1995 Acura Integra Brakes died while driving

Hi spessegula,

Have you checked the brake fluids and brake pads wear?

If pumping action brings the pedal up, check the wheel bearings, they could be worn causing the clipers to be pushed back very far and this would cause the brake pedal to sink and the whirring noise.

I had the brake rotors and pads replaced yesterday at the mechanic. The brakes now feel firm and very responsive. I drove for about 20 minutes and they were fine...EXCEPT ONCE, when I slowed down at a stop light, they "gave out" again for a couple seconds. I then frantically pumped the brake a couple times and suddenly they were firm and responsive again, just like new.

Can you please help?

Update: The mechanic suggested that it could be a problem with the master cylinder. I.e. some kind of intermittent fluid leak past a seal that would cause the intermittent braking I experienced.

Are there other problems that it could be? The mechanic is now taking a second look, checking the fluids and rear tires.

Mechanic called and said he can not replicate the problem. Said the brakes seem to be working ok. Said there is some moisture around the brake master cylinder but that fluid levels are normal, etc.

Any ideas? I donated, so I'd appreciate a response.

Update: Mechanic thinks it could have been an ABS fluid level issue. He topped off the ABS fluid and said that may have solved it.

Is this likely? I'm pretty tempted to boycott this site as I haven't gotten any responses since my initial post.

Echo echo echo echo

Hi spessegula,

Sorry for the delay in replying.

Seems there is a problem and I am not getting any notification though you have replied.

When the brake pedal sinks, there are 2 possibilities :

1. Failing master cylinder or leaks in system. Do this test and let me know the results. With engine running, slowly depress the brake pedal with minimal force, does the pedal continue to sink? When resistance is felt, hold the pedal for a few seconds and if pressure fails when pedal starts to sink again, problem is a failing master cylinder.
Do you need to top up the fluid regularly? Any leaks would cause the pedal to sink?

2. Air trapped in system. When air is present in system, the first stroke of pedal would normally be much lower than normal and 2ns stroke would bring it up further. If this condition is present, bleed the brake system and retry.

The ABS would not cause such a problem unless the master cylinder fluid is leaking into the ABS pump which is quite common for vehicles of the year.

Does the ABS indicator light come on while driving?

Thank you for the explanation - I was concerned I wouldn't ever get an answer. But I appreciate it.

I performed the test on the brake as you described in #1. Basically, it doesn't seem too abnormal, but there does seem to be less pressure than when I picked up the car a few days ago after the mechanic put on the new pads and rotors. So when I slowly depress the brake pedal it goes down several inches and I meet some resistance. However if I use some force I can push the brake down the rest of the way, but it does require a small to moderate amount of effort.

I haven't needed to top off the brake fluid regularly, in fact I haven't done it at all until the mechanic did it just now.

As for air being trapped in the system, well if you read my initial post, the brake going out happened completely randomly: the second time it happened I was already using the brake to slow down to a stop when it gave out! Then when I took my foot off the pedal and braked again it was fine all of a sudden.

The ABS light has not come on at all. Does this information give any clues?

After going through the above again, some of the things are getting clearer.

" About a week ago I started hearing a faint whirring (almost like a spinning or rotating) sound (while driving) coming from the left side of the front of the car. I did not notice anything unusual about the vehicle's condition and when I looked at the engine I did not notice anything out of the ordinary.
The sound continued most of the time that the vehicle was on. "

The noise should be intermittent and coming from the ABS pump motor. Under normal circumstances it should run briefly and stop. When it runs for too long, the ABS light would show. There could be a possibility the fluid level in ABS was low and has been topped up. However when the fluid level in ABS reservoir starts going down, there should be a leakage somewhere and it most probably is internal.

Since the ABS indicator is not showing, the item that is failing is the brake master cylinder.

Stop vehicle and depress the brake pedal lightly enough to prevent the vehicle from sliding. Hold for 10 seconds, if pedal sinks, the master cylinder is bad.

KH - thank you for the reply. I tried the brake pedal test, and while it seems "slightly" softer than it was after the brake pads/rotors were replaced, the pedal does not sink noticeably.

An update: I spoke to the mechanic today, and he told me that my model of car (acura integra 1995) uses a SEPARATE reservoir for ABS fluid. I.e. does not share with the master brake cylinder.
He told me the ABS module was moist and it took a couple ounces of ABS fluid to top it off. I haven't put any ABS fluid in prior to this (about 1 year).
So is it possible that the ABS module being leaky / low on fluid would cause this (VERY) intermittent brake failure?

Yes, the ABS uses a separate reservoir and the brake circuit are parallel to the ABS system. However I have seen many instances of the ABS modulator leaking internally and when this happens, the fluid is leaking between the two system.

This would cause the ABS reservoir to reduce and brake master cylinder reservoir to increase or the other way round when the brake fluid level decreases and the ABS would overflow.

Yes, the symptoms do point to a failing ABS modulator and could be the cause of the low brake pedal.

If you see any small holes at side of modulator instead of rubber stopper, time to get the modulator replaced. Pressure is leaking internally and modulator being damp means fluid ios leaking from withing the stopper and forced the stopper out resulting in the hole.