How to bleed brake on 2005 Prius?

<div class='quotetop'>QUOTE(seasalsa @ Nov 25 2006, 10:53 PM) [snapback]354100[/snapback]</div>

Same thing you did to get yours dirty. The difference is, I looked at mine. Can't tell if you meant to be humorous or condescending, so I'll split the difference. One of us knows a lot about brake fluid, and one of us doesn't. See if you can guess which-is-which.

You don't have to change brake fluid at all, but I figure when it rolls out of the bleeder screw looking like tobacco spit, this is a subtle hint for me to bleed the system 'til the clean, new fluid works its way down. That way, I keep the inside of my calipers and wheel cylinders from looking like the ones I (used to) work on from other people's cars. But I realize that there may have been 10 cars in the world whose brake fluid didn't get leprosy, and now I know that you've owned them all. (I'm chuckling, join in)

In fact, the really good news is that we don't have to change our oil either. I've worked on a Toyota Corolla that never had the oil changed in 65,000 miles. Some added (not much), but never changed. In her opinion, oil was not a normal maintenance item. And how can we argue with her results? Since her Toy still runs fine, I should, instead, feel silly for changing my oil every 3-to-5,000 miles.

As an interesting aside, I have a lawyer friend (can you say that?) who decided--stubbonrly--that he was NOT going to change the oil (or brake fluid) in his new Chevy pickup. And now, 7-years and 74,000 miles later, guess what? Still running.

Me, I change brake fluid when it bleeds out nasty looking at the caliper/wheel cylinder. If I never looked, I could assume it's clean and needs no attention. I know BF changing is unnecessary because it'll still stop with the old stuff in there.

I figure someone's going to give you the magic reason why you might show some concern for your brake fluid (water), but I'm thinking you may already know about it.

BTW: Porsche used to consider brake fluid change a normal maintenance item. Perhaps many others, don't know. Also, don't know if this is still the case. In fairness, you did say "In My Opinion." which is the reason I offered a few other opinions I've run into.

GeronimoPFudgemuffin - auto tech (and garage owner) for over 35 years

 

The Prius brake system is normally drive by wire, but there still is a master brake cylinder that the pedal is connected to. Normally the chambers are cut off from the rest of the hydraulic system, with the exception of one chamber connecting to a stroke simulator, which provides you with the viscus feel of ordinary brake systems.
If a problem develops where the hydraulic brakes cannot be electronically controlled, then valves would be opened in a specific order where you could statically control the front wheels but without any assist.
Normally high pressure is kept in an accumulator, which is released to the wheels via computer controlled valves as needed. Another set of valves releases pressure from the wheels, returning the fluid to the low pressure reservoir. Therefore, normally you could not feel the pedal operate and bottom out the wheel cylinders.
Although the hydraulic diagram doesn't show it this way, I'm told that the supply and return lines for each wheel merge to one line which is sent to the calipers themselves. So there is an opportunity where you could create a suction at the wheel caliper and draw in air if you aren't careful.

Also as a safety measure, there is a super capacitor power backup system for the brake system, so if 12V fails, the hydraulics can still operate normally for a short time.

I suppose one could devise a way to operate the solonoids manually, but it would take quite a bit of work to get to the control wires, especially at the actuator assembly. It would be an excellent idea to get the brake chapters of the repair manual before attempting any hydraulic work.
Except for regen, you'll probably be seeing many cars start working this way, if they haven't already for the purposes of ABS. VSC/ESC has to be able to operate the brakes without prompting by the driver.

 

<div class='quotetop'>QUOTE(GeronimoPFudgemuffin @ Nov 27 2006, 12:24 AM) [snapback]354341[/snapback]</div>

Geronimo, I am like seasalsa, I am not a mechanic nor do I play one on TV. I am just a user. I have owned cars since 1979, almost all used, and usually keep them for 8-10 years. I have NEVER had a shop recommend a BF flush out or replacement. Just bleeding if a wheel cylinder or master cylinder replaced.

I am sure that if BF changes were "routine maintenance", that would be listed in the owners manual. I mean c'mon, LOTS of people do that stuff religiously AT the dealers and what a way for them to make a buck.

So, you are a mechanic and you "feel" it is best to do these changes, based on your experience and training, but it is hardly a "generally accepted" thing. Being a mechanic "for 35 yrs" doesn't mean a lot because I know some "old time mechanics" that never changed their ways from the old carburator days (read oil changes every 3000 miles) simply not needed in modern cars.

This was not meant as a criticism, it was meant to give you a perspective from another point of view. I say more power to you all the way up until you start wasting resources (like my step dad who changed his oil every 1500 miles in a 2003 Chrysler.)

 

almost all CAA/AAA service people have access to a brake fluid tester for checking the moisture content of the fluid. Also a lot of good garages have the test available as well. If you have any doubt get your brake fluid checked. The CAA years ago had a test station set up in a mall parking lot offering a free brake fluid test. The results would make you sit up and take notice. About 45% of all vehicles tested had excess moisture in the fluid. I just wish Toyota made the brake system compatible with DOT5 fluid.

 

My Volvo dealer recommended it at 30K intervals, but since I DIY, I declined their offer. For a quart of brake fluid and 30 minutes of my time, I think it's worth the bucks and effort every 2 years, but I do live in the land of humidity. Does anyone doubt that brake fluid holds water? Have you never had to deal with a piston rusted into the caliper or a pitted master cylinder? Maybe it's just me, but since I started changing the brake fluid I seem to be spending a lot less on brakes, and I'll weigh even the environmental impact. A little more used brake fluid vs. say a master cylinder rebuild or a caliper swap seems like a win.

That said, I'm not even gonna try bleeding our Prius, for the reasons galaxee mentions (Thanks for posting the info) about the Prius brake system. I might change what fluid I can get to easily though. This car does challenge a lot of assumptions.

 

The cap box isn't supercaps, it's regular caps, but quite a few.
http://techno-fandom.org/~hobbit/pix/uyv3/999brake-caps2.jpg
.
_H*

 

One of my uncles, a farmer, taught me to flush out brake systems every two years. He had a lot less trouble with the brakes on the equipment that way. Once I got old enough to drive I did the same thing for all my vehicles, from old beaters to new vehicles.

Consider that if you live in a climate where road salt is used in winter, the brake bleeder screws will corrode. The disk brake slide pins will also corrode. If you ignore the system, when you finally do need something “simple†like front pads, when they attempt to compress the caliper the brake bleeder screw will be frozen.

They’ll keep trying and the bleeder screw will snap off. If they’re idiots, they’ll compress the caliper anyway and force the old grungy stuff up the system, possibly into the ABS actuator or master cylinder. If they’re not idiots, they’ll have to replace the caliper, which will cost a lot more than new pads.

If you every year or two crack open the bleeder screws and lube the caliper slide pins every year, there are very low odds of everything corroding up.

I have a 1984 Ford F-150 that I purchased new. Did the brake flush myself every two years. I finally needed new calipers last summer, because one of them started leaking at the piston boot. That year Ford truck used a huge single piston instead of two smaller pistons, so it’s easier to get a leak.

I knew from the start the Prius was an advanced car, especially with items like the brake stroke simulator. No way I’d even touch it, so I waited until last month to have my dealer do the flush for me.

I have a good dealer, the Prius tech even showed me the procedure on the screen and the involved THHT “dance†required to do the job. It took him an hour and they charged me for the container of brake fluid and one hour of labor. The tech even first siphoned out the old fluid and added the fresh fluid, so he wasn’t forcing old fluid through the system.

The tech even saved the fluid drained into a clear plastic container. It was pretty grungy looking. My brakes subjectively “feel†about the same, maybe a slightly firmer pedal, and it cost around $90 with tax.

 

Hmmmmm...rethinking my position. Maybe flushing out the BF on my 1997, since I am going to keep it for a long time, would be a good idea now. So, should I replace it with a synthetic that does not absorb water?????

 

<div class='quotetop'>QUOTE(Schmika @ Nov 29 2006, 11:42 PM) [snapback]355564[/snapback]</div>

I've heard if you go to the silicone stuff (DOT 5 or 6, I forget which) you need to completely flush the old fluid. If you just use something like DOT 3/4 Valvoline Synpower, it's compatible with what you have now (most likely, check your owners manual to be sure). I've not used the silicone stuff, but if I had another project car that was more a weekend racer, then I'd probably use that when I rebuilt the brakes. Someone mentioned the joys of rusted bleeder screws in another post, that's one thing you might want to watch out for. I'd forgotten about "rust never sleeps." Not a problem here in NC, so far, anyway.

Some folks will suggest that if you haven't changed it in ~10 years, then just leave it alone, but I'd suggest changing it now, if you find a problem then it was probably close to surfacing on its own anyway. Also, if you are not comfortable at all doing this yourself, then by all means do not hesitate to hire a pro. No brakes is no fun.

 

<div class='quotetop'>QUOTE(Beryl Octet @ Nov 30 2006, 02:07 AM) [snapback]355575[/snapback]</div>

Thanks, if I decide to flush, I would have a pro do it the right way, replace all that needs replaced...Silicone...that's what I couldn't remember. I am also thinking maybe go ahead and change the rear drums to rear discs. (It's a 1997 Sebring Conv...converting it to a show car)

 

it's been ~10 years so at this point it'd be perfectly reasonable to do so, schmika.

 

<div class='quotetop'>QUOTE(Schmika @ Nov 27 2006, 10:45 PM) [snapback]354678[/snapback]</div>

"Training?" Ahh, you flatter me! No training; just observation of dirty fluid and MUCH reading over the years... especially since 1996 when the Internet arrived in this household. My dad was a (renowned) GM mechanic since just after WWII, so any training he got (lots) would've surely rubbeb off on me. "Osmosis" would be the word.

And while I'm at it: May I apologize for my strident tone in the earlier post? I would still like to make the same point but, away from the keyboard awhile, I no longer feel comfortable trying to hammer your noggin with it.

Anyway, B/F change was on Porshe's scheduled maintenance, remembered because a lot of guys brought them to me (instead of the dealer) for all scheduled maintenance and I DARN WELL had to fill out, and check-off, the factory's list. I don't know for sure of any other manufacturers recommending same, but would bet a cup of coffee that all the VW/Porsche/Audi routines were very close... but that was "then" and this is "now." But, since I'm averaging 64-mpg, you won't have to come to SC to collect your free java. if I'm wrong, no problem since I CAN NOW AFFORD TO MAKE HOUSE CALLS! (the crowd roars)


NOTE:
SILICONE BRAKE FLUID - there's much reading to be done on this subject. I've changed-out a couple of vehicles, but they were motorcycles, so everything was within arm's reach. Unlike the guts of your ABS system.

WHAT I'VE READ:
1) "Some rubber brake parts are not compatible with DOT-5 silicone fluid" (not be confused with 5.5, which is totally different). I don't think I believe this. I'm not saying it's "wrong," but read on to find out where I think some of the confusion comes from

2) "DOT-5 should NOT be used in ABS systems" - I think it would do fine in an ABS system but, again, read on for reasons pro-&-con...

3) "DOT-5 will not absorb water, and therefore all moisture will migrate to the lowest point, stand in the caliper/wheel cylinder and cause corrosion" - True... well, sorta. DOT-5 doesn't "hold" water, and the moisture WILL migrate downward, but it appears to me that this is just what it does with regular brake fluid. The calipers are always filled with the "tobacco spit" Several bleeding strokes from the pedal usually clears up the fluid, so is this grunge & caliper corrosion with DOT-3/4 not due to the same exact thing they're warning me against with DOT-5?

4) DOT-5 aerates (gets bubbles) easier than DOT-3/4 - I'll take their word for it but note that it's never happened to me... yet.

ADDRESSING THE ABOVE POINTS:
1) DOT-5 incompatibility? Harley-Davidsons come with DOT-5 brake fluid and their calipers and master-cyls are sourced from the same place our brake parts come from. I say, "Liability."

2) Aeration (due to "hammering" action of ABS) in an ABS system? The very same system that is "incredibly well-sealed?" Unless heat makes DOT-5 separate and produce out-gases (and it might), how could this happen? And how much heat? 1500-degrees F? And if DOT-5 has just gotten hot enough to aerate, what new oxidized, carmelized compound would DOT-3 have already morphed into? (chuckling) And again I say, "Liability."

3) Non-absorbtion of water? Unless you're using DOT-5 so you'll NEVER AGAIN have to be bothered with looking at your brake fluid (not a good idea), this sounds to me like a GOOD thing. Make sure all the moisture in my braking system hangs around in my calipers and I'm a happy man! In fact, I'll even pay extra! Hang on to your hats: Sounds like "Liability" to me.

4) DOT-5 Aeration: Perhaps it does or else they wouldn't say it. But under what conditions does DOT-5 aerate where DOT-3/4 would have performed flawlessly? I say, "Lia..." well, you get the idea.

No manufacturer wants you to play around with the brake system they are liable for. There may be good reason DOT-5 is not fit for my Prius, but the facts are likely off-limits, obscured by the L*ABILITY issue. It's the same reason AVGas is still full of tetraethyl lead. Yes, I know it's called "100 Low-Lead," but it has orders of magnitude more lead in it than 1960's car gas. The "LL" is, I believe, a 'sell word." That spoonful of sugar that makes horse p**p taste better... I'm told.

I'm not putting DOT-5 in my Prius, and you probably shouldn't either. But my experience with it has been exemplary.

GeronimoPFudgemuffin

 

My dad used to be a mechanic for 20+ years, and I never recalled him mentioning changing the brake fluid.

However a mechanic at my church recommended changing ALL fluids somewhere around 70-90K.

Of all the cars I've owned, I've had high mileages and the cars were 4 years or older (some MUCH older), and had little trouble with most brake components. Nothing one wouldn't attribute to age anyway.

Coolants I have in the past not bothered changing and only had one car that had 240K spring a leak in the header just above the sparkplug causing it to short. I change coolants at manufacturer (car or fluid) recommendations.

So I suppose its all in one's decision.

 

<div class='quotetop'>QUOTE(hobbit @ Nov 28 2006, 01:58 AM) [snapback]354720[/snapback]</div>

The picture doesn't let you see the number of farads the capacitors have. Capacitors can be quite dense, yet their voltage can be low for large density capacitors. I've seen 1 farad capacitors that are quite small for the specification, but low voltage.

I was ridiculed by my professor for suggesting that 1 farad capacitors were of a reasonable size to be useful. I wished I had one to show him.

Hobbit is a brave man. I wished I lived near him.

 

<div class='quotetop'>QUOTE(hobbit @ Nov 24 2006, 08:40 PM) [snapback]353779[/snapback]</div>

After reading Hobbit's post I checked up on AutoEnginuity. It sounds as though it now has the ability to bleed Prius brakes, with an added Enhanced Toyota option:
http://www.autoenginuity.com/Toyota-All-Sy...t.html#commands
The cost from the manufacturer would be about $400. I think you can save $50 by buying the main tool from the manufacturer(?) on eBay.

Has anyone tried this with an AutoEnginuity? Does it work correctly?

 

<div class='quotetop'>QUOTE(DanMan32 @ Dec 1 2006, 01:15 PM) [snapback]356358[/snapback]</div>

Sort of off topic, but:

After they came out it was more than a year before I could force myself to stop saying "micro" before farad. Actually, I still have to stop and think. After all, I've been using terminology of microfarads many times longer than simply farads.

It depends what you mean by useful. I use ours to demonstrate RC time constant with #48 bulbs. They're rated at 5 volts, and have a physical size of about 1.5 cm by 4.5 cm diameter. That makes their energy density about (12.5 J)/(5.30 cm^3) or better than 2.3 joules per cubic cm, or 2.3 MJ per cubic m.

Dave M.

 

question since i'm a super cheap nice person and I DO know how to change my own brakes and machine my own crap and rotors, can't i just do the brake pad replacement and shoes replacement (my fronts are down to 25% ish) and then drive a couple miles to the dealership and get them to bleed it?

since making them replace the shit is so expensive (200 dollars just for ONE SIDE! wow) do you think i'd have a problem if i don't introduce air into the system while just changing pads/shoes?

 

Well, you're going to have to use something like a C-clamp to squish the pistons into the caliper. Otherwise the fresh new pads won't physically fit

IMHO you're getting royally screwed on the brake job. The Toyota dealers here charge the same whether a Corolla or a Prius. My dealership charged me $88 to actually FLUSH the brake fluid, including new brake fluid

 

You also have to be very careful, if you're going to work on the brakes. Remember the brake booster pump is always on. It can fire up anytime. Perhaps you'd be ok if you disconnected the 12V battery -ve terminal, but I'll let someone with a service manual comment on that. If it does fire up it -shouldn't- affect a pad change (unless you depress the brake pedal), but I suppose it -could-.

 

Well, how about if you already have the pads out, the boost pump for some reason decides to run, and the pistons shoot out the caliper?

Oops