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Brake system failure


K.o.N.o.S

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Hi members, yesterday when I was driving my Demio when drepressing suddenly brake pedal went all the way to the floor. Luckily I was near a garage & took the car for inspection right away..however after about 10min or so brake system came back to normal without having to do any repairs..I searched the forum/Net and found out that,

1- Could be a brake fluid leak- which was not the case & the mechanic did a through inspection 

2- Error in the braking booster- highly unlikely according to mechanic’s advice 

3- failure in braking master cylinder- which mechanic suggested that if the issue happens again he will do an inspection on the component.could be an internal issue he said.

he advised me to drive the car normally for the moment and not to panic.

I am skeptical and I need a second opinion on this and appreciate if you guys could shed some light.

thank you.

Edited by K.o.N.o.S
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That's a bit scary. :(

Did the pedal sink to the floor when braking suddenly (possibly activating ABS) or was it a regular press on the pedal? If it was the former, you might want to get your ABS module checked out. It might be a valve stuck open/closed that's causing the issue. It might also be a faulty wheel speed sensor detecting slippage and activating ABS. Note that these are all assumptions.

Can you do a test where find an empty road, bring the car upto speed and slam on the brakes to check if ABS kicks in as expected? 

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2 hours ago, iRage said:

May I ask how long and where you were driving to and how you were driving ? Are you sure you didn't excessively heat up the brakes after some spirited driving (or some other reason that might have contributed to it)?

 

Could be..Because the road leading upto my house is very narrow & bumpy (about 1.5 km from the main road) so most of the time I have to depress the padel to slow down..for the record I do not rest my foot on the brake pedal. I did about 20 min of driving 

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4 hours ago, Davy said:

That's a bit scary. :(

Did the pedal sink to the floor when braking suddenly (possibly activating ABS) or was it a regular press on the pedal? If it was the former, you might want to get your ABS module checked out. It might be a valve stuck open/closed that's causing the issue. It might also be a faulty wheel speed sensor detecting slippage and activating ABS. Note that these are all assumptions.

Can you do a test where find an empty road, bring the car upto speed and slam on the brakes to check if ABS kicks in as expected? 

Davy, it was just a regular press to slow down in a very bumpy area of the cross road leading up to my house.

Actually yesterday I did some testing and everything seems normal.ABS kicked in as expected. The mechanic was with me the whole time ( he’s a relation of mine).Anyway he’s very firm on the fact that a worn out master braking cylinder could be the underlying cause.Even though the system works fine the problem might surface anytime soon. That is according to his advice .Now I am kind of scary to drive the car..?

Edited by K.o.N.o.S
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On 9/16/2018 at 2:48 PM, K.o.N.o.S said:

Hi members, yesterday when I was driving my Demio when drepressing suddenly brake pedal went all the way to the floor. Luckily I was near a garage & took the car for inspection right away..however after about 10min or so brake system came back to normal without having to do any repairs..I searched the forum/Net and found out that,

1- Could be a brake fluid leak- which was not the case & the mechanic did a through inspection 

2- Error in the braking booster- highly unlikely according to mechanic’s advice 

3- failure in braking master cylinder- which mechanic suggested that if the issue happens again he will do an inspection on the component.could be an internal issue he said.

he advised me to drive the car normally for the moment and not to panic.

I am skeptical and I need a second opinion on this and appreciate if you guys could shed some light.

thank you.

If you or the mechanic can't find any leaks or any problem with the ABS system I have some questions to ask.

1. Was the Air Conditioning System (HVAC Climate Control System) ON at the moment you felt this sinking of the brake pedal? 
2. And is this the very first time you experienced this or have you felt this happening at random intervals without any apparent issue of the braking system?

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6 hours ago, Jason_Bourne said:

If you or the mechanic can't find any leaks or any problem with the ABS system I have some questions to ask.

1. Was the Air Conditioning System (HVAC Climate Control System) ON at the moment you felt this sinking of the brake pedal? 
2. And is this the very first time you experienced this or have you felt this happening at random intervals without any apparent issue of the braking system?

Hi. 

1.Yes the AC was on 

2. This is the first time I encountered this issue. I have been driving the car for two days since the issue and as of now braking system is working smoothly.

Edited by K.o.N.o.S
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21 hours ago, K.o.N.o.S said:

Davy, it was just a regular press to slow down in a very bumpy area of the cross road leading up to my house.

Actually yesterday I did some testing and everything seems normal.ABS kicked in as expected. The mechanic was with me the whole time ( he’s a relation of mine).Anyway he’s very firm on the fact that a worn out master braking cylinder could be the underlying cause.Even though the system works fine the problem might surface anytime soon. That is according to his advice .Now I am kind of scary to drive the car..?

If it was a master cylinder issue, the brake pedal will consistently behave the same way. So I hardly think that's the issue.

Once you were in the garage, did you bleed the brake system and check if there was air in the system? Also, was there a repair in the brake system done or at least a brake fluid change done recently? 

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1 hour ago, Davy said:

If it was a master cylinder issue, the brake pedal will consistently behave the same way. So I hardly think that's the issue.

Once you were in the garage, did you bleed the brake system and check if there was air in the system? Also, was there a repair in the brake system done or at least a brake fluid change done recently? 

No. I haven’t done any maintenances or repairs to the braking system after I bought the car ( about 1 year ago). If the air had trapped internally it would have behaved the same way consistently correct? Why the system suddenly came back to normal? I am on the run for about 3 days now and no issues so far. Unfortunately we couldn’t bleed the system..maybe it slipped my mind & mechanic’s mind as well..thank you for enlightening.

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5 minutes ago, K.o.N.o.S said:

No. I haven’t done any maintenances or repairs to the braking system after I bought the car ( about 1 year ago). If the air had trapped internally it would have behaved the same way consistently correct? Why the system suddenly came back to normal? I am on the run for about 3 days now and no issues so far. Unfortunately we couldn’t bleed the system..maybe it slipped my mind & mechanic’s mind as well..thank you for enlightening.

Depends on where air is trapped. If there was air not big enough to cause a consistent issue, but sufficient enough to throw the ABS module out of whack (especially once the system heated up causing the air bubble to expand), then it could have caused the issue. But if there was no repair done, this is probably not the case.

So yeah, maybe you can try bleeding out the system and keep an eye out for any air that's purged out. If you hook up a transparent tube to the bleeder valves and bleed the system, you will see air bubbles coming out as you pump the pedal. Make sure to keep the reservoir topped up during the process to avoid air reaching the ABS module. 

By the way, you can do a simple test on your own to determine if the brake booster is leaking. Follow the steps in the post below:

 

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7 hours ago, Davy said:

Depends on where air is trapped. If there was air not big enough to cause a consistent issue, but sufficient enough to throw the ABS module out of whack (especially once the system heated up causing the air bubble to expand), then it could have caused the issue. But if there was no repair done, this is probably not the case.

So yeah, maybe you can try bleeding out the system and keep an eye out for any air that's purged out. If you hook up a transparent tube to the bleeder valves and bleed the system, you will see air bubbles coming out as you pump the pedal. Make sure to keep the reservoir topped up during the process to avoid air reaching the ABS module. 

By the way, you can do a simple test on your own to determine if the brake booster is leaking. Follow the steps in the post below:

 

Adding to what Davey said, there's a Method to get rid of the Air in ABS Module using a scanner called "Auto Air Bleeding ABS Module". this will require a fully fledged scanner like launch creed or you might need to consult the the Agents. below link contains how it has been done. once this is done, air trapped inside the Module will enter the brake lines and you should follow the normal bleeding process (Pedal Pump or Vacuum Machine method) to get rid of the trapped air in the lines. you can do this in manual way by Slamming the brakes on a gravel road or ground (where there's no traffic) to activate the ABS and activate all the solenoids in the ABS module, but doubt the success.

 

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15 hours ago, K.o.N.o.S said:

Hi. 

1.Yes the AC was on 

2. This is the first time I encountered this issue. I have been driving the car for two days since the issue and as of now braking system is working smoothly.

As per my experience in my Civic FD when I've set the Climate Control System to "Auto" mode some interesting thing happens.
If I'm stopped in traffic with the brake pedal pressed and AC compressor kicks in, the pedal sinks to floor. (Like 1 inch from the bottom point if no fluid in the system)
This behaviour was so mysterious to me to diagnose or pinpoint the root cause at first. But after much research and testing the brake system for faults it seems when the AC kicks in, the engine vacuum drops very slightly under low rpm which causes brake pedal to sink. After finding the exact cause I tried to observe this very carefully. So even when we are travelling very slow under low rpm (under 1000rpm exactly like your scenario) if you timed the braking just when the AC kicks in, this happens. It's how our engines work. Nothing wrong completely normal. Maybe you timed it randomly. How long have you been driving this car?

Just to add there's a very simple way to check the brake system for leaks. (Or atleast get an idea)

1. Turn off the engine and put the gear to P then apply hand brake.

2. Pump the brake pedal till  it rises up to the max point.

3. Then press the brake pedal as hard as you can and hold it there for more than 30 seconds.

4. If the brake pedal sinks from it's initial position there's definitely air in the system or worse there's a leak in either hoses or internal components. Examine further.

But if brake system passes above check and you can see no code for ABS system when scanned I wouldn't worry! 

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13 hours ago, Jason_Bourne said:


If I'm stopped in traffic with the brake pedal pressed and AC compressor kicks in, the pedal sinks to floor. (Like 1 inch from the bottom point if no fluid in the system) 

 

I didn't understand this part... Did you mean there's only 1 inch of clearance between the floor and the brake pedal when the brakes are functioning normally? According to my owners manual, it should be 3+ inches (85mm)

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48 minutes ago, Kelly said:

@K.o.N.o.S May be give a call to mazna get their opinion as well . Since they may have experience this in other vehicles. 

I do not think  this is a Master Cylinder related issue. 

Hi, is there a specific person at Mazna motors that I could get advice on this with?

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19 hours ago, Jason_Bourne said:

As per my experience in my Civic FD when I've set the Climate Control System to "Auto" mode some interesting thing happens.
If I'm stopped in traffic with the brake pedal pressed and AC compressor kicks in, the pedal sinks to floor. (Like 1 inch from the bottom point if no fluid in the system)
This behaviour was so mysterious to me to diagnose or pinpoint the root cause at first. But after much research and testing the brake system for faults it seems when the AC kicks in, the engine vacuum drops very slightly under low rpm which causes brake pedal to sink. After finding the exact cause I tried to observe this very carefully. So even when we are travelling very slow under low rpm (under 1000rpm exactly like your scenario) if you timed the braking just when the AC kicks in, this happens. It's how our engines work. Nothing wrong completely normal. Maybe you timed it randomly. How long have you been driving this car?

Just to add there's a very simple way to check the brake system for leaks. (Or atleast get an idea)

1. Turn off the engine and put the gear to P then apply hand brake.

2. Pump the brake pedal till  it rises up to the max point.

3. Then press the brake pedal as hard as you can and hold it there for more than 30 seconds.

4. If the brake pedal sinks from it's initial position there's definitely air in the system or worse there's a leak in either hoses or internal components. Examine further.

But if brake system passes above check and you can see no code for ABS system when scanned I wouldn't worry! 

Thanks Mr Bourne..will give this a try.☺️

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6 hours ago, Hyaenidae said:

I didn't understand this part... Did you mean there's only 1 inch of clearance between the floor and the brake pedal when the brakes are functioning normally? According to my owners manual, it should be 3+ inches (85mm)

 yeah maybe 3 inches. What I implied was that the pedal sinks lower than its normal position when brakes are applied

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20 hours ago, Jason_Bourne said:

As per my experience in my Civic FD when I've set the Climate Control System to "Auto" mode some interesting thing happens.
If I'm stopped in traffic with the brake pedal pressed and AC compressor kicks in, the pedal sinks to floor. (Like 1 inch from the bottom point if no fluid in the system)
This behaviour was so mysterious to me to diagnose or pinpoint the root cause at first. But after much research and testing the brake system for faults it seems when the AC kicks in, the engine vacuum drops very slightly under low rpm which causes brake pedal to sink. After finding the exact cause I tried to observe this very carefully. So even when we are travelling very slow under low rpm (under 1000rpm exactly like your scenario) if you timed the braking just when the AC kicks in, this happens. It's how our engines work. Nothing wrong completely normal. Maybe you timed it randomly. How long have you been driving this car?

Just to add there's a very simple way to check the brake system for leaks. (Or atleast get an idea)

1. Turn off the engine and put the gear to P then apply hand brake.

2. Pump the brake pedal till  it rises up to the max point.

3. Then press the brake pedal as hard as you can and hold it there for more than 30 seconds.

4. If the brake pedal sinks from it's initial position there's definitely air in the system or worse there's a leak in either hoses or internal components. Examine further.

But if brake system passes above check and you can see no code for ABS system when scanned I wouldn't worry! 

I just performed the above test twice and as per the 4th point the padel did not sink to the floor.?

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Guys I have bleeded the braking system and the system is working as expected. Will let you know if something unusual happens in the future.Thanks all for your valuable advice and guidance..Cheerz!!

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