Featured Are Brake Bleeds necessary?

Do you have pictures of these rudimentary tools? I just finished the transmission fluid replacement and have some vinyl tubing left over.

I’m assuming my car never had any brake fluid changed and I’m at 111k miles. DIY’ing a vacuum bleeder with recycling bin scraps is my idea of a good time.

 

Recently started thinking it must be getting close to 3 years on the brake fluid (Toyota Canada is 3 years or 48k kms (~30k miles), checked my log: ah whoops, coming up on six years.

I’d purchased a couple of pints of Toyota DOT3 a week or two back, got into it yesterday, with the car up on jackstands for snow tire swap.

my wife helped, pushing brake pedal, good to have all windows rolled down.

There’s a link in my signature, more info on brake fluid change, earlier in this thread. (On a phone turn it landscape to see signatures).

my illustrious kit:



Invalid mode:



various:

 

I couldn't get a bubble free stream on the right front brake on my MINI. Car guy suggested a gravity bleed. Just crack it open and let it sit. Worked.

 

Fronts on the Prius are similar to regular car, you have to blip them opened/closed fast while assistant pushes brake pedal. At least a dozen times per. Rears you do similar but can leave open till cows come home, system runs a pump to keep constant flow.

 

I don't understand, but that's okay.

One time, a long time ago, I used something called VAGCOM to activate the abs pump on my VW to bleed the brakes.
I guess there may be a couple apps for Toyota? Techstream? Haven't looked into it. Will be awhile.

 

A new page in the thread, a new place for a reminder that "brake bleeding" and "brake fluid replacement" are not the same thing, so to always be clear which one you are thinking of.

The key difference is if there are bubbles, you have to bleed. If there are no bubbles, and you want to replace (most of) the old fluid with new, you can do that as fluid replacement—as long as you make sure nothing you do lets in any air. (If any air gets in, you're not doing fluid replacement anymore, and you must bleed.)

You can get away with familiar "old school" methods for fluid replacement. You won't get all the old fluid out, because some is behind valves your "old school" method won't ever open, but it's no big deal to leave a bit of old fluid behind.

If you've got bubbles but you're positive they aren't anywhere in the system except the lines out near calipers, you might also get away with some old-school method.

If there are bubbles and some of them might be in the underhood parts of the system, you have to bleed using a scan tool that can command the car to do that. In the process, at the right times, the car will switch the valves that your old-school methods can't control, so you get the bubbles out of all the places. Unlike leaving old fluid behind in those places, which isn't much of a problem, leaving bubbles behind is a problem.

 

In the MINI's front/right brake case I mentioned above, it seems to be an issue with other F56 owners as well who were merely changing the fluid. One person theorized it was because of the design of the reservoir-something about having to keep it above a divider...maybe. I went through a few additional containers of brake fluid before I happened upon the gravity method. I was using two types of a suction method as well as the foot pump method. My next step was a pressure bleeder.

I do think you want to replace the brake fluid at the recommended intervals because it attracts water and causes rust of the brake lines. Why they're not stainless, I don't know.

 

CuNiFe is nice, and easy to hand bend. My preference any time I fix a brake line without the official replacement.

 

@NutzAboutBolts video might clarify. I followed the order per repair manual (front/right first, then go around counterclockwise), but other'n that:

^To keep ahead of Chap, it should be called "replacement", not "flush".

The "old school method", for brake fluid replacement, from the gen 3 repair manual, is attached.

A couple of gotchas with :invalid mode":

1. parking brake must be set
2. to shift to Neutral you need to depress brake pedal

 

This is what I didn't understand, for the rear brakes?

 

There is a pump that stores pressurized fluid in an accumulator and runs as needed to keep the accumulator pressure near target.

The rear brakes operate from that pressurized circuit. Open a rear bleeder with the pedal depressed and the pump will keep fluid shooting out for as long as you want. Or long enough to drain the reservoir to the bottom and suck in gobs of air, whichever comes first. (If the latter happens, you're not doing replacement or flushing anymore, and you'll need the tool to do bleeding.)

The front brakes are operated two ways: by one hydraulic circuit that works just like the rears, and a separate one for fail-safe use, that you have to bleed by pumping the pedal, just like in grandpa's car.

When you do a full brake bleed procedure, it has you do both front brakes twice, once each way, to get the air out of both of those circuits. (And the fronts, when the pump is running, will empty the reservoir even faster, because those lines are short, low resistance, and the fluid comes gushing out.)

When you do replacement with the simpler procedure, you're only working one of those circuits, and it's the one that doesn't work like the rears.