Clemens88

I have 82 rx-7 that i've been putting back together. I bled all the breaks front and rear they seem to work just fine, but there is a slow slow leak between my master cylinder and brake reservoir. Is there a way to fix this without replacing the whole thing? Also, when I was bleeding my breaks, I would pump the break for awhile then if I were to release the break it would make a weird sound like air leaking. Is this normal?

yodler

i also have an 82 and am currently working my brakes. my pedal is very soft and the brakes don't really hold at all right now. i bled the rears but haven't bled the fronts. i also hear what sounds like air coming from somewhere around the master cylinder or whatever is behind it - booster pump? i second the question - anyone know whether this is normal? sort of a whooshing sound as you press the brakes, coming from master cylinder area. thanks all.

orion84gsl

iTrader: (5)

Bleed front, then the rears. Replace your master cylinder if you think it's defective. It's cheap enough and too important to risk trying to fix it.

7SpringsMisfit

rebuilding the master cyl is pretty damn easy. but hey they are fairly cheap just to replace

Clemens88

Thanks I didn't know they were so cheap. If you have a stock master cylinder when you press the break all the way down does it make a hissing sound after you release it? Because I'm not even sure it the master cylinder. I did a soap and water test on it and couldn't find a leak.

orion84gsl

iTrader: (5)

There should be nothing making any noise when applying the brakes. Maybe some squeal from the pads, but otherwise you should just get smooth braking and pedal effort. A hissing is probably either air being sucked in or liquid being pushed out. Do it a few times in the driveway, if there is a puddle underneath, you have a leak. Or have a friend/sibling/parent come over and pump the brakes while you listen for this hissing sound, and find where it's coming from.

Clemens88

Ok it is coming from inside the power brake unit, and whenever I'm running the car you can hear it hissing, also the car stutters when you rev it up.

Kentetsu

Sounds like you need a new brake power booster. There is a diaphragm inside it that can become perforated and cause issues.

Also, when bleeding the brakes, bleed the brake farthest from the master cylinder first (passenger rear), then work your way closer from there.

Rx-7Doctor

iTrader: (13)

If the master has been leaking for a while then the fluid has gotten into the booster and has probably damaged it. Is the brake pedal very hard like it is not getting any vacuum assist to it?

Clemens88

Yah its pretty hard

yodler

can someone describe the difference in the feeling the brakes should have when the motor is running and when it is off? i am troubleshooting on two fronts right now - brakes and carb/fuel, so i can't keep the car on long enough to pump the brakes for feeling. when i pump them with the car off, the pedal is extremely soft. i'm just wondering when people say it will feel hard and soft whether they mean when the car's on or just generally. does the feeling change for people? thanks everyone.

gsl-se addict

iTrader: (3)

Take a look at the FSM, section 11, page 19.

http://foxed.ca/rx7manual/manuals/19...11)braking.pdf

This will tell you how to test your booster. There are 3 simple tests that you can do (no tools required). You can also test with a specialized tester (measures pressure, vacuum), but the simple test will do.

Re-Speed.com

iTrader: (3)

Exactly.

-billy

yodler

thanks addict

Clemens88

Thanks I'll try that test.

orion84gsl

iTrader: (5)

Oh yeah. Sorry guys, brain fart. I honestly did know that too. I have bled brakes before. Hmmmm

Clemens88

I can't do the test just yet, but can I rebuild my power brake unit and master cylinder? If I can where can I find a kit for a GSL?

gsl-se addict

iTrader: (3)

The master can be rebuilt. Check autozone, advanced auto, etc. May be better to get a rebuilt unit, though. Just depends on cost. For the booster, there are no kits that I know of. Probably need to get a new/rebuilt unit if it is bad.

Also, try www.rockauto.com. They have great prices and service if you can wait a few days for the parts. If you do buy there, search this forum for a discount code first. There is usually a valid discount code posted on here somewhere.

Kentetsu

One other thing to keep in mind. During normal braking, the piston in the MC normally only travels part of the distance that it is capable of traveling. So, when bleeding the brakes, it is a good idea to place a piece of 2x4 or something under the pedal to keep you from depressing the pedal beyond the normal operating range. The cylinder will usually develop a bit of a lip at the end of travel, so if you go beyond that point, then you can damage the seals on the piston and destroy a perfectly good master cylinder...

Clemens88

Thats good info, I wish I new it before I bled the breaks. The master cylinder seems to be fine though its not losing pressure or leaking.

trochoid

iTrader: (6)

There is a testing proceedure in the FSM for the booster, Sec. 11, p. 19. Run the first 3 tests and post the results. You probably won't have the gauges to do the pressure test. There is also a rebuild proceedure for the booster. I'd simply replace the unit instead.

If you're hearing air when the pedal is depressed. Check the vacuum line to the booster for leaks.