Leichardti

alrite guys, i came home from work today and was planning on taken the seven to my buddy's house and as i open the door i see a puddle of brake fluid right below my brake master cylinder. and so i popped the hood and there i see the brake fluid leaking from the bottom bolt of the brake master cylinder right in between the booster and the cylinder. can somebody help me out and break the bad news to me please. i'm hoping its just a brake master cylinder but i have a feeling you guys might tell me its the booster as well. has anyone had these symptoms before or can help me out and leave me in the right direction???

85 FB

The booster is a vacuum unit, no fluid goes into that thing. It is either the M/C or the line fitting that leads out from it.

Leichardti

oh okay thats good to know... just called the auto parts store they said it be $37.00. i'm not complaining. is there a way i can check whether i need a new booster??

Kentetsu

grab a master cylinder. check at www.rockauto.com for a decent price to compare with your local parts stores...

85 FB

If your booster went, your brake pedal would go to the floor. I had this happen with one car that I worked with. The master cylinder fluid level dropped low. I added in fluid and it didn't leak anymore. However, I had no brakes. I pushed the pedal all the way to the floor and nothing. Thankfully the rear brakes engaged via a cable or something as a backup device.

I believe if your booster went, your pedal would go all the way to the floor because it's not working right against the plunger piston for the M/C.

ChaosAura

Most of the time theres a rod that incase of booster failure, the pedal connects directly with the M/C.

I havn't looked at what is is on our cars, but I would guess it would be the same, as a failsafe.

Usually a dead booster just means a rock-hard pedal, and you need to stomp on it to get much force to the wheels.

85 FB

Actually, first the pedal went all the way to the floor, and then once it was pushed into the shop's parking lot, and had to get on the brake pedal some more times, it became rock hard.

I just got confused on whether it went rock hard (because of no vacuum) or it first goes to the floor and then becomes rock hard. It was a long time ago.

Dan_s_young

iTrader: (1)

First few pumps very easy and down to the floor is an indication of fluid leaking. Then it went really stiff, car was probally not running, no vacuum assist and you used all of the stored vacuum = hard pedal.

Replace the master cylinder if you can't visually see any sign of damaged lines. Normally M/C's don't fail just like that, but they will slowly peel away the paint on the brake booster indicating that it is time for replacement.

redbstd

If you replace the m/c pull it apart and check for rust. mine sat for 4 years and the brake fluid sucked a lot of water throgh a small crack in the hose. so if there is rust inside you might want to pull off your slave cylinder and check it for rust as well. This just happened to the guy i bought my car from, just thought i should say something.

13BstreetportFB

just to let you guys know i accidently made the thread with my buddies screename but anyways. i just removed my brake master cylinder and i was pumping the cylinder with a screw driver and i notice brake fluid was only coming out of the rear oulet not the fronts. so it seems that my brake master cylinder is broken. right??? oh yeah, my car is a 84 GS FYI.... with my brake cylinder removed from the booster is it okay for me to step on the brakes to test whether the booster is functioning properly??? or should i wait until i get a new brake master cylinder and then test to see if my booster works???

85 FB

Yeah, I think when the car was pushed into the lot, the engine wasn't running. Tho, why the engine wasn't running, I can't remember worth anything. Like I said, it was a long time ago and the events in my head are just the worst. I know how the vacuum depletes as you keep pressing the gas pedal. I just can't figure out why the engine wasn't running when it was pushed back into shop lot. However, after I filled the master cylinder up with fluid, it never leaked again. But, still had no brakes.

I'm going to stop trying to remember it. It's making my head hurt.

13Bstreetport, yeah it sounds failed. I'd go ahead and replace it. It's not that expensive and it's not that hard to bleed the system when you have a friend help you.

13BstreetportFB

is my brake booster broken??? the paint is peeling on my brake booster??? i know for sure my master cylinder is shot but is there a way how i can check whether the booster is broken too with the m/c removed???

redbstd

Just rplace the master cylinder and make sure you take out you slave cylinder and check it, nothing is going to **** you off more than to put your new m/c on to find your s/c is bad. The slave is way easy to get out too its right on top of the tranny should take like 2min.

85 FB

Last time I checked, the brakes don't have a slave cylinder.


Paint peeling on your booster? Fluid must've gotten on it. Brake fluid is very acidic.

If your booster failed, your pedal would be rock hard.

Some links to see if they'll help
https://www.rx7club.com/1st-generation-specific-1979-1985-18/brake-problem-608190/
https://www.rx7club.com/1st-generation-specific-1979-1985-18/engine-dies-soft-breaks-588286/

redbstd

opps though he was talking about clutch, wow dont i feel like an idiot

redbstd

yeah just replace the master. Yeah but you carb has a belt and you need to fill your blinker fluid or else you'll need to get a squeegy sharpener to fix it

85 FB

Don't forget to put winter air into your tires. Oh, and I can sell you a 4 Piece Lowering Kit for your car for $80. Comes complete with 4 nails and a hammer.

Dan_s_young

iTrader: (1)

No, it means that your master cylinder is leaking. The brake booster only is a vacuum seal and it doesn't have any fluid in it.

13BstreetportFB

is it true if brake fluid leaked into the booster i have to replace the booster too??? i asked a mechanic and thats what he told me.... is he just trying to ask for money or is this true???

13BstreetportFB

thanks guys for the help... ya when you mentioned slave i was like ??? wtf are you talking about??? but yeah i appreciate it guys. i'm gonna order a new master cylinder and put it in and see how it goes.... hopefully my pedal isn't rock hard... sorry one more question... would the pedal still be rock hard even with the M/C REMOVED??? or I shouldn't touch the brake pedal until i have the new M/C installed???

85 FB

It is possible for brake fluid to leak into the booster and eat away at the rubber inside it.

DwArF

Fluid isn't going to leak from the brake booster. You need to install your new master cylinder first and then see if your still experiencing issues with your brakes

85 FB

I didn't say it will leak FROM the booster, I said it's possible it could leak INTO the booster. There's a big rubber diaphram inside there which the engine's vacuum helps pull for the boost. If brake fluid gets in there it could definitely eat that rubber.

13BstreetportFB

in my situation. the fluid hasn't been leaking inside the booster for a long time... i just noticed the leak and i'm worried if the brake fluid entered the booster is it damaged for good???

85 FB

Hmm. Well, when you remove the M/C, get a good flashlight and see about peeking into the hole where the M/C plunger goes int. Stick your finger in there (if you can) to see if you feel any wetness.

However, I don't think you have to worry about brake fluid getting in there, but it still doesn't hurt to check just in case, y'know?