Brake Master Cylinder

[Blaine122300]

After reading my Haynes manual, I've come to the conclusion that my master cylinder is going kaputz. When I first push on the brake pedal, it is fine, then after I hit it again, it slowly goes to the floor. I have already bled the brakes to no avail. I figure since my baby is 11 years old, that a new master cylinder would be a good investment anyway. Does anyone have any tips or anything I should look out for when replacing my master cylinder? I figure that I will flush out my whole brake system and make sure the fluid is top notch.

Thanks in advance for any help.

Oh yeah, on the NAPA website, I looked and it said if the brake fluid got to the boiling point, it can create air in the system. Has anyone else heard of this? How easy/hard is it to boil your brake fluid?

Andy

 

[Opera House]

Place in a pan on the stove and simmer

I probably came as close to boiling it as anyone. My 92 had a transmission problem and it provided no engine braking. I came down Mt. Greylock, 8 miles without pull offs, and things were smoking by the end. Pads had big cracks. The rubber boots disintegrated on the front calipers, which I suggest you replace too. By this age they fill up with rust that you can never flush out. Rebuilt these were less than $12 at Autozone. Rear are about $8, so why even fool with them. I know, $12 makes you feel uneasy! Anyway, like I said, they got hot and I never felt anything like a bubble.

 

[JDraper]

It's possible to boil your brake fluid, but unlikely in the X. A lot of it has to with having disc vs. drum brakes, wheel cylinder design and fluid capacity. You are much more likely to boil the fluid in a drum brake than a disc brake because the drum brake doesn't allow for as much heat dissapation from the wheel cylinder. I have boiled it in an old Mustang with lousy drum brakes, but never in either of my X's, and that includes towing trailers.

 

[SteveVB]

Boiling possible

I have boiled mine- when my caliper stuck and just about caught on fire. After everything cooled down and I replaced the slide pins cleaned everything up I still had no pedal. Someone mentioned I could have boiled my fluid and to change out the fluid- did it and no problems getting a nice pedal.

If the fluid is old it may have a good amount of moisture in it which can cause it to boil sooner than the fluid rating- which should be over 350 degrees I think.

 

[Blaine122300]

Well, I replaced my master cylinder, and Woo Hoo!! Bled the brakes and everything works like new again. I just wish the master cylinder wasn't so damn expensive for what it is. Just a small metal pump. Cost me 170 bucks at NAPA. Seems like it should be cheaper. Oh well, at least I can stop now. Can you rebuild these pumps, or are they a lost cause once they go bad?

Andy

 

[Stover283]

master cylinder

I just bought a master cylinder for my 92 sport. I have yet to get motivated enough to change it. I have borrowed my brother-in-laws truck with the exploder is out of commision.
I think you can rebuild. Not sure though, when I was at advanced auto, they had a kit you could buy. They key to buying one of these if to get one that is remaunfactured. I paid about $80. But that includes $35 core change I have not gotten back yet.
Was it hard to change the master cylinder?

Michael

 

[Blaine122300]

Welcome to the site!!!

No it is very easy to swap it out. all you do is remove the break lines that are on the master cylinder, and cap them off with a plastic bag and a rubber band. then there are 2 studs that connect the master cylinder to the booster. the stud on the drivers side (Right side if standing at the front of the truck looking at the fire wall) has 2 bolts on it. the outer one holds a bracket that holds the brake lines. once you get these off, you just take it off. the electrical connector has to come off too. It is a typical connector. The magnet on the bottom of the resevoir has to come off too. This will just slide into the new resevoir. I bench bled my new cylinder, which involves some fittings and some tube and you just fill the resevoir and pump the cylinder till no bubbles come out. you put the tubes going from the brake line holes back into the hole on top of the resevoir. Once you get everything back on the truck, you just bleed your brakes, and call it good. When I was done, my brakes were like new again.

Andy