[gou]

I own an OHC AT 2002 model, driven around 89000 kms. Yesterday, my wife was driving it and was on her way to office when its brakes started becoming less responsive and eventually failed. The brake paddle was getting fully pressed without any effective braking at all. Even the parking position (P on lever) was not working. The car hit an auto and that is how it stopped. Since brakes where not responding properly, my wife was already driving it slowly and fortunately there were no eventualities. My wife called me and I reached the place. In the meantime some strangers helped her park using the stones to stop the car.

We took a nearby mechanic to check it and on reaching the place found that brakes were working fine - no problem at all. Brake fluid was near Max level and pads also looked fine. He was also not sure what the problem might be, but suggested that there might be small hole in booster pump from where if air leaks suddenly it might cause failure. He asked to bring the vehicle next day for thorough check up since it might take half day to one day time. He also mentioned that he might need to remove the wheels and check. Not convinced by his theory I decided to check it with Honda.

I visited Magnum Honda on Kanakpura and asked SA Satish Shetty to check. The SA drove and said there is no problem and I can drive it freely. Suggested that may be mat might have come between brake and caused the problem. Not satisfied with his suggestion - since even Parking lever was not working - I asked him to check thoroughly. It was evening 6pm and closing time, but he asked one guy who was on verge of leaving for the day to check it. He took the car in and after around 15-20 mins came out mentioning that he has checked everything thoroughly (including booster and cylinder) and there is no leakage and no problem at all. I told Honda guy about a possible air leakage in booster pump but he said in that case brake fluid level goes down. I could not get a clear reply from them regarding why it could have failed.

My neighbour told me that sometimes if some oil or other fluid falls on disc then it might reduce the friction and cause failure or low responsiveness in brakes. Later when it clears or evaporates the brakes start working fine.

So there are 3 reasons I got from 3 different people:

1. Air leakage in booster pump from local mechanic. Honda guy said this would cause brake fluid level to go down, which did not happen. I am not on technical details of this.
2. Honda SA suggesting mat to come below the pedal. I think this was not the case since even the parking level marked on the lever was not working and also later on I did not find it to be the case. I think this was taken from Toyota recall case in US
3. My neighbour's suggestion of oil collecting on brake disc. This looks more like it, but I am wondering how it might happen

After that I have driven car for 30-40 kms without any problem.

I don't have much technical knowledge on this and want to know what should be next steps. Whether we should drive it or not? Does it need further check up? Since my wife drives it daily for her office and often my 3 months daughter also travels in it, I want to be doubly sure of this.

Moderators, please move it to respective forum if this is not the correct one.

[11mahesh11]

i think i too experience this on my dzire vxi sometimes but to a smaller extent as if the brakes have lost their braking prowess but pressing the clutch and leaving it seems to regain the braking.
i too would like the experts to throw some light on this.

[sgiitk]

A very surprising event. Please do keep up posted.

A few points. Since the fluid level is unchanged so a leak can be ruled out. Full pedal depression means to transfer the pressure to the master cylinder (almost always happens to due fluid loss which is not the case here) is not there, but the pedal travel is.

So I will not suspect the hydraulics but the mechanical linkage of the pedal to the servo & cylinder. Normally, servo malfunction just leads to mare braking effort. Of course if the sensitizer ring has issues then it may become less (why it is called the sensitizer and not the desensitizer ring beats me).

[ssh1979]

A very scary situation. More worrying that it is not reproducible for you have to live with the fear that it might occur again (God forbid!). When is your next service due? You might want to ask him to thoroughly check the complete brake assembly (as you mentioned they didn't on that day) and replace any faulty/worn out parts? 89K is a good good amount of kms. Until then, I would suggest you not to drive.

[pranavt]

Change to better brake fluid. Since it's an automatic, chances are that your wife was riding the brakes while driving, leading to overheated brake fluid.

[MAS]

Originally Posted by pranavt

Change to better brake fluid. Since it's an automatic, chances are that your wife was riding the brakes while driving, leading to overheated brake fluid.

+1

Brakes fade due to overheating and this could be the case. But why did the car not stop when it was shifted to "P" in the AT. This is very strange. Also for shifting to "P", one has to go through "N" (Neutral), "R" (Reverse). If this has not worked, there is something major that is wrong with the AT.

The car is no longer safe to drive (especially as it is driven by your wife). Would suggest to dispose it immediately and get a new/pre-worshipped one.

[gou]

Originally Posted by sgiitk

A very surprising event. Please do keep up posted.

A few points. Since the fluid level is unchanged so a leak can be ruled out. Full pedal depression means to transfer the pressure to the master cylinder (almost always happens to due fluid loss which is not the case here) is not there, but the pedal travel is.

So I will not suspect the hydraulics but the mechanical linkage of the pedal to the servo & cylinder. Normally, servo malfunction just leads to mare braking effort. Of course if the sensitizer ring has issues then it may become less (why it is called the sensitizer and not the desensitizer ring beats me).

So what all do I need to check in this case?

Originally Posted by ssh1979

A very scary situation. More worrying that it is not reproducible for you have to live with the fear that it might occur again (God forbid!). When is your next service due? You might want to ask him to thoroughly check the complete brake assembly (as you mentioned they didn't on that day) and replace any faulty/worn out parts? 89K is a good good amount of kms. Until then, I would suggest you not to drive.

I got servicing done 20-25 days back. Everything was checked and was reported fine.

Yeah, I am also planning to do a thorough check on it. But want to know what all should be checked and how.

Originally Posted by pranavt

Change to better brake fluid. Since it's an automatic, chances are that your wife was riding the brakes while driving, leading to overheated brake fluid.

I don't think that would be the case. She has been driving it for 1.5 yrs now and uses only right leg to manage both accelerator and brake

[Captain Slow]

Originally Posted by gou

I own an OHC AT 2002 model, driven around 89000 kms. Yesterday, my wife was driving it and was on her way to office when its brakes started becoming less responsive and eventually failed.

Were the roads wet/raining when this happened? If water gets into the brake drums, brake performance may become poor and unpredictable.
Once dried up the brakes go back to their normal effectiveness.

[pranavt]

Replace brake fluid, then report back. During this process, the brakes will be bled too, which is another option. They're the cheapest options anyways.

[sgiitk]

Originally Posted by gou

Even the parking position (P on lever) was not working.

Did you mean on the gear selector. Then there is a serious AT problem in addition. When you select P, a mechanical Pawl drops to immobilize the transmission.

I will not say the electronics, since the ECU does not have anything to do with the brakes.

If you meant the parking brake lever, then again it is very odd. The hydraulics pack up, and then the mechanical linkage (to the rear only) also packs up! My suspect are the common elements, the brake linings in the rear drums! With age the linings tend to come off, due to adhesive failure (5-7 years typical). Linings coming off does lead to the brake pedal dropping to the floor. Happened in my Santro but then Fluid Level also fell. How come the brakes are back beats me.

[gou]

Originally Posted by Captain Slow

Were the roads wet/raining when this happened? If water gets into the brake drums, brake performance may become poor and unpredictable.
Once dried up the brakes go back to their normal effectiveness.

For a change it did not rain yesterday and roads were not wet. If you see 3rd point in my first post, my friend also suggested that oil or water might cause this issue and once it evaporates it will be fine.

Originally Posted by pranavt

Replace brake fluid, then report back. During this process, the brakes will be bled too, which is another option. They're the cheapest options anyways.

Yeah I am also thinking of changing the fluid for sure. Just want to get the list of things before I head over to garage.

Originally Posted by sgiitk

Did you mean on the gear selector. Then there is a serious AT problem in addition. When you select P, a mechanical Pawl drops to immobilize the transmission.

I will not say the electronics, since the ECU does not have anything to do with the brakes.

Yes, I meant gear selector - could not get the exact term for it. So apart from brakes do I need to check something for AT transmission also?

[Rehaan]

Originally Posted by gou

...brakes started becoming less responsive and eventually failed. ...
Since brakes where not responding properly, my wife was already driving it slowly and fortunately there were no eventualities.

Please tell her to STOP the car completely and immediately when this happens. She might think driving slowly is safe enough, but its a huge danger for her and moreso pedestrians and bikers around her.

Originally Posted by gou

...The brake paddle was getting fully pressed without any effective braking at all.

At this point it seemed like a fluid leak, but since fluid had not leaked at all, and the brakes came back to normal, this is not the case.

It could be one of the following :

- Pads lost their effectiveness (due to excessive heat, oil on them, etc)
- Booster stopped functioning (leak in booster, vacuum pipe, etc)
- Master cylinder failing somehow? (i dont know)
- Something stuck behind the brake pedal

Originally Posted by gou

...Even the parking position (P on lever) was not working.

Like other have said -- this part just doesn't compute?!?

Are you saying your wife managed to put the gear lever from "D" past N, R and into "P" while the car was moving (this seems unlikely)?

Or could she just not manage to move the car past D/N into R or P?

Assuming the car was at some point in "P" - it still continued to move??

Please get a clear picture from her.


Also - did she try and use the hand-brake / Emergency brake?


What you need to do before moving forward is try and figure out if :
A) It was a one-time human error (eg. overheating brakes, object behind pedal, etc)
OR
B) Some sort of intermittent mechanical failure that WILL happen again.


cya
R

[dhanushs]

Originally Posted by gou

For a change it did not rain yesterday and roads were not wet. If you see 3rd point in my first post, my friend also suggested that oil or water might cause this issue and once it evaporates it will be fine.

• Gou, if there is water or oil between the pads and disc, there would be reduced braking effectiveness, but still the pedal WOULD NOT go all the way in. If it had gone, then please rule out the possibility.
• Regarding the 2nd possibility, your wife should have recognized the pedal travel. The pedal travel when a floor mat comes in between and the when the pedal goes all the way in is very different.

The only possibility I see is Air in the System. As a 1st step, change the brake fluid and bleed the air in the system by a competent mechanic. After which, take the car out to an open area with no traffic and test the brakes hard (the ABS activating types), many times. If there is an Air leakage in the system, then atleast one time, the brakes will fail. If it does not fail, then you are good to go.

EDIT:

Originally Posted by Rehaan

- Pads lost their effectiveness (due to excessive heat, oil on them, etc)
- Booster stopped functioning (leak in booster, vacuum pipe, etc)
- Something stuck behind the brake pedal

Hi Rehaan,

For all the problems you have mentioned, the brake pedal travel wont increase. I guess it will just get hard. Hence I suspect Air in the lines or master cylinder.

[Rehaan]

@dhanushs

Nowhere has gou said that the pedal travel increased. He only mentioned "The brake paddle was getting fully pressed". There is a lot of uncertainty/vagueness, which is why i've suggested he ask his wife a few more things.

But yes - air in the lines is another point i could have listed (along with overheating brake fuel, due to riding the brakes as pranavt mentioned).

cya
R

[sgiitk]

Originally Posted by gou

Yes, I meant gear selector - could not get the exact term for it. So apart from brakes do I need to check something for AT transmission also?

As Rehaan has pointed out, you should NOT be able to move into P when the moving. In the new ATs it will not go into P unless the Stop pedal is firmly pressed. Let us assume that the pedal was firmly pressed, and the car was somehow shoved into P.

Then the car with stop with an almighty jerk, and there is very likely to be severe mechanical damage to the transmission.