Impending Brake booster failure?

[Ocho77]

This happened on my drive home this evening. 2002 and not sure any of the ABS components have ever been replaced.

The truck stops fine and the brakes feel great still. Brake fluid level is full. Some research shows it could be the booster pump, but I couldn’t find much with these lights and sounds.

 

[medtro]

 

[Ocho77]

View attachment 4135040

Thanks! Should be viewable now.

 

[Dirt J]

Yes, that's usually the sign. Have you done the pump run time test?

 

[Ocho77]

Yes, that's usually the sign. Have you done the pump run time test?

That’s what I figured. I have not, but read a little about it last night. I’ll do it when I get home today. If I remember correctly, turn the key on and see if it doesn’t run at all, or runs more than 20 seconds - if either of those it’s no good? Could just be the pump motor?

 

[Dirt J]

That's part of it. But the first part is 40 pumps of the brake pedal with key OFF. Then turn key to ON (not run) and time how long the pump runs (buzzing sound). Should be under 30 seconds, if I recall?

Process is embossed on the brake fluid reservoir and documented around here somewhere too. I'll see if I can dig up.

EDIT: shown here.

 

[BullElk]

Yes you can just replace the pump motor if you wish. I replaced just the motor recently on my '06 LX and now everything works fine. Even iif it only lasts a year, it was worth the $60 motor and the education.

 

[Ocho77]

Did the test. Pumped the pedal 40 times and it stayed firm. Turned the key on and the pump ran for about 5 seconds. Started the truck and moved around the drive. No lights or buzzers and stopped just like normal. Brake fluid level stayed about midway between min/max.

 

[2001LC]

The Lights & Alarm, indicate pressure drop. The screeching sounds in background, sounds like failing seal in master.. Look at your master from the front.
See if bubbles come up from front of reservoir as screeching sound heard. YES! You'll need a new booster ASSY with master (the whole brake master)

Thread 'Brakes ...... 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

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• 

 

[leveeguy]

deleted

 

[Ocho77]

The Lights & Alarm, indicate pressure drop. The screeching sounds in background, sounds like failing seal in master.. Look at your master from the front.
See if bubbles come up from front of reservoir as screeching sound heard. YES! You'll need a new booster ASSY with master (the whole brake master)

Thread 'Brakes ...... 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

• 
• 

I had read your thread. Thank you! I’ll have to decide whether it’s worth tackling all this. The truck has 490k miles on it…and some rust. Might be time to let her go…, though it runs flawlessly.

 

[2001LC]

Miles not a big deal. Rust may be.

I don't usually recommended used brake master. But I just pulled a working one, from a 2005 w/~200k+. It was R&R, as a PM.

DM me, if interested in it.

 

[2001LC]

The things to look/listen for closely.
Do you hear a "screeching sound" and see "bubble" coming up front of reservoir at same time. YES! New master is needed.
This happens at first on cold mornings, at first start. When brake fluid & rubber seals cold. As they heat with brake use, sound goes away (seal expand with heat). Over time, seal gets worst. Screeching sound heard, even after warm up. In time, booster system can't keep pressure replaced, as fast as bad seal bleeds it off. Booster motor runs excessively long duration, and motor burns up. NO motor, NO BRAKES!

Second, look for, any leaks on master. Like between black plastic (ABS unit) and body of master. New master needed.