Hey guys. Car is a 91 CRX si all stock. Alternator is bad. Battery light comes on and off at times. When parked (car running) if you push the brake it will slowly go to the floor. If driving the pedal is very soft and will continue to push to the floor if you stay on it. If you pump the brakes it helps. Is this related to a bad alternator, dim lights, dim guage lights, and weak electrical power. The brakes are powered so I would think this might cause it. Or is this brake problem totally unrelated?

Thanks

 

sounds like your master cylindar going out...not alternator related.

 

 

absolutely not. youve got two issues.

replace the alternator.

replace the master cylinder.

 

ok so its a brake problem. I just bought the car and this is how it came so I cant tell if it just suddenly happened or when it happened.

Is it possible that the brakes may need to be bled or it is definately a master cylinder problem? Could it be a bad brake booster? I am not to familiar with all the parts of a braking system so i could be totally wrong.


Modified by TurboEM1 at 1:32 PM 5/18/2006

 

its an internal leak in the master cylinder seal. typical. replace it.

its not an issue of bleeding the brakes. it always helps, but its not your issue. youre going to have to bleed anyway once you put the new master cylinder on.

you should bench bleed the master cylinder too. look it up.

 

Just cirious. Would the fluid level be low or would there be fluid in the engine bay?


anyway thanks for the replies. I am searching now as we speak.

 

usually its just an internal leak around the master cylinder piston. no loss of fluid.

sometimes it does leak and dribble down the brake booster.

sometimes it actually enters the vacuum chamber of the brake booster and then enters the intake manifold and gets combusted out of the engine and tailpipe.

 

this might be helpful. you should get a helms, or at least an electronic copy.

 

last thing thanks so much for your help.

Car is a 91 crx si (4 wheel disk). What size is it? 7/8? Will any 7/8 non abs master cylinder work or will it have to be from a CRX Si.

Also i have a haynes. Not sure if tis as good though

 

7/8"

http://www.norcalcrx.org/tyson/brakepartslist.xls


dont listen to ppl telling you to "upgrade" your MC. just replace it with a working stock sized MC.

nothing is as good as a helms. all others are worthless.

 

I had the exact same symptoms (the brake symptoms) before I replaced my master cylinder.

I didn't lose any fluid, and there were no leaks. But the pedal would slowly sink if I kept steady pressure on it.

Replaced the master cylinder and completely solved the problem. Now the brake pedal is very firm.

It's pretty easy to do. I made sure to bench bleed the new MC, switched them out and bled all four corners. There was barely any air in the lines because I bench bled the MC first. Definately do that, unless you enjoy bleeding the brakes forever. lol

 

If you have someone pump the brake pedal & then hold hard pressure with their foot, you can watch the master cylinder fluid level go up & down. As they pump the brakes, the level will drop. As they hold heavy pressure on the pedal all the way to floor, you will see the fluid level rise again. It's lame you have to get a new one, but a master cylinder swap is very easy...

Bench bleed the new master cylinder as Tyson said, and only use a "flare-nut" wrench to disconnect the brake lines from the master clyinder. It's a cheap tool (similar to a regular open-ended wrench), but it can save you hundreds of dollars in brake line repairs. It keeps you from rounding off the brake line nuts...

 

good point.

dont even ATTEMPT to loosen any brake line with a regular 10mm wrench.

you MUST MUST MUST use a flarenut wrench. go to sears and buy one.

10mm, not 3/8".

 

While we are on the subject, here's how I bench bled my new MC.

 

They even sell them at Pep Boys. I bought the 10mm/12mm combo with one size at either end...