Civic Vx brakes problem

[GasSavers_BIBI]

Ok, so my civic Vx 92 just had me a litle bit scared today. I was doing 15mph going slowly in neutral to the red light, then I pushed the brakes and nothing happen I had the pedal to the floor. So I started pumping the brakes, and the pression came bake. So I want to a parking to test it again and it was the same, the pression was missing, I had to pump them to have the brakes back. So I went to see my mechanical, about 5miles, and the first 3miles, the car would brake normaly, but then all came back all right. Still I had it check and he looks at the brakes oil and it was find. So it told me that it was probably the master. Since then its ok so I don't know, a rebuilt master would be 150 installed with taxes.

What else could it be, or is that really the "brake master"?

[GasSavers_TomO]

Brake master cylinder or the brake booster could be at fault.

You might have developed a leak on one of the brake lines that is letting air into the system. Try bleeding the brake system first, it is cheap and easy.

[Danronian]

Sounds to me like the master cylinder. I've had many Honda ones go bad on me before. If it were a front or rear brake line leaking, you would see the fluid level in the brake resevoir dropping. It could be the brake booster, but with those they generally are good or bad, usually no between.

[GasSavers_bobski]

If you had a leak that lets air into the system, it almost certainly would let fluid leak out as well. If you haven't lost any brake fluid, it's almost certainly the master cylinder.
If you're doing the work yourself, it wouldn't hurt to try bleeding the brakes - it's only a couple dollars worth of brake fluid. But if you're paying a mechanic to do the work, it's probably a waste of money.

[kamesama980]

brakes leaking will not let enough air in (and hold it) to maintain the same level in the reservoir.

it's not the booster. booster problems will not make the pedal hit the floor without actually braking. booster problems can only overassist (highly unlikely and nearly impossible) making the pedal hit the floor and you come to a screeching stop or underassist making it harder to press the pedal.

I'd put money on it being the master cylinder. even if they just needed to be bled, pumping 3-5 times should bring normal pressure back. any more than that and you've got more than just bubble problems.

If you can bleed them yourself, fine. don't pay a mech to do it.

[Gary Palmer]

When you were coasting in neutral, were you doing so with the engine off? If you were, then the problem probably is that the car uses engine vacume to give assistance to the brakes. Their is a reservoir which holds enough reserve for one or two stops. After that, the brakes will still stop the car, but relatively speaking you have to stand on those brakes, to get them to stop the car. They will still work and they will stop the car, but you really have to press down on them really hard. It also will feel like the pedal is going to the floor, because the assist is used up.

[kamesama980]

Originally Posted by Gary Palmer

When you were coasting in neutral, were you doing so with the engine off? If you were, then the problem probably is that the car uses engine vacume to give assistance to the brakes. Their is a reservoir which holds enough reserve for one or two stops. After that, the brakes will still stop the car, but relatively speaking you have to stand on those brakes, to get them to stop the car. They will still work and they will stop the car, but you really have to press down on them really hard. It also will feel like the pedal is going to the floor, because the assist is used up.

nope. Since it happened the first time he pressed the brakes and after many presses he got some pressure. also note he tried it several times driving and parked with similar results.

[GasSavers_bobski]

Originally Posted by Gary Palmer

It also will feel like the pedal is going to the floor, because the assist is used up.

Maybe figuratively speaking, since you have to apply alot of force, but in all actuality, that pedal won't be anywhere near the floor. Without vacuum assist, you would need a hydraulic jack to put enough pressure on the pedal to get it to the floor... That is, unless you have a bad master cylinder, or a leak in the brake hydraulic system some place.
Oh, and most cars don't have a vacuum reservoir. The pedal pump or two you get is the booster using up the vacuum already present in the booster itself.

[GasSavers_BIBI]

I'm getting the master cylinder change this afternoon.

Maybe they will bleed the brake too, if needed, thx all for the info.

[GasSavers_bobski]

Replacing the master cylinder inevitably introduces air into the brake system. They'll bleed the brakes as part of the MC installation or else the brakes will feel spongey afterwards.