hisss!) every time you apply the brakes, to force those shoes all the way out to the drum, and the more distance the shoes spring back again (creeeaak!) when you release the brakes; and because of the larger amount of fluid that consumes, and returns to the reservoir, on each use of the brakes, the more often the pump has to run.

The C1344 code (blink code 65) is a complaint from the brake ECU about not reaching the target rear left fluid pressure the way it expects, and there can be various causes, but it's certainly not inconsistent with the brakes being out of adjustment.

If you have heard the pump run when nobody was touching the brakes, that remains a concern that isn't laid to rest here. But we could still find out how much better things get with adjusted brakes.

 

No shit? I wouldve never guessed the e brake works likes that. This car never ceases to amaze me. Thing is, i remember the parking brake used to work a little bit a year ago, and i do still use it, even though it does nothing (goes all the way to the ground, kind of makes a click?). But in the system you describe, wouldnt that make driving with the E brake on catostrophic? Because I KNOW ive driven considerable distances with it on in both of my pri..in fact i think this is what made it stop working in one.

 

It isn't good for the brakes; it wears them down faster, may put a glassy surface on them, heats everything up, kills your mileage, and might cook the grease in the wheel bearing. But I wouldn't call it catastrophic.

Sometimes those starwheel adjusters get gummed up and won't move easily, and then the brakes eventually go out of adjustment even if you're still using the parking brake routinely. The lever will just slide up and down over the same tooth of the wheel. So you end up thinking "hmm, this used to work, but now it goes to the floor and does nothing."

If it has been doing that for a while, you may open it up and see that one tooth the lever has been polishing will be totally rounded and smoothed off, and of course you need to replace that. They are not expensive at all, just a few dollars.

Driving around with the brake on, with its tendency to cook things from heat and make a lot of brake dust, can be a contributing factor to that too.



You'll see the caption saying the 'tock' (lever descends again, turning the wheel) happens as soon as you release the parking brake. In practice, if you watch it in action, you'll likely see that doesn't fully happen until the next application of the regular brake, after parking brake is released. That's because the regular brake pushes the shoes apart with hydraulic fluid, which takes the spring force off the adjusting screw, so it can more easily turn.

 

Thanks alot for your help, I really have learned alot more than i expected (or wanted to) when i posed this question. But it's all like clicking together now...the collection of problems this prius has are intertwined and youve help shed an enormous light on them.
....So the E brake, still has me confused.Ive seen videos of people adjusting the E brake using two 10mm wrenches to turn the "adjustment screw" under the dash. Ive also heard of people adjusting the mechanism under the center console. But if im following you correctly, do you recommend pulling off the back tire and adjusting the drum brake manually (if the shoe to drum clearance is significant) first? Or to tighten the E brake first? Or in some way is it possible to adjust the drum brake using the E brake (.03 mm at a time) by applying the E brake, releasing it, then using the regular service break? I'd much prefer not to tinker with the drum brakes manually if possible.

I have little to no experience with drum brakes and honestly dont think brakes are a good candidate for my fast and loose guess and check method of learning things, they stop the car after all....I mean i already drove it to the mechanic that fixed the actuator with zero brakes at all, with that loud high pitched beeping, at 3 AM, using the barely working E brake to slow thru red lights. We take breaks for granted. So i might take it to someone to adjust the brakes, but i always chock a visit to the mechanic up as a failure on my part. But i'd love to learn and hate paying 3x the actual cost of something...we will see

How could i test to make sure there are no leaks in the brake lines, causing that decreased hyrolic pressure?What are some of those other causes you mentioned? For the (!) blink code 65.

 

So i went ahead and tightened the parking break adjuster screw under the dash all the way tight. And the parking breaks still dont work at all. What does that mean?

 

I'm sorry I didn't see your earlier post in time to stop you from doing that. If you have any memory of about where that screw was before you did anything to it, and you can sort of get it back there, that would probably be worth doing.

In the world of car DIYing, there is this weird way that goofball ideas stay in circulation forever and end up being the first information you find. The mechanism under the center console generally needs no adjustment ever unless the steel brake cable actually stretches, which generally doesn't happen unless the driver of the car is Sasquatch and has really been stomping the email-protected out of the parking brake for ten years.

Meanwhile, if the parking brake isn't holding, the reason is almost certain to lie in the adjusters between the shoes, the one place in the system where normal expected wear of the pads is normally, expectedly adjusted for. But when you do a google search you find gazillions of references to people tightening their cables because it's something they've heard about, whether or not it makes any sense.

Yes, absolutely; as long as they basically work (don't have teeth worn/rounded off, aren't gummed up and stuck) you can catch them up 0.03 mm at a time just by alternately pressing/releasing the parking brake and the service brake.

If you are doing this in a quiet enough place, you can even faintly hear the click from the rear brakes as you press the park brake pedal down each time and the adjust lever clicks up over the next tooth. This has to be in a really quiet place, and I'm usually bent over pressing the pedals with my hand rather than my foot.

When correct adjustment is reached (the shoes are within 0.03 mm of the drums), you will know because you no longer hear that faint click. The lever won't click up over that next tooth then until the brakes have worn enough to allow it.

But notice I said "as long as they basically work (don't have teeth worn/rounded off, aren't gummed up and stuck)". That's a good reason to take the drums off and at least get a look. If they are so far out of adjustment now that the parking brake has no grip and the service brakes go whoosh, that means they haven't been automatically adjusting for a long time. There might be a reason for that. Pulling the drums off would be the way to see that.

As I mentioned, the adjusters aren't over a few dollars if you need them.

Just pulling the drums off to get a look is not a complicated operation. Disassembling the drum brakes further than that is kind of fiddly if you're not used to it, but just having the drums off for a look-see is no big deal.

You can even apply the parking brake with the drums off, or have a friend do that while you watch the mechanism, and you should be able to plainly see that lever move up and click over the next tooth.

However:

Do not touch the service brake pedal while the drums are off.

In a normal car that wouldn't be a problem, and you could watch the shoes expand and the lever pull the adjust wheel down. How far the shoes would move would be limited by the pedal travel.

But a Prius is not a normal car, and it works the rear brakes from fluid stored in a pressure bottle, and the pedal opens valves and the fluid flows back there, and without the drums to stop the shoes, it will push the pistons right out of the cylinders, and that will make your day longer.

It can be a good idea to disconnect the 12 volt battery before beginning, which can protect you from such mistakes and also from being surprised by the brake system's self test coming at an unfortunate time.

While you have the drums off, if you want to watch the adjust wheel being pulled down when the shoes expand without the parking brake, you have to sort of make do by grabbing the tops of the shoes and spreading them apart a little bit yourself.

 

Awesome, thanks for your very thorough explanation. My apologies for asking the same thing 10 different ways. I, admittedly, make things alot more complicated than they need to be sometimes.