Brake problems with '92 Accord

[mudd375]

I recently had my rear brake fixed. (Brake lines replaced, pads replaced and reset) They work fine most of the time, but it seems if I drive more than 25 miles in a day, they start to get soft again. By soft, I mean I have to press the pedal all the way to the floor to get any reaction. This only occurs after driving for a while though, most of the time they are fine. I took it back to the shop I had it fixed at and they couldn't find a problem. Is there something else I can do? Any suggestions would be great. Thanks.

[ProMan]

It's your master cylinder.

[jeffcoslacker]

That or they are adjusted too tight, heating up and vaporizing the fluid in the wheel cylinders and lines, which can be quite dangerous, they will fail completely at some point.

Stop the car once you feel it happening and see if there is any excessive heat radiating from the rear wheels or backing plates...I assume you have drum rear, they should never feel too hot with normal use.

High moisture content in the fluid can do this too, but if they replaced all that you should have good fluid in there.

Usually with a bad master cyinder problem you can quickly stroke the pedal and it will build up, but fall as you hold it when stopped. Ever try that?

I assume the brake warning light has not been on even when the pedal is low?

[mudd375]

Thanks, they had suggested the second time I took it in that it might be the master cylinder. Any idea what a fair price would be on that? And Yes, actually my brake light goes on intermittently, and though I told them about that and asked about it, apparently they didn't think it was a big deal. Also, I had both my rear wheel cylinders replaced when I took it in. Does that matter? Still the master cylinder? Thanks again for your help.

[inafogg]

Hello, was this a problem before the repairs were done.it is possibly a master going bad but if this is a new problem i'd make sure all the air was bleed out
Good Luck!!

[jeffcoslacker]

When does the light come on? Under braking or randomly?

If the master cylinder was marginal to begin with, bottoming during bleeding may have made it go bad. Happens sometimes. That's why you aren't supposed to hit bottom with them.

RR, LF, LR, RF is the proper bleeding sequence for split diagonal braking systems. A different sequence can have you just chasing air all through the system.

Who did the work? Some places still don't understand if you work on the rear in a split system, you have to bleed the front as well...

A brake warning light with a full reservoir is indicating an imbalance in pressures in the two sides of the hydraulic system...leakage or air contamination is indicated.

I wonder about a shop that tells you that the brake warning light is not important.

Air expands as it's heated...any air in lines will increase in size as the fluid warms up and create even longer pedal travel with less effect....

[mudd375]

Definitely a problem before I brought the car in, which is the reason I brought it in in the first place. My roomate has had problems with this shop before, it turns out... so I do question their opinion (wish I'd have known before, as now my exhaust is loud too.. coincidentally the day after I picked it up) It is always random when the brake light comes on. Sometimes I start the car and it's on, sometimes it just goes on after driving.. there is no real way to tell, so I assumed it was just an electrical problem. I'm not sure if they checked the front end, as I had to replace a front ball joint as well (front passenger side). My receipt says "check braking system, remove wheels, inspect system and advise" "replace left and right rear wheel cylinder and bleed brakes" "replace shoes turn drums clean lube and adjust" "replace brake line as needed and bleed brakes" "adjust front and rear end"

I definitely need this problem fixed, but do I bring it back to the questionable shop or do I take it somewhere more reputable? If it is a whole new job, I'd rather take it somewhere else, but if this is something that should have been taken care of when I paid for it the first time, I want the original shop to fix their mistake. Thanks.

[jeffcoslacker]

I'd take it back to the original shop and give them the chance to get it right. There's no reason someone should have that much work done and still have marginal brakes.

They didn't fix the original problem, so they should cut you a break on labor if further repair is needed. If not, I'd stay away from there after this is resolved.

Did you ever determine if the pedal height will pump up and fall when held when it starts not acting right?

[inafogg]

the only prob with taking back is there gone to want to replace master cyl. first!!! but if you still have the problem after are they going to suggest something else or will they begin to diagnose the problem?????

[mudd375]

Originally Posted by jeffcoslacker

Did you ever determine if the pedal height will pump up and fall when held when it starts not acting right?

Sorry, not sure what you mean by that. You had said in a previous response "Usually with a bad master cyinder problem you can quickly stroke the pedal and it will build up, but fall as you hold it when stopped. Ever try that?

This I've noticed happens relitively frequently, if I'm stopped at a red light, especially a long red light. The longer I wait, the more I feel like I'm inching forward and have to press the brake pedal all the way to the floor. Just to see if my they worked at all, I drove down a hill in my neighborhood to see how responsive my brakes were, and again, I had to press them all the way to the floor, but when I REALLY stomped on them, they did actually skid the tires. I really appreciate your advice, guys, if theres any more information you need let me know. I'm not ready to let go of my Honda yet!

[jeffcoslacker]

That's what I meant, when you feel like the pedal is falling, put it in neutral and pump it a few times quickly and see if the pedal seems to get higher...that's a typically how a bad mater cylinder will act. Fluid ahead of the pistons is bypassing the piston seals slowly, so the pedal falls the longer you hold it...when you pump it, you replenish the fluid volume ahead of the pistons and the pedal gets higher, then begins to sink the longer you hold it.

In other words, the longer you hold the pedal down at the same height, the lower the pressure to the brakes, until the car begins to creep. Pushing it down harder might work, but stroking the pedal to get your pedal height back is preferable, because at some point you'll push harder and nothing will happen....then the master has failed completely...not a good feeling when sitting at a red light, even less when you are coming up to a stop and find you suddenly have no brakes. Remember to pump them to recover it, not push harder...pushing harder only forces fluid past the seals faster, and there's a limited amount there to do the work, once it's gone, it will take 5-6 full pumps of the pedal to recover any braking effect...by that time you've usually hit something...

It's likely you may have to replace it.