mal.hrs

I got a 95 civic LX. The brakes are dangerously inconsistent. 50% of the time they work 100% fine but 5% of the time they don't work at all. The faster I'm going the more likely they are to work, never had a complete failure at more than 10mph but sometimes at 20 they go to the floor before kicking in. They are least likely to work on a slight forward slope, like when exiting as parking lot, that 1 degree slope at 5mph... no brakes. cant tell you how many times I've almost rolled into traffic. The E brake works fine, thank god.

Since I got the car I have:
blead 3 wheels
replaced a wheel cylinder
blead all 4 wheels.
replaced a caliper
blead all wheels
replaced the master cylinder
flushed the system completely.

I see no leaks, I'm not loosing fluid from my reservoir, and on 2nd and 3rd bleed I found no air in the lines. But still my pedal goes to the floor.

Please help.

BrotatoChip

Does it have ABS? Maybe it is causing issues.

mal.hrs

It's doesn't have abs but the previous owner gutted it and may have pulled that too...

Cobra2411

Did you bench bleed the master before installing? Maybe trapped air?

And clarification, is there an ABS module plumbed into the system? Sounds like no, but if it's there, they can get air bound.

I'm willing to bet there's still air in the line somewhere. I would bench bleed the master again. You don't have to take it off, just disconnect the lines and loop lines into the master and pump the brakes till no air comes out. Then start at the right rear (farthest), then left rear, then right front, then left front and re-bleed the system. Lastly, make sure your drums are adjusted to a very slight drag.

If that fails and there's no ABS module then you either have a bad master or a bad proportioning valve. I know the master is new, but sometimes it happens.

mal.hrs

I took it to a shop and they did a "power bleed" which didn't help. I'm convinced it's the proportioning valve, especially since, when they go 90% out, it feels like the back passenger wheel is the only one doing anything. I haven't gotten around to it yet cause it seems like a pain in the ***. Any tips?

And to clarify, this model never had abs.

Cobra2411

I have to agree. The proportioning valve, which is really a metering valve, blocks flow to the calipers till a certain pressure is reached. This lets the rear brakes catch up and overcome the springs and such before the fronts work. Could be that it's sticking up.

The pedal going to the floor to me says air and I don't trust "new" parts and I've seen "power bleeders" fail when conventional methods worked. I helped a friend once who spent hours trying to get a pedal using a power bleeder and a reverse bleeder and it wasn't till I bled the master that it worked. I probably would put a rag under the master and have someone work the brakes and crack the lines to see if I hear any air coming out. Brake fluid eats paint, so be careful.

Is it going to the floor with no resistance? Or you press as hard as you can and the brakes don't work.

mal.hrs

I did bench bleed the master but I will give it another tester like you describe.

Sometimes I get no brakes sometimes I get full brakes, usually it doesn't start working till the last inch of two and that's when it's only one or two wheels breaking.

Cobra2411

Rear drums typically have less fluid that moves and they have to move farther, so when the brakes start to work at the last inch or two it's the rear brakes typically that are coming on. So likely you only have rear brakes during this time. If they're not adjusted right one may grab more than the other. I typically adjust them and spin the wheel at the same time till I hear a slight drag.

The fact the pedal goes to the floor, I'm assuming with little resistance, that tells me there's an internal bypass or leak. That makes me think the master cylinder, but the bias to the rear also makes me thing proportioning valve. Again, it's technically a metering valve designed to allow the rear brakes to start working before the front, so there's a spring loaded valve to the front that won't allow a significant amount of flow till enough pressure is built up.

Can you make it do it? Or is it totally random?

mal.hrs

I can't make it happen but it's not quite random. It comes and goes but it's most likely if I'm just rolling in first gear, or when going down hill.. but some days I'll have perfect brakes.

Joseph Vignolo

This may explain your problem. When you bled the brakes did you push the pedal all the way down to the floor? The way these master cylinders are designed if you push the pedal all the way to the floor during bleeding it will damage the front seal inside the master cylinder. When this happens the new master cylinder will cause the exact same symptoms as the old one did. The reason why the brakes are erratic is because sometimes the damaged seal works right and sometimes it doesn't. To fix the problem you will need to replace the master cylinder again, but this time put a block of wood under the pedal so it won't go all the way down to the floor. Then bleed it normally. This way you won't damage the seal in the new master cylinder and the brakes should work fine every time you stop.