I bleed the brakes again to get rid of some residual air. There was air in the left rear caliper. The problem came back. Hit the pedal hard like in panic stop and the car keeps rolling for a for a second or two and the pedal sinks while applying pressure and then the car stop. Maybe dirt in ABS unit or something sticks in there?

I am going to take it back to the dealer for diagnostic for what it's worth. They want $100 for the diag only.

The interesting thing is the issue goes away after driving the car and excersizing the brakes a bit.

 

hi doz5...were u able to track down ur brake issue? i am experiencing something similar to my 95 accord ex. my problem is somewhat intermittent. like urs, my brakes get "soft" once in a while and the pedal slowly goes to the floor when i continue to step on it. if i pump the pedal a few times it gets stiff again. however, i've only observed this on extremely hot days and after the car has been running for a while (20 mins or so). also i've so far only noticed this on city driving and not on the highway.

my brake fluid went too low before this issue started, so i figured air may have gotten in the lines so i bled the system. but the problem came back yesterday (heat wave in cali). i dunno if it's worth bleeding the brake system again, or if a part needs replacement first. i'm strapped for cash right now so im trying to minimize the trial and error approach when it comes to part replacement

 

The pedal sinking slowly & smoothly is the classic symptom of a bad master cylinder. There were some other things going on with his brakes, tho.

But keep in mind that your '95 has a completely different ABS system than DOZ5's '99. Your ABS has its own reservoir & bleeder screw. Bleed your main brakes first. Then bleed the ABS. Make sure you have a hose on the ABS bleeder & don't open it hardly at all. Lotsa pressure in there, don't get hurt.

 

idol4232003, you potentially have a serious problem. It sounds like the MC seals are going bad. You should take care of it immediately.

Eventually, you will not be able to stop as the pedal will go to the floor. The fact that you also had a low fluid in the system indicates of a leak. Look for leaks around the car. Tubes, hoses, calipers, ABS if you have one, rubber hoses. Check the hoses for cracks.

Pedal goes to the floor and than you need to pump to get back pressure sound like an MC.

Ambient Heat should not play effect here as the calipers gets hotter than ambient and when they do, they heat up the fluid.

My issue was different than yours. The dealer was completely useless.

My problem is solved but I am still adjusting the system. I will post the outcome at later date once I have it adjusted.

 

Thanks for the reply. Does anyone have any idea on around how much replacing the master cylinder would cost at a shop (parts and labor)? I read through the helms manual and it seems a special tool (which i don't have) is needed when adjusting the pushrod clearance. i dunno how critical this clearance is, and if it can be done with regular tools instead

 

I just replaced mine, you don't need this tool. The pushrod is on the booster and the pedal. Not on the master cylinder. This tool is to determine the how far the pushrod sticks out so you have a good pedal / hight response. I have done my booster using a caliper to measure that distance.

If you know how to bleed your brakes already, this should not be a big effort. I think you need to bleed the ABS too on that year car.

You need to determine if this is really the MC first. You might want to take it to the dealer for diagnostics. About $100.

My guess is that when the car is on, if you hold the pedal with steady pressure you should see it sink.

If you are going to replace it yourself, make sure you buy PB-Blaster from autozone and spray the two pipe fittings. after a few minutes, tap the fittings with a mallet. Use a flare fitting wrench. If you don't know what that is ask when you are at the autozone store. Take extreme measure NOT to round the fittings.

Let us know what were the results.

 

The pushrod length is important. Carefully compare the length of the pushrod sticking out of the master cylinder; old vs. new. If they're EXACTLY the same length, you don't need the tool.

If they're different, you can make measurements of the difference and adjust the pushrod under the dash (pedal to booster). The idea is that the diaphragm inside the booster is in exactly the same position as it was with the old MC. The tool makes this a lot easier, & maybe you can rent the tool someplace?

 

Thanks for all the info everyone. I will order a new MC and try installing it myself. Btw, I can understand how an internal leak in the MC can affect the fluid pressure to the brake lines...but can anyone explain why I only seem to observe this issue on extremely hot days

 

Did you check all the tubes, calipers, flex hoses, ABS for leakes?

 

I can't explain the connection with hot days, but I saw exactly the same thing when the MC went out in my 95 Integra.