Will do, thanks!
Poll on total brake failure in 100 series (7 Viewers)
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98 LC with 165k miles
Booster pump and accumulator changed 3 years ago. Strong and consistent braking but experienced the sams as above recently. Brake fluid and correct bleed by dealer 6m ago.
All was fine and pulled into service station to check tire pressures. When I restarted after perhaps 5 min stop, pedal went soft and towards the floor with little braking assistance. Note that i immediately started moving after start up, didn’t leave any time for booster pump to run. No warning lights, no alarm, no apparent leak. Resumed very cautiously and normal braking resumed. Currently car at airport parking and with covid it may stay there for a couple of months.
to Tmcruiser: can you please report what you find out as this really looks similar. What valve are you referring to ?
thanks
Booster pump and accumulator changed 3 years ago. Strong and consistent braking but experienced the sams as above recently. Brake fluid and correct bleed by dealer 6m ago.
All was fine and pulled into service station to check tire pressures. When I restarted after perhaps 5 min stop, pedal went soft and towards the floor with little braking assistance. Note that i immediately started moving after start up, didn’t leave any time for booster pump to run. No warning lights, no alarm, no apparent leak. Resumed very cautiously and normal braking resumed. Currently car at airport parking and with covid it may stay there for a couple of months.
to Tmcruiser: can you please report what you find out as this really looks similar. What valve are you referring to ?
thanks
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Looking for a 100 series for a while - and while I have not read this entire thread it is of course troubling to read. However, knowing human nature we are more likely to respond to something we have an interest in or have experienced than something we have not. So the 20% failure rate of responses here is likely skewed upwards and it is highly unlikely anywhere near 20% of all 100 series sold have had total brake failures.
I am not sure this can be answered - but do 100 series suffer from total brake failure any more often than other similar 15-20 year old vehicles?
I am not sure this can be answered - but do 100 series suffer from total brake failure any more often than other similar 15-20 year old vehicles?
if you're talking brake failure in terms of caliper failure, brake hose failure, or other mechanical elements of the system then no.
The 100 is unique that it has this extra element of an electric brake booster which comes with it's own unique maintenance and operation requirements - many of which it seems that owners and shops don't know how to handle. For example, my reputable Toyota mechanic overfilled the reservoir and didn't follow the procedure printed on the unit.
A lot of the people I see post in this thread about total brake failure with no warning had a failure somewhere else in the system (like a rusted brake line). This could happen in any car and has nothing to do with the MC or booster.
The MC/booster can fail as mine did, but should provide ample warning. I would assume it would fail at the same rate of any other Toyota/Lexus that came with the same setup - 4runner, Tundra, Prius, some Tacomas, GX470, GX460 etc.
Voted no. 2001 LX w/ 106k. Adjusted my parking brake just in case!
OK, just to follow up, got my unit from Andy Le installed and driven the truck back and forth to work maybe a week and a half, all is well, he returned my core charge, and he's a good guy,
We had a bit of mishap with one unit he sent, so things got delayed a bit. Not sure why, but some seal blew between the master cylinder and the ABS control box on the side. When I started the bleeding process, a bunch of brake fluid came out through the box on the master cylinder and ran down onto the ground, and there was no brake pressure at all. Andy was quite helpful in sorting it out, and then just sent me another unit and he took care of the extra shipping costs. I should've known there was an issue with that unit as I noticed a bunch of brake fluid in the wiring boot when I opened it. Maybe it got damaged in shipping, who knows.
With the second unit, it took me a while to get it working properly, not sure if there's a specific bleeding process I missed. I tried bleeding all 4 wheels like instructed in the DIY master cylinder rebuild thread, and that was not enough to get it to quit beeping, and the pump would only run for 5 seconds at a time. I pumped the brakes a bunch and eventually let it idle for like 5 to 10 minutes while I fired up the ancient laptop with techstream to find ABS codes, and by that point the LC had sorted itself and no more beeping and no ABS codes. Brakes worked great, took it up the driveway and activated ABS, and re-bled all 4 wheels.
With 2001LC's standard of 40 pumps to no pressure and 40 seconds motor run time, it may have been close or a little off from that at first, but seemed to improve after a couple days of use. Last time I checked brake fluid it was well over 40 pumps with still pressure, even though it may have been 38 or so pumps until no pressure right after I had installed it. Maybe it just needed some priming and use.
Well I sent both units back, and he returned my core charge and the cost of shipping the second one back.
So anyways, quite happy to have a refresh of the whole booster assembly, and recommend Andy Le. It looks like there are several rebuilders on ebay, but if you see one listed as in Rancho Cordova, thats probably him. If you just contact him through FB it may be easier, though.
The way to top reservoir is spelled out on the reservoir. "IG key off pump pedal 40 times or more. Than top. DO NOT OVERFILL"
After bleeding the FSM calls for doing this same procedure. Then recommends timing booster motor run time. Spec. is 30 to 40 seconds. FSM then states, if motor runs over 40 seconds, rebleed the system. Most times that I go over 40 seconds, I find a bleeder weeping. Especially when bleeder caps have been off for extended time (months or years) and bleeder has rusted.
What I've notice during the brake pedal pump procedure. The more pumps until brake pedal pressure loss (resistance/pressure drops off). The weaker the accumulator. With a new booster assembly, I see 22 to 25 pumps, until pedal pressure drops off.
These rebuilt brake master assembly w/booster. Very often have weak accumulator, pump and motor (booster assembly). If you put on a new booster assembly. Very often, you'll end up with the squeal and associated bubbles. Weak booster take more pumps to evacuate.
After bleeding the FSM calls for doing this same procedure. Then recommends timing booster motor run time. Spec. is 30 to 40 seconds. FSM then states, if motor runs over 40 seconds, rebleed the system. Most times that I go over 40 seconds, I find a bleeder weeping. Especially when bleeder caps have been off for extended time (months or years) and bleeder has rusted.
What I've notice during the brake pedal pump procedure. The more pumps until brake pedal pressure loss (resistance/pressure drops off). The weaker the accumulator. With a new booster assembly, I see 22 to 25 pumps, until pedal pressure drops off.
These rebuilt brake master assembly w/booster. Very often have weak accumulator, pump and motor (booster assembly). If you put on a new booster assembly. Very often, you'll end up with the squeal and associated bubbles. Weak booster take more pumps to evacuate.
Yeah, I know the top off procedure man.
It only took over 40 pumps the other day after i had let it it sit for a day or two with the engine off, so it wasn’t really an ideal test, hah. I was just checking for fluid loss at the time. But just a few posts ago you said that that 37 pumps was bad, now you say even less than that is good, plus 40+ is bad too, and I don’t know if I really trust any of these numbers exactly because we can all press the pedal with a different amount of force, speed, and stroke.
It only took over 40 pumps the other day after i had let it it sit for a day or two with the engine off, so it wasn’t really an ideal test, hah. I was just checking for fluid loss at the time. But just a few posts ago you said that that 37 pumps was bad, now you say even less than that is good, plus 40+ is bad too, and I don’t know if I really trust any of these numbers exactly because we can all press the pedal with a different amount of force, speed, and stroke.
Also, Andy has said that he pressure tests the accumulators that he sends out. I forget the spec, and FB is hard to search, but if it doesn’t hold the proper pressure he pitches it because they can’t be repaired. The guy knows the whole system inside and out and I trust his knowledge here.
You seem to be taking my post personally. "MAN!". PLZ Don't!
I've not meant to "dis" you or your supplier.
You implied my "standard" test "With 2001LC's standard of 40 pumps to no pressure and 40 seconds motor run time" This is not some test I came up with, but one in the FSM. The 40 pumps are minimum recommended to evacuate accumulator of brake fluid. The 40 second maximum time. Not standards of mine!
Maybe this will clear up my thinking for all, with the issue of "number pumps of pedal"
These are observation I've made over years inspecting many 100 series:
After cycling booster assembly at least once, at and OAT of ~72F. Cycling is; pump pedal at least 40 time w/IG OFF and than run booster pump until it stops. Than repeat. Note pedal pumps and times. The less pumps until evacuation, the better condition of the accumulator IMHO. This is "ONLY"an a "fast field test" for indication of health of booster assembly. i.e accumulators remaining gas charge.
What I've notice during the brake pedal pump procedure. The more pumps until brake pedal pressure loss (resistance/pressure drops off). The weaker the accumulator. With a new booster assembly, I see 22 to 25 pumps, until pedal pressure drops off. In older system when I see 35, 36, 37, 38, 39, 40 pumps or even more. I find, they have weak boosters assemblies. Additionally temperature can play a roll also. As rubber seal expand and contract with temperature. But that has more to do with master and calipers seals. This (how many pump) is not a test in the FSM. But and indication I use during my inspections. IMHO: More pump is indications of weak accumulator.
When I take these old master assembles. Especially those showing staining in the reservoir. Bring pressure back to near or at factory like new condition. Then these master are failing about 50% of the time.
By "Master Fail" I'm talking about the so called screaming banshee. This is screeching sound with bubbles come up front of reservoir. Currently there is one thing we can do with these "Master fail" Replace the master. Currently I know of no one, that can restore a master. Replacing the master plunger is not the same. Anyone can do that.
Most brake master rebuilders, I assume know this. If they bring pressure back up to at or too near factory new. The master will fail 50% of the time. So they mark every part of master with anti tamper paint/seal, and shipping with weaker booster assemblies. Touch any part, warranty void.
^2001LC knows what he's talking about.
This Andy Lee guy on FB, sure he's got a good rep for rebuilding 100 series masters but there are seals internally that can't be replaced. The accumulator is just one part.
Sure, anyone can replacing the mc plunger, and rebuild the booster motor, but there can only be so much done. Once these 100 series MCs are too far gone, the only solution is to replace them with a new unit. The seals which are non-replaceable are 20+ years old now, with grit stuck on them, and shrink when it gets cold.
This Andy Lee guy on FB, sure he's got a good rep for rebuilding 100 series masters but there are seals internally that can't be replaced. The accumulator is just one part.
Sure, anyone can replacing the mc plunger, and rebuild the booster motor, but there can only be so much done. Once these 100 series MCs are too far gone, the only solution is to replace them with a new unit. The seals which are non-replaceable are 20+ years old now, with grit stuck on them, and shrink when it gets cold.
Hey Andy Lee,
Thank you for stepping-up and validating my findings.
Please give me your thoughts on:
It's my belief, there is a seal in the end of these brake masters, forward of the master plunger. It is this seal, that we can not get to. That as pressure comes up between accumulator and master. This seal leaks under high pressure. Then we hear the screeching sound and see the bubbles in the reservoir. Do you agree?
Have you been able to get to, the forward seal. Possibly by removing the retaining ring and plate set in at front (front of vehicle) of master?
Sure age is in the equations. But bad fluid condition and possibly brand/type of brake fluid is main cause of failure. That old fluid, which has high moisture content, which-in-turn builds up organics (as I call them). Damages that forward seal in master. Then it won't hold higher pressure, that is near factory new levels?
That a sign a master will not hold these pressures, a system once had (day it came from the factory). Is very dark fluid and or fluid quickly turns dark after a very thorough fluid flush?
That all seals, all the way to the caliper pistons and pistons themselfs get damaged from improper PM?
Not a 100-series, but same module: my 1998 Lexus GS400 developed the banshee screech somewhat suddenly. I heard it twice for a few seconds several weeks apart and didn’t know what it was, until last week when it started screaming constantly. It only lasted about five minutes before it stopped and the warning lights and buzzer went crazy. Luckily I was in my neighborhood and just limped home in second gear. Funny enough, it came back to life when I had to panic stop for some teenage idiot that pulled out right in front of me.
I got a low-ish mileage unit from an SC430 from an eBay seller. Just gotta swap one sensor and it’ll bolt right up, and supposedly give me a performance boost thanks to revised internals.
Anyway, the important takeaway is that a failure should give some warning, but once the warning signs appear, fix it immediately.
I got a low-ish mileage unit from an SC430 from an eBay seller. Just gotta swap one sensor and it’ll bolt right up, and supposedly give me a performance boost thanks to revised internals.
Anyway, the important takeaway is that a failure should give some warning, but once the warning signs appear, fix it immediately.
Well I don't have a 100 series yet. Just doing research. That's why I can't vote.600 views but only 80 votes. What's with that? Either a few 100 people with a morbid fascination for the issue coming back over and over again, hoping to see the failure rate go down, or the damn 80 guys enjoying our poor 100s getting hammered by brake failures....?
Vote guys, vote! This can't be true....
I'm in a tough spot here. I'm in CA for a next few weeks and plan on driving back to MN in the 100. I was doing a few routine checks and decided to do the ol' pump the pedal until it goes soft and time how long the pump runs. I was getting a consistent 32-34 sec. I've had no issues with my braking performance and I've bled them within the last year. While I was there I noticed an odd seepage of what appears to be brake fluid. It is a really slow seep and I think I caught it early since none has actually dripped onto the driver fender. I've never had to add more fluid to the system, its a little above the minimum level after the pump runs. I checked the electrical connections which are corrosion free. It's my understanding that you can't really replace the seals in the MC, rather, I'd probably have to buy the $2300 part. What would you guys do? Also, does anyone have any LC shop recommendations in the LA area that would have experience with these brake systems?
EDIT: I should also mention this is a southern truck with no rust so it's unlikely to be corrosion related.
EDIT #2: The more I think about this the more confused I get....I don't even understand how it could be leaking from there, the MC is on the other side of the module and it doesn't appear to be leaking. Seems like the seep is coming from the plastic cover.
EDIT: I should also mention this is a southern truck with no rust so it's unlikely to be corrosion related.
EDIT #2: The more I think about this the more confused I get....I don't even understand how it could be leaking from there, the MC is on the other side of the module and it doesn't appear to be leaking. Seems like the seep is coming from the plastic cover.
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Clean and see if returns.
Was level at, above or below max line after pumping pedal 40 time?
Most leaks are actually reservoir overfilled.
Second leak is at very bottom from pump. If air vent at bottom of pump to motor gets plugged, it can cause a leak. By motor spinning, sucking fluid from pump.
Not to common would be the grommet at bottom of reservoir.
Not so common is hard line and/or flare nut. Unless been off!
If leak between ABS (black box) and master at seal plate (not common). The seal plate is not sold. But a recycled may due. There is 6 bolt hold the components together. They're always tight and leak here is rare.
If face plate of ABS, you'll need new master or recycled ABS unit. Internal leak here is so rare I've never seen, and not serviceable
Regardless of where from. As long as motor runs on demanded when pressure drops, and fluid hold in system. Pressure builds in system and so we have brake assist.
Was level at, above or below max line after pumping pedal 40 time?
Most leaks are actually reservoir overfilled.
Second leak is at very bottom from pump. If air vent at bottom of pump to motor gets plugged, it can cause a leak. By motor spinning, sucking fluid from pump.
Not to common would be the grommet at bottom of reservoir.
Not so common is hard line and/or flare nut. Unless been off!
If leak between ABS (black box) and master at seal plate (not common). The seal plate is not sold. But a recycled may due. There is 6 bolt hold the components together. They're always tight and leak here is rare.
If face plate of ABS, you'll need new master or recycled ABS unit. Internal leak here is so rare I've never seen, and not serviceable
Regardless of where from. As long as motor runs on demanded when pressure drops, and fluid hold in system. Pressure builds in system and so we have brake assist.
Good questions. It was at the maximum mark after pumping pedal. I've never touched the MC or flare nuts. I put my hand under and felt around for liquid and couldn't feel/see anything on the booster motor. I will clean and observe. If I had to guess its coming from the ABS seal plate, which is unfortunate. I only have basic hand tools here so I probably wouldn't want to attempt a full MC change in CA. May have to pay dealer prices if it gets worse.
There are important instructions on top of the reservoir that the level should be checked only after "emptying" the MC by doing the 40 pumps.
What 2001LC was saying is that most "fluid leak" issues you see are from inexperienced mechanics setting it to the max level incorrectly. Then when the system empties itself it goes way above the max lines and leaks out of the cap, dripping down the side and ending up who knows where.
If you do the 40 pumps, pedal goes to the floor, and the fluid line is above the max line then use a clean turkey baster or something similar to pull some out.
Yes, I understand what he was saying about fluid level. The level is properly set on the reservoir per the instructions on the res. I cleaned the fluid that had leaked in the picture and can tell that its still slowly weeping. Still isn't accumulating enough fluid to drip, but it appears that the ABS seal plate (between black box and MC) is sweating brake fluid.
It's difficult to verify my suspicions without removing the MC itself, which I don't wanna do this far from home. Maybe on my way back I can stop in Denver and get a proper diagnosis...
It's difficult to verify my suspicions without removing the MC itself, which I don't wanna do this far from home. Maybe on my way back I can stop in Denver and get a proper diagnosis...
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I'd just drive until back home.Yes, I understand what he was saying about fluid level. The level is properly set on the reservoir per the instructions on the res. I cleaned the fluid that had leaked in the picture and can tell that its still slowly weeping. Still isn't accumulating enough fluid to drip, but it appears that the ABS seal plate (between black box and MC) is sweating brake fluid.
It's difficult to verify my suspicions without removing the MC itself, which I don't wanna do this far from home. Maybe on my way back I can stop in Denver and get a proper diagnosis...
I'd be alert and keep eye on fluid level.
I'd make sure I can hear when booster motor running (no radio). If runs longer than 2 minutes, I'd pull over and check level in reservoir.
I'm very good with engine braking and not tail gating. On ice and snow I learned, to give extra stopping distance. Would do same here.
If you're concerned with loss of brakes, have towed to Dealership now.
PM, if you like to stop by for me to take a look.
