Poll on total brake failure in 100 series

[Snow Wagon]

Hello Forum,
2003 LX470 w/ 135k miles.

Kid on a scooter scooted out in front of me.
Slammed on the brakes.
SUV stopped just fine.
Kid is fine.
Most likely crapped his pants.
Pretty confident he'll remember the incident and look both ways before scooting across the road.

Less than a mile later, approached a stop light going around 25 MPH, went to hit the brakes for the 1st time after the emergency stop, and the pedal went more or less to the floor.
Used the emergency brake and pulled off to the side of the road.
No dash lights.

Popped hood and found brake fluid slowly leaking from the bottom of the brake booster / master cylinder assembly.
No dash lights appeared until the brake fluid level was officially "low" from the slow leak.
Only DTC is C1202 (Low Brake Fluid).

I'm guessing I've blown a seal out of the assembly.
Anyone encounter this before?

I'm pretty confident that the rebuild kit (04493-60330) will not help me, correct?
I believe it just includes the plunger and seals and the assembly would not leak if one of those seals failed (it would leak internally, not externally...).

I read about Andy Le doing rebuilds and I've reached out to him.

Any thoughts are greatly appreciated.

Thank you.
Tom

 

[wngrog]

Hello Forum,
2003 LX470 w/ 135k miles.

Kid on a scooter scooted out in front of me.
Slammed on the brakes.
SUV stopped just fine.
Kid is fine.
Most likely crapped his pants.
Pretty confident he'll remember the incident and look both ways before scooting across the road.

Less than a mile later, approached a stop light going around 25 MPH, went to hit the brakes for the 1st time after the emergency stop, and the pedal went more or less to the floor.
Used the emergency brake and pulled off to the side of the road.
No dash lights.

Popped hood and found brake fluid slowly leaking from the bottom of the brake booster / master cylinder assembly.
No dash lights appeared until the brake fluid level was officially "low" from the slow leak.
Only DTC is C1202 (Low Brake Fluid).

I'm guessing I've blown a seal out of the assembly.
Anyone encounter this before?

I'm pretty confident that the rebuild kit (04493-60330) will not help me, correct?
I believe it just includes the plunger and seals and the assembly would not leak if one of those seals failed (it would leak internally, not externally...).

I read about Andy Le doing rebuilds and I've reached out to him.

Any thoughts are greatly appreciated.

Thank you.
Tom

They pricing is so good on the new units you need to just buy new.

 

[OwnerCS]

No but proactively replaced the booster and masster cylinder at 320,000 miles.

 

[OwnerCS]

They pricing is so good on the new units you need to just buy new.

There is a 20% off + Free Shipping (over $75) sale going on right now.

 

[dnp]

They pricing is so good on the new units you need to just buy new.

^^THIS^^ They're not cheap, but considering the price of a whole "contraption" has come down from around $3,000 to about $1,500, the price for that peace of mind IS cheap.

 

[2001LC]

Hello Forum,
2003 LX470 w/ 135k miles.

Kid on a scooter scooted out in front of me.
Slammed on the brakes.
SUV stopped just fine.
Kid is fine.
Most likely crapped his pants.
Pretty confident he'll remember the incident and look both ways before scooting across the road.

Less than a mile later, approached a stop light going around 25 MPH, went to hit the brakes for the 1st time after the emergency stop, and the pedal went more or less to the floor.
Used the emergency brake and pulled off to the side of the road.
No dash lights.

Have you ever heard, the brake low pressure alarm?

We can test/activate the alarm, to see if working. By: IG key on, pump brake pedal rapidly. In a new booster ASSY w/ brake master, takes ~30 pumps to set off alarm. In old weak system, ~10 pumps.

Popped hood and found brake fluid slowly leaking from the bottom of the brake booster / master cylinder assembly.
No dash lights appeared until the brake fluid level was officially "low" from the slow leak.
Only DTC is C1202 (Low Brake Fluid).

If fluid gets to low, we can get air in to master and brake lines. Pedal will go low.

Some have seen leaks form one or more of the grommets, at bottom of reservoir. I have not seen these leak.

I have seen leaks form:
ABS unit (black box on side of master). Typically set off get brake alarm.
Weep hole at bottom of pump. This happens if booster motor breather gets clogged.. Motor will then, suck fluid from pump.

If booster motor is working. Test:
IG key OFF. Pump brake pedal 40 times. See level in reservoir raise. Turn IG key ON. Hear brake booster motor run. Time how long it runs. Battery at 12.5V 30 to 40 seconds.

I'm guessing I've blown a seal out of the assembly.
Anyone encounter this before?

I'm pretty confident that the rebuild kit (04493-60330) will not help me, correct?
I believe it just includes the plunger and seals and the assembly would not leak if one of those seals failed (it would leak internally, not externally...).

If leaking at plunger (seal kit). Leak would be in foot well. Not in engine bay.

I read about Andy Le doing rebuilds and I've reached out to him.

Any thoughts are greatly appreciated.

Thank you.
Tom

Remain master. Are a bad idea.

Thread 'Brake Master ...... Overdue write-up.'

Nov 1, 2020

First and foremost: Brakes should only be worked by those, with high level of mechanical abilities and experienced with brake systems.

With the age of all 100 series today, in our aging fleet. Any issue, with brake master assembly. IMHO, best and safest course of action. Have the whole brake master assembly, replaced with new. If you have to ask question, on "how to", your not qualified to work on the master.

My hope is below link will give better understanding as to what we can do to reduce brake failure and what to watch for. The info is from my experiences and my thinking, as to what...

• 2001LC
• Replies: 206
• Forum: 100-Series Cruisers

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[Tinkerer]

99 LX, 236k, no brake issues other than replacing rear pads & rotors at 86k.

Since the wife handed the vehicle to me after that, no more brake issues. Front pads/rotors still original factory parts, never replaced.

I intentionally drive this vehicle gently to minimize drivetrain stresses, including brakes. That means lighter acceleration, lower and more constant speeds, and slowing down more gradually where possible to reduce brake use and peak braking forces. One reason is that I saw the unbelievably overcomplicated brake master cylinder & booster system when I bought it new.

A new booster assembly lists for $2k. Rebuilding it yourself will be extraordinarily time consuming and prone to problems, and the result will not last as long as a new assembly.

The booster pump on this vehicle operates normally at startup. I am disinclined to periodically stress-test that system at startup as advised by some posters here - the more it is used/stressed the sooner it will fail.

Philosophical notes:

Automakers have mostly lost the K.I.S.S. view. This brake system could have been made much simpler even with ABS. But even ABS is dubious - before ABS, developing braking skill under all conditions was a point of pride and a competent alert driver anticipating braking situations didn't need ABS, but as the nanny state grew ABS and other "safety" hand-holding have made the masses even more incompetent and dependent on the hand-holding. Its reaching new levels now with the plethora of "driver assistance" overcomplications in new vehicles.

Few Americans understand the sound basis of my driving style to minimize wear and tear in order to maximize vehicle reliability and life while minimizing overall cost. All they see is a vehicle moving slower than they can stand in their knee-jerk impatience, they don't think about the fact that the few minutes difference in cross-town trip time has a negligible impact on the day, and they have no idea about engine/trans stresses increasing proportional to the square of rpm and high cycle fatigue vs. peak stresses, thermal shock and cycling effects, or brake wear correlated to pressures and pad/rotor temperatures. (See above about mass incompetence.)

 

[wngrog]

You sound like the life of the party.

 

[ScotyDosentKnow]

You sound like the life of the party.

He's probably the only person I have ever seen argue against ABS in a non racing situation lol

 

[NE Snowman]

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