Passo Break Pedal Sank down to Floor

[seismic84]

Dear all , On Thursday i was driving to my office ,speed was around 80 km ,suddenly when i required break and pressed the break pedal , it sank to bottom i tried double pedal and some how manged to control the car, i stopped the car to inspect any leakage of break oil ,but everything seemed ok , i drove again but this time with slow pace ,and checked the break which was ok ,after driving some km , again break pedal sank to bottom when i pressed for break , it happen 2 or 3 times ,i took my car to mechanic and he said check if this happen again then you have to change the master cylinder , but from that time till now break is working fine ,not even a single time it failed .
Now what i am worried is what to do ? break is working fine no sinking issue ,but i fear that if it may comes again , should i change the master cylinder? or it was just some blockage due to kachra in break oil .
need your kind suggestions please.

[omersiddiqui5482]

Sir this is something dangerous... You need to get all the seals in the brakes calipers and the rear brake drums plus all the brake fluid pipes checked. This happened to me once turned out be a leaked seal in the rear brake drum. Also check if the brake fluid levels is decreasing. It can also be master cylinder seals but that is a rare occurrence.

Also get all of the brakes serviced and drained and bleeded with a recommended brake fluid.

Be safe

[hash4u]

take it serious and
go to someone else willing to check thoroughly the
master cylinder / brake booster

[anon35615524]

Bro visit some Good Garage which is expert in brakes, and get everything thoroughly checked, inspected and tested; one by one.
The problem which you have explained is extremely dangerous; for you, your car and others.
Be safe and get everything inspected ASAP.

[nfssaad]

this is 100% seal failure or leakage.

check in sequence.

each tyre individually, check for any dampness on the rims inside, and oil trace when car is parked.
if any seal is bad, that tyres cylinder will leak.

check the master cylinder, disconnect the oil hoses of the cylinder, and then plug those holes of the master cylinder. then press brake, if still going to floor, your master cylinder is gone. the proper way to do it would be to use a pressure gauge but mechanics dont have it.

open up master cylinder take out the pistons. wash the cylinder thoroughly with water, and inspect for the bore closely for any scratches or scoring, if the bore is even slightly scratch, replace the master cylinder.

if bore seems to be ok, you can replace the piston seals and maybe it will work.

but in my experience, its better to replace.

in case of brake parts, ALWAYS REPLACE WITH BRAND NEW PART.

NEVER BUY USED BRAKE PARTS.

[nfssaad]

you also need to do a full brake oil flush. as in completely new oil from master cylinder to each wheel

[Thinking]

its brake master cylinder failure and it can malfunction any time.

i got the seals changed (got orignal toyota kit) on my 2D however it kept failing. so eventually i changed the master cylinder with the new one and issue resolved.

incase of brake failure try pumping the pedal (just for the time being since u r using the ride). get it changed immediately.

[sk_cooldayz]

This has happened to me several times in my Passo during the last 1 year. I own this car since last 6 years.

It happens when ABS is triggered while breaking. I have changed the master cylinder and it was fine for next few months but then it again happened. Pumping the break a few times fixes the issue. Does not always happen on ABS but its really very dangerous. One thing to note, although the break paddle sank to bottom, if you press it fully, break still engages and stops the tyres.

[omersiddiqui5482]

Sir this happens to all the cars. when you pushed the paddle to the max there is some force stopping the wheels and slowing the car down.

i had an alto once. the brakepad actually fell down while i was driving and i just heard a noise as if a stone has touched the tyre but when i applied the brakes all of the fluid leaked and the Caliper piston was quite out. but still the car was coming to a stop when i pushed the paddle to the max even with no fluid in the system. the fault was a bad caliper piston seal was damaged causing the brakes to jam and fade.

Had to change the caliper and got the disk resurfaced.

[brownrose78]

@seismic84
@omersiddiqui5482
Confirm your Brake Master Cylinder as well as bottom slave cylinder; one of them is culprit
It happens that randomly it will losse pressure & it will automatically resume next moment.

Your master cylinder & slave have rubber seals inside which got leak due to which vacuum issue happened and brake pedal gets loose.

It happened. I also replaced them with brand "Ultima". Although chinese brand but works good

Main reason of failing such components is usage of poor quality fake brake fluid.
After new cylinder, only use Toyota brake fluid & buy from 3 S dealers.
One box of ordinary brake fluid cost you 150-250 but Toyota will cost you 900 per Bottle

[omersiddiqui5482]

Yes the Best fluid you can buy should be used in case of Breaks. I usually use DOT 3 Seiken or a Toyota

[seismic84]

Thank you for the suggestion will go for it .

[seismic84]

seal failure of master cylinder right ? but one thing is strange its never happened again .

[nfssaad]

it means micro particles in the brake fluid. disturbs the seals.

like i said complete flush of brake oil is required.

brake oil must be almost transparent like water, with a slight yellow tint.

[seismic84]

thank you for the suggestion definitely gonna check all network regarding break system .

[seismic84]

yes it get slow but cant help in emergency . need to find out the culprit .

[seismic84]

Probability ratios of master cylinder are greater , mechanic told me that some times micro particals raise this kind of issue if its not failing every time .

[sajidpu.25]

Same spongy brake issue with my passo 2011 model..brake goes down but car stops, seems like if need it in emergency, might not work properly. Paddle goes down with spongy feeling.
How did you solve that problem..

[omersiddiqui5482]

It is the master cylinder Bhai have it replaced or overhauled...

[pwuser15925789606]

Did it already but in vain..
All the break pads and shoes replaced as well..