Featured Are Brake Bleeds necessary?

one manual for a whole country makes no sense. why not one for the whole world? regional by climate would be better served.

 

Absolutely. Sometimes boundaries make for bonehead policy. Here in BC the 3rd gen oil change is 8000 km or 6 months. Down the road in Blaine it's 10,000 miles or yearly. Ditto for Nome, Alaska, Fargo North Dakota, lol.

The icing on the cake though: it's your car, you can override the nonsense with whatever seems sensible. Trouble is, that there's no official stance on this, so most owners just follow the book.

 

mendel, what's your take on the o/p's question, she's strangely silent.

 

I suspect she meant replacement when she said bleed? And yeah, I like 36 month or 30K miles for the latter.

I've never bothered with opening the bleed bolt when pushing in piston for new pads, and I'd wager periodic brake fluid replacement makes this more viable.

 

But "she" insists not.
You can't help someone who won't help themselves.
(And how do we know this is a female?)

 

TE="Kenny94945, post: 2531482, member: 143565"]IMO Absolutely.
A bleed, the removal of air.
If you ever raced motorcycles, one may notice the air (softness) that can occur over a race (in addition to fluid heat/ fade.) You can get a bubble, a burp, if you bleed between races, improving brake feel.
,
A flush is another issue.
Here you are replacing the old "water infused" fluid with fresh fluid.
Every two years is the standard....ignoring individual manufacturers service guides.
Also note the importance of cold and hot oil boiling points of the replacement fluid.

Now a days, bleeds/ flushes have become more difficult because of ABS et al systems.
Many vehicles require a scanner or computer hooked up to the car to correctly do a brake fluid service.

However, many of the motoring public ignores brake fluid maintenance with no ill effects, complaints or even comments about braking performance.

Good luck in your decision.[/QUOTE]
...not just a "bubble" and a "burp", but my friend Chris had a loud "BANG!" one morning from the nearside-front on his old Volvo 122
as the water in the brake-lines boiled, turning to steam, and popped the pistons out of the brake-cylinders on the front wheel! This was back in the 1970s, long before the concept of "IEDs" but I think his laundry (and that of his passengers) must have been interesting

 

was this thread started on april first?

 

Brake bleed, brake flush, and brake fluid replacement are all the same to us. You're basically replacing the fluids with fresh fluids, doesn't matter how you say it, its basically removing the old fluids with new ones. Also, if you have air in the system or water in the system, you're still going to need to bleed/flush/replace the fluids in the system. I hope that's not confusing?

 

Who exactly is "us" ??
They are not the same.

 

I've been "sitting on my hands", but yeah, I'd agree, they're not the same:

Brake fluid bleed: one corner, to release air, or perhaps while pushing piston in for a pad change. I don't do the latter, but do change brake fluid regularly, which I think somewhat negates the need.

Brake fluid flush: like any flush, implies contamination is present, involves multiple changes of fluid, to greatly reduce contamination

Brake fluid replacement: The usual, out with the old, in with the new. Pumping through about 2 pints of fluid, with the aim to replace virtually all.

 

i'll respectfully take your word for it, thank you. now all we have to do is get the correct timing to the o/p.

 

So has anybody done a brake fluid replacement? My wife's Prius is coming up on its 4th year old and I'm wanting to replace the old fluid. Is there any difference with the regenerative braking system or does the old school procedure work?

 

Watch the Nutz About Boltz video, you have to put the Prius in Invalid mode so that the brake booster will not pressurize while you are bleeding the system.

Posted via the PriusChat mobile app.

 

Ive done it a couple of times, roughly following the @NutzAboutBolts video, except following the order prescribed in Repair Manual: which is start with front/right, and go around counterclockwise (see attachment).

The “invalid mode” procedure is necessary for sure. The parking brake HAS to be on, or the mode won’t happen. Also, as @NutzAboutBolts describes, you need to push brake pedal for each shift into Neutral.

I went through 2 pint bottles of Toyota DOT3 fluid. At the start you baste out most of the reservoir fluid and refill. This isn’t noted in Repair Manual but seems sensible.

I tried to do about 4 oz on each front corner, and about 6 oz on the back corners. Watch the @NutzAboutBolts video closely, lots of good tips, regarding bleed technique with front vs rear: the fronts are traditional/finicky, and the rears you can bleed till the cows come home.

With the initial reservoir refill and all, my object was to end up with an oz or two surplus, just in case I want to fine tune the reservoir level, over the next few days (so far haven't needed to). I always aim to leave the level as it was at the outset.

For drained fluid collection I used a large Costco Kirkland mayo bottle, with a hole in lid to restrain tubing. I had a bleed bolt connection gizmo from my Mighty Vac kit; that’s the only thing I’ve ever used from that system lol. Pushed that onto clear plastic tubing, worked fine, no vacuum assist really needed.

I put the whole car on safety stands and removed wheels, had my wife help, pushing the brake pedal as needed. Have the windows rolled down so you can hear each other. You “can” do this without raising car and removing wheels I think, but it would be harder.

Without and with Techstream methods attached:

 

Depending on what you consider the "old school procedure", probably that doesn't work, but the reason isn't "the regenerative braking system", which isn't a thing.

Regen is nothing but the brake ECU and the powertrain ECU chatting with each other over a network, where the brake ECU can say "driver wants to slow this much, how much can you do?" and the powertrain ECU says "I can do yea much with the tranny" and the brake ECU says "great thanks, I'll do the rest." There isn't any part of "the regenerative braking" that has a physical presence in how the actual brakes are built.

However, the actual brakes are a modern system that combines four wheel ABS and skid control and electronic brake force distribution, a separate failsafe hydraulic circuit that doesn't depend on those, and a method of power assist that doesn't depend on the engine running. That last bit is a real physical change to how the brakes work because of being in a hybrid, but it's not because of regeneration, it's because the engine's not always running.

Because of the number of hydraulic passages and electronic valves that you have no direct control over, the only way to completely bleed the system is to go through the diagnostic utility procedure that puts it through the right paces while you follow its instructions.

In particular, it will have you bleed the front brakes twice with two different procedures, one that does the normal hydraulic circuit and one that does the failsafe one. People following "old school" procedures are generally missing one of those completely.

 

Thanks for the help everyone....doesn't look like a job above my pay grade!!

 

As mentioned in the Nutz About Boltz video, be careful not to get any brake fluid on the painted surfaces of your car.

Unless you want to test the purported paint stripping abilities of brake fluid.

Posted via the PriusChat mobile app.

 

So is it safe to assume the brake bleeding procedures are the same for the Gen 4 models as the Gen 3??

 

The Gen 4 system is, in some ways, a radical departure from how earlier gens did things (where, already, Gen 3 was more like Gen 1 with tweaks, and in between them was Gen 2 with its own version of "and now for something completely different").

You can get a sense of some of the Gen 4 differences in this thread (most of the interesting discussion starting on page 2, but the diagram appears in one of the earlier posts.) I would definitely expect the bleed procedures to be somewhat different too.

On the other hand, if your "bleed procedure" is "look up the steps in the repair manual, and follow those", then yes, that "procedure" will work just as well in Gen 4.

 

Yes I believe so.