This might assess the health of the pump, but not necessarily pending failure; the hydraulics should still work even with a flat accumulator albeit with a very heavy pedal. While this still would be a failure of the system, I wouldn't classify it in what I perceive to be the spirit of the survey - a sudden and complete loss of stopping power.
This might assess the health of the pump, but not necessarily pending failure; the hydraulics should still work even with a flat accumulator albeit with a very heavy pedal. While this still would be a failure of the system, I wouldn't classify it in what I perceive to be the spirit of the survey - a sudden and complete loss of stopping power.
Any suggestion? Hopefully there are other signs of impending doom. if my idea would in fact help assess the pump, which it may not, I'm no engineer, what might be signs of weakness in the other part?
I think pump run time does indeed assess the health of the pump system. I'm just not sure that a healthy pump is correlated 1:1 with a lack of sudden failure. If the MC piston were to fail, for example, the pedal would drop to the floor even with a healthy pump. The MC rebuilds that have been done here all had good pumps.
I voted no, but maybe should have voted yes. Depends on how you view it. I recently bought a '99 with 158k miles that had a gooshy brake pedal that quickly developed into a slow descent under constant pressure signaling a failed master cylinder. I bought the toyota rebuild kit and installed. Works much better now. If I had left it I would have experienced total brake failure at some point, but I feel worn master cylinders are different than complete, sudden brake failure. Now I'm worried about that...
I voted no, but maybe should have voted yes. Depends on how you view it. I recently bought a '99 with 158k miles that had a gooshy brake pedal that quickly developed into a slow descent under constant pressure signaling a failed master cylinder. I bought the toyota rebuild kit and installed. Works much better now. If I had left it I would have experienced total brake failure at some point, but I feel worn master cylinders are different than complete, sudden brake failure. Now I'm worried about that...
Maybe. Someone in the thread that started this topic mentioned the possibility that worn parts - such as a worn master cylinder, might put extra strain on the other parts - wearing them out more quickly. Makes some sense. I'm starting to think that there are likely multiple causes of failure, and other than re-engineering the whole system, we would benefit from 1) some benchmarks to help us know when a part is closer to failure, or 2) a rebuild/replacement schedule that reduces the chance of total failure.
I think pump run time does indeed assess the health of the pump system. I'm just not sure that a healthy pump is correlated 1:1 with a lack of sudden failure. If the MC piston were to fail, for example, the pedal would drop to the floor even with a healthy pump. The MC rebuilds that have been done here all had good pumps.
If run time would help assess a weakness, then we would be one step closer. The master cylinder seems more easily assessed - if flushing the lines don't help a soft pedal, then the MC is likely the reason, and a sign that attention is needed. In my mind - with my acknowledged limited knowledge! - it would seem that the an excessive run time could signal either a bad motor, or bad accumulator, or both. (Is my understanding of that correct???)
Might just be shade tree lore, but I've read that manually bleeding brakes is a common cause (yes cause) of MC failure. Why? Because when Mr. Piston travels 1" x 100,000 strokes the cylinder develops a wear ridge. Then when you bleed with the pedal and stroke the piston 1.5" the ridge abrades the piston ring and creates a leak path.
I read a thread on this after I bought the truck and was like ****!!!!!
This is not cool whatsoever.
I live in SoCal and would like to do a few trips up to the local mountains and such. Now I'm left to wonder if I take my wife and two kids up the mountain on the LX will we make it down safely.
In my neighborhood a few blocks away I have to drive down a steep hill and I'm always wondering "what if."
On that note. What would be standard "oh shiza!!!" procedure if brakes failed during a high rate of speed.
I read a thread on this after I bought the truck and was like ****!!!!!
This is not cool whatsoever.
I live in SoCal and would like to do a few trips up to the local mountains and such. Now I'm left to wonder if I take my wife and two kids up the mountain on the LX will we make it down safely.
In my neighborhood a few blocks away I have to drive down a steep hill and I'm always wondering "what if."
On that note. What would be standard "oh shiza!!!" procedure if brakes failed during a high rate of speed.
Thats what I would do... maybe look for any kind of uphill grade that is not "on road" that is "safe" enough to stop forward progress.. mind you thats if that is possible at all and would be if imminent impact of another vehicle was going to happen.
The fact that this discussion is happening and that IH8MUD exists with this many members/lurkers on top of other Toyota 100 series owners should be enough to get Toyota and NHTSA involved.
Or do we have to wait until some catastrophic episode occurs????
So, I just had the Brake light come on, followed by ABS, Trac etc. Brakes were gone on my way home, luckily i live at the top of a hill. Pulled into driveway, and brake fluid is pouring out from under chassis and the brake fluid level is down. Is this a symptom of the dreaded brake issue or maybe just a busted hose somewhere?
So, I just had the Brake light come on, followed by ABS, Trac etc. Brakes were gone on my way home, luckily i live at the top of a hill. Pulled into driveway, and brake fluid is pouring out from under chassis and the brake fluid level is down. Is this a symptom of the dreaded brake issue or maybe just a busted hose somewhere?
The fact that this discussion is happening and that IH8MUD exists with this many members/lurkers on top of other Toyota 100 owners should be enough to get Toyota and NHTSA involved.
Or do we have to wait until some catastrophic episode occurs????
Like most things with Corporations and Governments something bad has to happen in order for anything to get done (somebody dies and makes national news, etc)
Seems like a good PM would be a new pump/accumulator ($1200 parts) at 150k+ from what was mentioned.
I remember reading in the 100 FAQ the one "No Brakes" thread back when I had my 80 and was dumbfounded a brake system could basically have no real backup.
Indeed. The real issue seems to me to be -not the fact that some brake system failure can happen, that's bound to happen sooner or later to all mechanical devices- but rather that the system appears -from inference from the reports here- designed (or ill-designed?) in such a way that you may / will lose ALL the braking power at once. It seems inconceivable that there would not be an effective multiple-circuit system where you would have at least some of the braking capability left if one part of the system fails.
Having said that, before we start to panic, let's keep in mind that we are still basing some of our discussions here on anecdotal evidence with little empirical or hardware analysis to support the conclusions we are concerned about. Somebody knows enough about the system -or is willing to dig in- to shed some more substantiated light on all this? As in: is it a sure thing that if part X of the system fails, we lose ALL the braking power in a short period of time? I would be truly amazed if Toyota had not designed and implemented the system to avoid that possibility, that seems like such an obvious issue to have to design for.
Might just be shade tree lore, but I've read that manually bleeding brakes is a common cause (yes cause) of MC failure. Why? Because when Mr. Piston travels 1" x 100,000 strokes the cylinder develops a wear ridge. Then when you bleed with the pedal and stroke the piston 1.5" the ridge abrades the piston ring and creates a leak path.
In my neighborhood a few blocks away I have to drive down a steep hill and I'm always wondering "what if."
On that note. What would be standard "oh shiza!!!" procedure if brakes failed during a high rate of speed.
1. Try to keep calm/cool.
2. Downshift to 3rd/4th.
3. Downshift to lower gears and then
4 Apply emergency brake.
What else???? In what order????
This kinda sucks.
1. Keep your E-brake in good working condition (requires annual maintenance)
2. Downshift to 1st right away (the ECU will not allow changes that give "illegal" RPM, but shift down if the speed goes down)
3. In addition to using the E-brake - Use the brake pedal - and press hard - and f harder. When the booster has failed, you have only front brakes, and no power assist - requires hard work, by your right quadriceps, or both. The alarm will go off before the pressure is dangerously low, if the pump has stopped working. Just make sure you stop right away - and use the brakes only once or twice.
Might just be shade tree lore, but I've read that manually bleeding brakes is a common cause (yes cause) of MC failure. Why? Because when Mr. Piston travels 1" x 100,000 strokes the cylinder develops a wear ridge. Then when you bleed with the pedal and stroke the piston 1.5" the ridge abrades the piston ring and creates a leak path.
I can attest to truth in this. I've had it happen more than once on past vehicles. Bleed the brakes with lots of pumping and about a week later the master cylinder fails.
With that being said, I still do flush the system in the 100 yearly, and by pumping the pedal for the front brakes. It always scares me because I KNOW what is going on in there. I just hope the cylinder remains clean and smooth without a ridge to score up the plunger. I believe flushing regularly does help prevent that condition from developing.
BUT, If anyone knows of a way to bleed the front brakes without having to pump them PLEASE let me know.......
I'd be afraid to use any kind of pressure bleeder because of the plastic master cylinder tank and I tried vacuum bleeding with a Gast vacuum pump and it was ineffective. Fluid would not flow.
99 with 237k, accumulator pump was making an awful squeak but brakes were working fine. Replaced pump and did the master cylinder rebuild while it was apart. Combined with power stop drilled and slotted kit stops really well at 247k.
I can attest to truth in this. I've had it happen more than once on past vehicles. Bleed the brakes with lots of pumping and about a week later the master cylinder fails.
With that being said, I still do flush the system in the 100 yearly, and by pumping the pedal for the front brakes. It always scares me because I KNOW what is going on in there. I just hope the cylinder remains clean and smooth without a ridge to score up the plunger. I believe flushing regularly does help prevent that condition from developing.
BUT, If anyone knows of a way to bleed the front brakes without having to pump them PLEASE let me know.......
I'd be afraid to use any kind of pressure bleeder because of the plastic master cylinder tank and I tried vacuum bleeding with a Gast vacuum pump and it was ineffective. Fluid would not flow.
Only way to bleed without pumping the brakes is with the sst. I bought one on eBay awhile back, but have not been able to get the correct harness as they were out of production at the time. Just reminded me I need to check again. If I can get the harness was thinking I should turn the sst into a traveling loaner tool as it would just sit in my garage for months/years at a time.
