Any other warning signs / precursors to brake booster failure? (1 Viewer)

[nukegoat]

My dashboard is a christmas tree right now already. I should have done tone rings on my axle swap(s) but I assumed I might swap the booster anyway for something that has a larger master cylinder. Come to find out, the factory booster/MC works well (though I'm sure it's working harder than it did before) and stops the rig just fine.

So with a ~200K mile rig, I don't have the privilege of having some sort of warning light pop up on the dash in a "novel" way since those lights are already on anyway. If I were constantly monitoring techstream, or something, I could disambiguate the codes and pay attention if the system indicated some unique failure, but that's impractical.

Is there another way of getting a last minute warning before the booster takes a dump? Or am I probably best off either swapping it for hydroboost anyway and/or replacing the motor proactively?

 

[JunkCrzr89]

Although I’ve not experienced the failure (knock on wood), from what I can tell you’ll get a warning buzzer when the booster starts declining to death. Also, the booster motor is arguably the most common failure point, which typically makes an awful screeching racket when failing. Cheap insurance in your case might be to just prematurely pull the booster motor and have it rebuilt (~$300) or rebuild it yourself.

 

[nukegoat]

Although I’ve not experienced the failure (knock on wood), from what I can tell you’ll get a warning buzzer when the booster starts declining to death. Also, the booster motor is arguably the most common failure point, which typically makes an awful screeching racket when failing. Cheap insurance in your case might be to just prematurely pull the booster motor and have it rebuilt (~$300) or rebuild it yourself.

Part of me wonders if my booster was already swapped. The accumulator has some weird rust spots on it that are atypical for a California rig

 

[JunkCrzr89]

Part of me wonders if my booster was already swapped. The accumulator has some weird rust spots on it that are atypical for a California rig

Mine was originally a SoCal rig and also has odd rust spots on the accumulator. No record of the booster, motor, or accumulator ever having been changed.

 

[nukegoat]

Mine was originally a SoCal rig and also has odd rust spots on the accumulator. No record of the booster, motor, or accumulator ever having been changed.

Hmm ok.

 

[87warrior]

When my booster died it gave me a sign when I started the cruiser. With my foot on the brake pedal, the pedal went to the floor when I started it and the buzzer of death played its tune. Turned the cruiser off and back on and the buzzer went quiet... and the booster worked on the 20 mile drive home. This happened at 320k miles. I never heard the booster motor scream.

 

[CorporalClegg]

I just wait for the day mine leaves me stranded in back country. Best I could say is to pay close attention to how often/long the motor runs especially on a cold start. At the rate your truck is going I'd look into a vacuum booster conversion, but that's just me.

 

[nothappening]

I just wait for the day mine leaves me stranded in back country. Best I could say is to pay close attention to how often/long the motor runs especially on a cold start. At the rate your truck is going I'd look into a vacuum booster conversion, but that's just me.

What is the rule of thumb here? I swear I've seen @2001LC say that as long as your rig passes the test:

Pump brake pedal 40 times.
Check that fluid level is now at max line (no higher or lower)
IG key to on. Start timer.
Time how long brake booster motor runs. Spec is 30 to 40 seconds.

Then how often the motor runs/how long it runs isn't much of a concern. I could be wrong, but the brake failure is always in the back of my head while driving, so I'm just trying to get as much info as possible.

 

[CorporalClegg]

What is the rule of thumb here? I swear I've seen @2001LC say that as long as your rig passes the test:

Pump brake pedal 40 times.
Check that fluid level is now at max line (no higher or lower)
IG key to on. Start timer.
Time how long brake booster motor runs. Spec is 30 to 40 seconds.

Then how often the motor runs/how long it runs isn't much of a concern. I could be wrong, but the brake failure is always in the back of my head while driving, so I'm just trying to get as much info as possible.

I couldn't put a time on it past the fsm "test" (that I'm not privy to) I've noticed mine runs after sitting more than 3-5 days for 10 - 15 seconds if that time increases I would be more concerned. Mine started to run longer but after finding a small leak in a line at the rear of the truck and performing a proper bleed that time reduced. I'm at 270k & 22 yrs I believe it to be oe

 

[riffman12]

You will hear the sound of a dying seagull coming from around your booster. It will be very audible from inside the car.

On top of that you will get a very loud buzzer inside the car. Once you hear that stop as quickly as possible as it basically means you have 5-6 more brake presses until it goes to the floor.

 

[Keowee]

Mine would make a loud chirp for a second or two on cold mornings after start up. I guess the seagull was trying to warn me what was coming.

A few weeks later it was screaming bloody murder with no brakes. It had about 160,000 miles on it.

 

[mitchjohnson000]

Hydroboost would probably be the best solution for a truck of your weight/tire size. It might not be the right choice given the amount of time/fab required to build it.

I say leave it unless you are gonna go hydroboost.

 

[nukegoat]

Hydroboost would probably be the best solution for a truck of your weight/tire size. It might not be the right choice given the amount of time/fab required to build it.

I say leave it unless you are gonna go hydroboost.

Yeah, my challenge is that I dont want to limit overall flow to the box, especially with ram assist

 

[Eyedaho]

I have been wondering the same thing, since my rig has a little over 300k on it and I'm not sure if any under hood brake components have been replaced. I noticed something this spring that has me wondering. With the Covid scare, the common dining areas at my work are closed, so I eat in my car. When it was cold out this spring,I would turn my car to the on position so I could have the seat heater on. I noticed that every 15-20 minutes, my booster motor turns on for a few seconds. This leads my to believe that I'm bleeding of pressure, either from the accumulator or somewhere else in that vicinity. Since I'm not actuating the brakes, I don't think it could be related to a line or caliper. This makes me wonder if I should proactively start swapping out components in that system, but I don't want to throw away money if it's not necessary.

 

[mitchjohnson000]

Oh yeah, I forgot that you were having those PS pump issues. Adds another variable to the situation. You could add another PS pump kinda like this GM LS Truck Dual Power Steering Pump Brackets – Goat Built . Once again, that would be a ton of work and more of a blue sky project. Maybe just LS swap it at this point lol.

 

[Rpreme]

What is the rule of thumb here? I swear I've seen @2001LC say that as long as your rig passes the test:

Pump brake pedal 40 times.
Check that fluid level is now at max line (no higher or lower)
IG key to on. Start timer.
Time how long brake booster motor runs. Spec is 30 to 40 seconds.

Then how often the motor runs/how long it runs isn't much of a concern. I could be wrong, but the brake failure is always in the back of my head while driving, so I'm just trying to get as much info as possible.

I think this is the rule of thumb. The Original owner I bought my LC from said the same thing. He demonstrated this same scenario and booster ran for about 30 secs. I too have rust spots on my accumulator being a cali shell, and would like to know when it is about to go. I currently have 170k and am paranoid from time to time..

 

[saucebox]

It seems like one of the common failures is the wire between the components in the cylinder. It rusts up, changing the resistance, and potentially causing the booster motor to work too hard. I think this is one of the things @2001LC was chasing.

The wire on the left here—both sides are under the rubber cap. You're looking at the bottom of the assembly, so the caps are underneath and actually hold any moisture or spilled brake fluid.

Pic shamelessly stolen off the internet.

I don't know if there's much you can do but clean them (and they're kind of a PITA to access anyway), but knowing their condition might tell you more about the booster. Like if they're totally crusty, it might be time to start planning for a new unit.

 

[FxFormat]

Before it dies, you'll get some creaking noises in the booster, when it fails to hold pressure it'll leak into the MC and you'll see bubbles, along with some crow squawking noises, EHHH EHHHH EHHH. After that you'll get a high pitch ringing noise in the dash, if you continue to ignore that then you'll probably plow into a tree shortly after.

 

[spc7669]

I just wait for the day mine leaves me stranded in back country. Best I could say is to pay close attention to how often/long the motor runs especially on a cold start. At the rate your truck is going I'd look into a vacuum booster conversion, but that's just me.

How does one do the vacuum booster conversion? Mine isn’t giving problems right now but I’m not pumped about spending that much coin to replace this system.

 

[Ayune]

When my brake booster turns off there’s a clank noise. Doesn’t happen every time, maybe every 5th time the booster runs. Just started today, 317k on my ‘98 LC. Initial pressurization time is ~40 seconds. Engine isn't running in video.

Am I doomed?