brake issue. HELP!

1wickedA70

1wickedA70

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i recently bought a 91 shell and transferred over my drivetrain from my 87. while swapping my coilovers a broke a brake line. so i replaced it and i bled the brake system. the brakes were firm with the car off, and it felt as if there were no air in the system. but when i started the car the brake pedal would feel very soft and hit touch the floor almost instantly. this sounded like a brake master cylinder problem, so i replaced it with a new one and still the same problem. so now i am thinking maybe its a bad booster? i unplugged a vacuum line that attached to the check valve and plugged it with my finger and the brakes were instantly firmer and felt better when i pumped it. Does this mean my brake booster is bad? or check valve? idk what the symptoms for a bad brake booster are..PLEASE HELP! i want to get this car on the road already :(
 
IBoughtASupra

IBoughtASupra

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Mar 10, 2009
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Take out the check valve, you should only be able to blow air through it in one direction.

Two, a bad booster would make the pedal difficult to press.

Maybe you bled it wrong.
 
barkz

barkz

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^ depending on if it has ABS. You need to start furthest from ABS block ie: Driver Rear, Pass Rear, Driver Front, Pass Front.
rebleed, adjust pushrod from booster to master as remans have different tolerances, hence the adjustment nut on the rod. boosters rarely go bad
 
hvyman

hvyman

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Doesn't matter. Rr is the farthest from the master. Fluid goes from te master to the abs to the caliper.

When abs is not activated the actuatOr is in the open position. Also when it fails it remains in the open position for safety.
 
1wickedA70

1wickedA70

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i bled the system again in the correct order. bled each caliper 4 times and still nothing! im hearing a hissing noise when i pump the brake when the car is off..sounds like air. does that mean my booster is holding isn't air pressure or something? The person that had the car before me never had any issues with the brakes. i really doubt it is the booster. but i already changed the master cylinder, and the check valve is working. so that just leaves the booster i guess....unless i still have air in the system. i bled it well today, but im still hearing the hissing noise when i pump the brake. my brother's supra doesn't make that noise when i press his brakes. ???
 
1wickedA70

1wickedA70

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no i didnt bench bleed it. i just put it on and bled the brakes. i changed master cylinders before without bench bleeding. defective master cylinder could be a possibility. but does that happen often? the brakes literally feel the same as before i changed the cylinder :(
 
barkz

barkz

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get a new one. should be under warranty(i would hope). then bench bleed, cross fingers, try again, report findings
 
1wickedA70

1wickedA70

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update. i noticed when i pump the brakes i see the fluid inside the brake cylinder moving. and the hissing noise might be air in the master cylinder itself. ill take it out and bench bleed it, then put it back on and see what happens. also that could of been the problem with my previous cylinder because there was no fluid what so ever in the system, and i remember hitting the brakes a few times while the car was sitting in my driveway. its starting to make sense since the previous owner of the car never had a brake issue. most likely i have to bench bleed the cylinder. ill let you guys know in a few days!
 
OneJArpus

OneJArpus

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Jul 1, 2005
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I had the same thing happen to me. MASTER CYLINDER! I went through 7 REMAN masters and they all did the same. I got 1 used master and it fixed the problem!


Seems like they don't know how to rebuild our master cylinder properly.
 
1wickedA70

1wickedA70

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OneJArpus;1781902 said:
I had the same thing happen to me. MASTER CYLINDER! I went through 7 REMAN masters and they all did the same. I got 1 used master and it fixed the problem!


Seems like they don't know how to rebuild our master cylinder properly.
Click to expand...

wow! i didn't know it was common that the reman cylinders were defective. i have hope now! lol ill get another one ASAP and update you guys some time next week. no time to work on it :(
 
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