Hello,

I just bought a 92 honda accord and the brake master cylinder is going out, we think. The brakes will work sometimes but the pedal will give away and it will be all the way to the floor. Anyways, is it pretty easy to replace it? Does anyone have any type of instructions on how to replace it. Any information would be helpful. Thank you.

Melissa

 

Chilton, Helms Manuals...are your friend.

 

:elete double post on accident::

 

There should be instructions inside the box when you get it. And, it sounds like it's the source of your problem.

I recommend bleeding the master off the car to remove air pockets from inside the cylinder. ( When on the car, the pedal doesn't push the pistons all the way forward so you can't get all the air out that way ).

Fill the master cylinder resevoir with brake fluid and use a screwdriver or something to push the piston all the way forward. Before you release the piston, cover the holes in the cylinder with your fingers to prevent air from entering the cylinder when you release the piston. Then release the piston. This causes fluid to go from the resevoir down into the cylinder instead of air returning back through those holes.

Repeat this process until no air comes out the holes. Once you do this, keep your fingers on the holes to keep the fluid from coming out. You don't want the master cylinder to lose its fluid once you have bled it this way or else it'll fill with air again.

If you have the right size rubber plugs, use them so you dont have to hold your fingers over the holes. Make sure you replace the rubber seal for the booster where the pushrod goes through, if it came with a new seal. If you have a new one, make sure you remove the old one, dont double them up.

Put the master onto the studs on the booster. Unplug or remove a finger over one of the holes and screw the brake line fitting into the hole. It only has to be finger tight at this point. Repeat for the other hole ( if it has more than one, I'm assuming it has two ). Hopefully you havent let the master gravity bleed itself dry as you were installing it. If you do, you have to remove it and bench bleed it again to remove the air.

Some people dont, but I bleed all four brakes after doing a master cylinder.

* If you install a new master it's ok to push the pedal all the way to the floor as you bleed the brakes. If you bleed brakes with an old master cylinder, dont push the pedal more than about half way. Brake fluid contamination causes corrosion on the farther portion of the inside of the cylinder because the piston never contacts it ( the pedal normally never goes more than about half way down ). This corrosion will damage the piston seal as the piston moves past it causing the master to need replacment. Just a bit of advice learned through experience.

The new master should come with complete instructions, if I ramble too much to make sense of.

 

Thank you for the information. We will definatly try that.

Melissa

 

Foot, sorry to awaken this post but just had a question.

While bench bleeding, I fully understand to keep the resevoir full and push the piston in, and plug the 2 holes before releasing it.

However, how can I make sure all of the air has been purged out of the cylinder? Do I need to attach some clear tubing? How do I go about attaching the tubing tightly to those holes? Or perhaps is there another way?

Thanks in advance.

 

I wouldn't understand why people don't. You just let air into the system by disconnecting the brake lines. Duh...

I've replaced the master cylinder on my 93 civic twice since I've had it. I just did it like a month ago. Working great.

 

Kragen sells a kit with plastic plugs to plug the 2 holes in the master cylinder when you are bench bleeding it off the car before installing it on the car.

 

When bench bleeding......I just held it against my body, ready to plug the holes, pushed the plunger against my work bench, plugged the holes and released the plunger. Make sure you have a plastic bag around you or something because you WILL get break fluid on you. I ended up a little messy but worth the effort and money not to buy a stupid kit. If you bench bleed it thoroughly, you shouldn't have to worry about a couple of bubbles. They will work themselves out with a good system bleeding. A good time to change your brake fuid. Just keep bleeding each caliper until you see new fluid in the tubing. You must bleed the brake system per manual instructions. I think its LF, RR, RF, LR. NOT POSSITIVE. I bought a set of speed bleeders to make the process sooooo much easier. You can do it by yourelf in about half the time.