I just bled the brakes and got them working fine. No abnormal sounds at all. Later, I turn on the car for a moment, turn it off, and now the brakes are making an airy sound when I let off the brakes. There is no sound when depressing the brakes. The sound kinda sounds like gurgling, or maybe when you're sucking the straw from a cup of soda you just finished. The sound comes from around the master cylinder/brake booster area, but I'm not sure which component for sure since they are right next to each other.
I made sure there was no air in the master cylinder by cracking open a metal line and letting it weep fluid. I'm suspecting a brake booster vacuum leak. Has anyone had this problem before?
Noise when letting off brakes
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jesc
- Posts: 13
- Joined: Wed Mar 12, 2025 2:08 am
- Your car is a: 1978 Fiat 124 Spider
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jesc
- Posts: 13
- Joined: Wed Mar 12, 2025 2:08 am
- Your car is a: 1978 Fiat 124 Spider
Re: Noise when letting off brakes
I found fluid in the brake booster and a leak from the master cylinder where the parts connect. Looks like I'll be replacing those two.
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18Fiatsandcounting
- Posts: 3875
- Joined: Fri Mar 15, 2019 11:23 pm
- Your car is a: 1969 and 1971 124 spiders
- Location: San Francisco Bay Area
Re: Noise when letting off brakes
Fluid in the brake booster comes from a leaking rear seal on the master cylinder, but given that you heard some "air" sounds from the booster earlier, I think your assessment is right that both the MC and the booster need to be replaced.
One suggestion: Don't try to remove the brake line nuts from the MC (2 front and one rear) with a normal 10mm open-ended wrench or vise-grip pliers. You'll just damage the nut. Get yourself a good flare nut wrench. Most auto parts stores should have them.
-Bryan
One suggestion: Don't try to remove the brake line nuts from the MC (2 front and one rear) with a normal 10mm open-ended wrench or vise-grip pliers. You'll just damage the nut. Get yourself a good flare nut wrench. Most auto parts stores should have them.
-Bryan