hi guys. i'm new to the forum and i've been searching for an answer but havent found anything.

i need to replace the master brake cylinder on my 4-door '94 accord with ABS because my pedal is sinking when stopped at a light. I have swapped out a master cylinder on a car without ABS before, but never on a car with ABS. does anyone know if the process is the same? Or do i need to have a professional shop install the master cylinder since it is connected to the ABS system?

the ABS light has been on since i purchased the car, and the ABS currently doesnt work. when i start the car, the light is off. but as soon as i put it in drive and roll forward, the ABS light comes on. I don't care about getting the ABS to work, i just want to make sure my normal brake function isnt affected by it. thanks for the help.

 

You can replace Master Cylinder w/o worrying about ABS system. Some bench bleed the MC, but I've always bled after installing w/o problems.

A flare tubing wrench (10mm) is helpful to avoid rounding the tubing nuts connecting to the MC. They can be very tight and an open-end wrench may round the off rather than turn them. Harbor Freight has a set of flare tubing wrenches for about $5 last I checked.

I recently switched to vacuum bleeding and like that procedure to bleed the brakes w/o pumping and a helper.

If you want to repair the ABS system, get the fault codes . See DIY forum for obd1 codes, ABS is same except ABS light will flash codes. Forum will provide guidance on repair.

good luck

 

i'm glad to hear that. i've been putting off the swap for a while now. thanks for your help. i guess ill take a look into the ABS too since its easy to read codes

 

Also, look in the DIY section for a post (by me) about bleeding the ABS system.

 

So i finally got around to installing the master cylinder (snow storms in NY kept pushing me back). However, the car has almost no stopping power. It feels like there's no pressure because I can slam on the brakes and the car will gradually slow down. I bench bled the cylinder before installing, and bled the fittings at the cylinder, but I have bled the brake lines yet. I will do that tomorrow.

Here's my concern that I was hoping to get some feedback on. The instructions that came with the cylinder say to bench bleed until there is no air coming out AND the piston cannot be pushed in more than 1/8". After about 10 minutes of pumping, I stopped seeing air come out, but the piston still went in as far as I would push it (1" according to the instructions). After another 15 minutes of pumping, I gave up. Could this be the reason I have no stopping power? Should I have continued, or was I doing something wrong?

I did the bench bleeding using bleeder tubes that were submerged in the fluid in the reservoir. The strange thing is that the fluid level never went down much after I started bleeding. Probably less than 1/4" but I would thing the cylinder could hold more than that. I apreciate your feedback. Thanks guys.

 

I've never bothered w/ bench bleeding. Too messy and you still must bleed each brake line since air will enter when you separate brake lines from MC. Bleed each wheel thoroughly to remove all air. If you do this manually w/ help, it will take 10-15 cycles in my experience on the rears. Somewhat less on front.

good luck

 

Will bleeding the lines really make that much of an impact though? I'm sure it will help, but the fact that the braking power is so weak made me think it could be something else.

 

Is the pedal solid or mushy when you use the brakes?

 

pretty mushy. i'm pretty sure the pedal went down to the floor when i tried braking hard. guess it either needs to be air in the line or a damaged cylinder right?

 

Air in the lines is my first thought.

A bad master cylinder usually gives a nice hard pedal but then slowly sinks to the floor when you're holding moderate pressure (long red light).