Poll on total brake failure in 100 series (1 Viewer)
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I did the master cylinder rebuild, and accumulator motor this past April (2019). Everything with that worked fine until today, including a 500+ mile road trip this past weekend. This morning, after start-up and warm-up, went to get in my LX to take the kids to school and I'm getting the screeching, the ABS light, and have a puddle on the ground under the master cylinder location. Looking in the engine bay, there's fluid on the back coil of brake line on the driver's side underneath the MC, but I'm having a hard time seeing where it's coming from. -15 Fahrenheit this AM. We've been getting an intermittent brake light when cold and the vehicle's cold that goes away when warmed up good. That's been happening for a while, but I didn't worry about it because it was consistently going away and only on when the vehicle and air temp were cold.
Thoughts?? I'm guessing that I've got a bad seal, loose flare nut, or cracked brake line somewhere. I've only looked for the source for a few minutes while shuffling the kids to another vehicle, and tracing the fluid up the line the highest I'm seeing at this point is a bracket on the inner fender. Haven't pulled out a mirror yet.
Thoughts?? I'm guessing that I've got a bad seal, loose flare nut, or cracked brake line somewhere. I've only looked for the source for a few minutes while shuffling the kids to another vehicle, and tracing the fluid up the line the highest I'm seeing at this point is a bracket on the inner fender. Haven't pulled out a mirror yet.
Some detail here would be great!
Like:
How long has screeching had been going on
Fluid level now, as seen after pump peddle 40 times key off.
History of brake fluid flushes.
A picture of your brake master.
Month and year the 99LC manufacture?
The alarm sounded earlier last night so I drove around the neighborhood and it went off. Brakes were working fine. About five miles later the alarm returned. Braking felt a bit soft. At that point it was only about two to three more miles before I really tested them and there was a near complete loss of braking ability.
I purchased last fall and unfortunately don’t have a history. It has been screeching since but the motor run time was very short (less than five seconds) so I figured it had more life in it. I will take some pictures this weekend and reply again with more info.
WOW two 99 in a row posted in same day^^ One in cold weather the other not!
Some additional detail here would be great!
Like:
Was this first time screeching heard
Have you been adding brake fluid over time to keep topped
History of brake fluid flushes.
A picture of your brake master or month and year the 99LC manufacture?
Not likely a flare nut, unless flare nut once loosened as yours was. More likely pump, accumulator has loosened, tube between master (reservoir) and accumulator assembly, grommets in bottom of reservoir, seal plate between Master and ABS unit (black box).
Getting alarms when cold is common in all Toyota's. I've been speaking with a master diagnostician at a Toyota Dealership. It's due to seal (rubber) wear & shrinkage with age. Then cold, shrinks them more. The system leaks pressure at various temp points as seal shrinks. This means fluid is leaking. The leak can be internal and or external. It can be so small not easily detectable. Very small leak/weep needs to be seen as it leaks or very shortly thereafter to find source. Sometimes signs of a leak can be found, like gunk build up on lower halve on anti squeal shims (caliper piston seal). A leak so bad it puddled, should be easy to find. But that is not normally the case in these cold weather alarms.
What I'm seeing is a higher instance in ones that have not been regularly flushed. But regardless of flush, age effects all rubber seals.
Here's where it get difficult. Which rubber seal do we replace and not all can be. First seal is in the reservoir cap and last is in caliper for piston.
Another question arises with seal issue cases. It's what fluid was used in the brake system. Where all DOT II, III or IV should be fine, are they? Toyota had a recall for 2005-2007 brake seal failure. This did not included 100 series. It only happen in brake system that had other than Toyota brake fluid added, causing a seal failure in the master. This should not have happen, and all brands equivalent brake fluid must be compatible. Fact it only happen in certain models, indicates the rubber used in those seal was a compatibility issue.
So naturally we'd think use Toyota brake fluid always. But the stuff Toyota sell in cans, is not the same as what comes from the factory. Brake fluid "was and may still be" made by same company, but formulated differently. Some EPA law, will not allow the factory formulated to be imported to USA. So does the Toyota cans have the proper seal modifiers we need? Who knows!
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Here’s what my reservoir looks like. Filled to the top with murky brake fluid.
Oh wow definitely a lack of maintenance. Your issue is probably a corrosive connections under the reservoir from leaking brake fluid.
Is there a remedy for that?
Good bet your brake accumulator motors commutator has dead spots. The FSM has a series of test for jumping brake booster motor with 12V battery. Once confirmed you'd need motor, brake control wire and wire screws and nuts.
Replacing motor will like give you back brakes. But the new motor & wire will turn pump at speeds it's not seen since system was new. This may then reveal more issues. Issue that age and lack of flushing brake fluid causes.
Unfortunately we see to many of these offer filled. If the brake fluid did get into wire's boots. The wires well be corroded. You can easily peel back the boot exposing the wires and see.
If you go back and read through this thread you'll see more about this, diagrams and pictures.
Here's picture of wires at base of ABS unit (black box on side of brake master)
Maybe best to just replace entire master cylinder assembly and start treating it right.
That is hands down the best.
that would be best. No question. I'm in favor of replacing the motor/pump/accumulator section and the master cylinder piston at (maybe) around 150K miles. Saves over half the cost of parts vs the full master assembly.
about $820 (which is cheaper than when I bought it a few years ago) for the 99:
- SKU:47070-60010
- Other Names:Motor & Pump, Pump Assembly, Actuator Pump, Pump Assembly Brake Boo
- Description:
LAND CRUISER; ACCUMULATOR & PUMP ASSY.
Just replacing booster motor or booster assembly (motor, wire, pump & accumulator).
1) Issue
Issue comes up with with replacing just the booster side of master. Issue seems to be most prevalent in brake systems not regular flushed. Issues we're see, is the motor keeps running or runs too long and may be accompanied by screeching. This is more prevalent when cold (below freezing).
One reason for this, is age of rubber seals, combined with damage from old brake fluid (moisture in fluid) on seals and the surface they seal. Then when cold, the rubber shrink. There are at least two seals in the master we can not get from Toyota. One is a large seal plate between master and ABS. The others is buried deep in master cylinder, behind the plunger.
The seal behind the plunger we may be able to find a replacement, but we can't get to. This one "may" be one of the cause of the screeching. This one may yield a pressure leak, with no external fluid leak. So very difficult to detect.
Beyond the master we can replace seals. Those are the caliper piston seals. But in a poorly maintained system, the piston will be damage from moisture in brake fluid. So then we need the caliper kit & pistons at minimum.
2) Issue
The ABS units (black box on side of master) themselves do sometimes fail. The one I saw fail, had a corroded brake control wire. Seeing only one failure of ABS unit, with a brake control wire that has higher resistance due to corrosion, is not enough to say we've a correlation. But it is something to consider.
3) Observation
Replacing even just a corroded brake wire, can increase the speed of old booster motor. The increase speed, may increase brake fluid pressure in the system. The added pressure may reveal weak seals of old system. Weak seal(s) may prevent system from reaching predetermined pressure to signal motor to shut down.
Motor running to long will wear out prematurely. IIRC 5 minutes run time or longer, and it will set of a DTC. FSM limits our run time test of booster motor to 2 minutes, to avoid damaging it. Dammed if you do dammed if you don't.
Conclusion:
Whether or not Toyota bottles of brake fluid is better for our seals or just any equivalent brake fluid works just as well, I can't say.
I can say:
1) Flushing the system to keep fresh fluid in it, is best practice.
2) Keeping good rubber bleeder caps on bleeders at all times, is best. This protects bleeders and their seats in the calipers.
3) Never over fill the reservoir. Overfilling is likely cause of wire corrosion, which damage motor and possibly ABS unit.
4) If brake control wire is corridor, replace it.
1) Issue
Issue comes up with with replacing just the booster side of master. Issue seems to be most prevalent in brake systems not regular flushed. Issues we're see, is the motor keeps running or runs too long and may be accompanied by screeching. This is more prevalent when cold (below freezing).
One reason for this, is age of rubber seals, combined with damage from old brake fluid (moisture in fluid) on seals and the surface they seal. Then when cold, the rubber shrink. There are at least two seals in the master we can not get from Toyota. One is a large seal plate between master and ABS. The others is buried deep in master cylinder, behind the plunger.
The seal behind the plunger we may be able to find a replacement, but we can't get to. This one "may" be one of the cause of the screeching. This one may yield a pressure leak, with no external fluid leak. So very difficult to detect.
Beyond the master we can replace seals. Those are the caliper piston seals. But in a poorly maintained system, the piston will be damage from moisture in brake fluid. So then we need the caliper kit & pistons at minimum.
2) Issue
The ABS units (black box on side of master) themselves do sometimes fail. The one I saw fail, had a corroded brake control wire. Seeing only one failure of ABS unit, with a brake control wire that has higher resistance due to corrosion, is not enough to say we've a correlation. But it is something to consider.
3) Observation
Replacing even just a corroded brake wire, can increase the speed of old booster motor. The increase speed, may increase brake fluid pressure in the system. The added pressure may reveal weak seals of old system. Weak seal(s) may prevent system from reaching predetermined pressure to signal motor to shut down.
Motor running to long will wear out prematurely. IIRC 5 minutes run time or longer, and it will set of a DTC. FSM limits our run time test of booster motor to 2 minutes, to avoid damaging it. Dammed if you do dammed if you don't.
Conclusion:
Whether or not Toyota bottles of brake fluid is better for our seals or just any equivalent brake fluid works just as well, I can't say.
I can say:
1) Flushing the system to keep fresh fluid in it, is best practice.
2) Keeping good rubber bleeder caps on bleeders at all times, is best. This protects bleeders and their seats in the calipers.
3) Never over fill the reservoir. Overfilling is likely cause of wire corrosion, which damage motor and possibly ABS unit.
4) If brake control wire is corridor, replace it.
^^^ Thanks for the thorough analysis! I will keep an eye out on the possible problem spots. Hopefully my somewhat regular brake flushes have saved me from the worst, and my halfxxxed prevention will keep me stopping for the next 150K miles. I suppose if I'm still driving it then I might want to replace the whole assembly. I like stopping more than I like going. (The unexpected thrill of a road way free-fall is something I want to avoid!)
I do appreciate your following and analysis of this topic. I don't know of anyone else that could provide us with such carefully thought out comments!
Gil
Ventura, CA
I do appreciate your following and analysis of this topic. I don't know of anyone else that could provide us with such carefully thought out comments!
Gil
Ventura, CA
Your welcome.
I'm all for working step by step Part by part and repeatedly pulling master if need-be. But I've really come to understand, why Dealership will not do this. One reason is time involved and inconvenience to client.
I'm all for working step by step Part by part and repeatedly pulling master if need-be. But I've really come to understand, why Dealership will not do this. One reason is time involved and inconvenience to client.
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Dug around and found that the leak was definitely coming from the body of the MC. Looks like either the (what I'm assuming is) o-ring around the plastic tube to the accumulator, OR the two holes that look like they've got bb's in them below that. The fluid was leaking onto the rubber cover on the accumulator motor wires, and then down to the brake line below that (I'll be completely degreasing the wires before install, but it doesn't look like any actually got in the boot). SOOOOO. . ., out the MC came and it's now on my bench. I've ordered a new one. That hurt.
Looking at that tube, I see it's pinned in, and it's only a one-sided hole so that the pin can't ever be removed and the tube seal serviced. Really poor design choices in my opinion. And those same poor choices abound in this assembly. Like why did they chose an electric booster instead of the trusted vacuum system? Ugh.
Details: 1/99 build date, the screeching I heard was the ABS alarm inside the cabin and the only other time I heard it was when the accumulator motor went out in April, I've NOT been topping up as I saw no prior signs of leakage, I've had this one only a bit over a year so I don't know flush history (that being said, the fluid was essentially black when I bled it in April with the booster motor change and MC rebuild, and this time it's still a pretty nice dark color, so I'm guessing it was never). I've got some pics of the MC on my phone and I can try to get them on here. I used DOT III when I did the job in April
If anyone has any surefire ideas to get my potential leak areas resealed, I'm all ears. I wouldn't mind returning a $1300 part. But if they aren't surefire, I'm not going to trust my wife and kids to the old MC.
Build date on mine was 09/98. Replaced the entire assembly and have the old one sitting in my garage. If anyone is interested in doing a rebuild with it let me know.
I promise I tried to look through this thread a bit, I'm not sure how to describe it to search for it but didn't see this exact scenario...I have a 99' (don't know the build date) but after two different days on a trail I felt squishier brake normal. I turn the car off and wait a bit and the stiffness kinda comes back. However on the way back home I heard a very static-y whining sound from behind the dash and the ABS and BRAKE light flickered for 2-3 seconds and then stopped, then about 5 minutes later it did the same thing, then I never heard or saw the lights again. I do not think however it was the alarm, which is heard someone on here record on their 2001, this was not intermittent beeping but a strange whining static noise. Anyways I assumed the sound was the booster or the master cylinder. I did the test when I got home of pumping the brakes 40 times, and then turn the car on but not starting the motor. I could hear the brake motor working and timed it on my phone to 40 seconds on the dot. I've heard 30-40 seconds is typical, it was not particularly loud at all. I have not had this happen now for two weeks.
Mileage on Car 504,XXX
Brake fluid flush at 495,XXX, before that kinda unknown, also put on SS brake lines in the front at the time, and turned down rotor and put some cheap pads in rear
BMC could be original, don't know
I've not had to add any brake fluid, no air bubbles or anything like that.
Anyways, am I most likely a candidate for a MC/Booster rebuild? Or new unit (hope not)? Or might this simply be air in the lines and I need to bleed lines? Is this a ticking time bomb I should take action on?
Mileage on Car 504,XXX
Brake fluid flush at 495,XXX, before that kinda unknown, also put on SS brake lines in the front at the time, and turned down rotor and put some cheap pads in rear
BMC could be original, don't know
I've not had to add any brake fluid, no air bubbles or anything like that.
Anyways, am I most likely a candidate for a MC/Booster rebuild? Or new unit (hope not)? Or might this simply be air in the lines and I need to bleed lines? Is this a ticking time bomb I should take action on?
