Brakes I Hear Air When I Push On The Brakes.

James.Little · May 3, 2014

When I hit the brakes, where if its a tap or if I slam on them, I hear air. I inspected the vacuum line that goes to the brake booster, I didn't find any holes. Also, I noticed around the master cylinder reservoir there is just brake fluid caked around it and every so often I have to add fluid. This go around, when I got low on fluid, I filled her up and I did not notice an improvement on braking power, like I normally do. Do you guys have any idea what is wrong? Is the master cylinder going bad?

jAEded · May 3, 2014

If your car is running, but parked, do you hear the same sound when you press on the brakes?

mikestang63 · May 3, 2014

most likely the seals on the M/C piston are worn and leaking out the back. AM sells a new Ford unit for about the same price as remans. Make sure you bench bleed the new unit prior to install.

dnbonds · May 3, 2014

I had the exact same problem and I got a new MC from AutoZone. I was also putting brand new rotors on and I found the leak. It was on my passenger side brake line that wasn't tight enough. I returned the MC since it fixed all of my problems.

I would clean off the MC and check it in a day or two to see if it is the MC and not a Brake line

James.Little · May 3, 2014

jAEded said:
If your car is running, but parked, do you hear the same sound when you press on the brakes?

Yes I do.

Also thanks for the responses guys. I will clean off the MC and see what see looks like in a day or two. Also, if I pump the brakes when coming to a stop I get more stopping power. So that means something right?

James.Little · May 3, 2014

dnbonds said:
I had the exact same problem and I got a new MC from AutoZone. I was also putting brand new rotors on and I found the leak. It was on my passenger side brake line that wasn't tight enough. I returned the MC since it fixed all of my problems.

I would clean off the MC and check it in a day or two to see if it is the MC and not a Brake line

All you had to do was tighten the brake line?

dnbonds · May 3, 2014

Sorry, let me correct myself lol. A friend of mine was installing the new rotors right before we were going to install the MC and bleed the lines. All he said was he found the problem and we shouldn't have to install the MC. I suppose it was loose from when I took off the calipers to install new Brake pads. I installed them 5 months prior to the problem though. Havnt had any issues since.

James.Little · May 4, 2014

Ah okay. I am totally going to key down this leak, thanks for the inspiration.

Shakerhood · May 4, 2014

Usually when you hear that rush of air sound it is the Brake Booster that is failing.

dnbonds · May 5, 2014

I had that air sound when my brake lines were leaking. Once it was fixed the air went away

Mustang5L5 · May 5, 2014

James.Little said:
Also, if I pump the brakes when coming to a stop I get more stopping power. So that means something right?

Yes, that can mean a few things.

I bet your MC is garbage to be honest. Sounds like it's leaking externally and probably internally. The rush of air sound is more than likely a booster leak. A common failure for the MC is the piston bore, and it tends to leak out the rear of the MC into the booster degrading the rubber seals. Check the front face of the booster UNDER the MC. if the paint is bubbling or it looks rusted up here, then this is prob the issue.

You shouldn't be adding fluid very often. Even if you've fully worn out the pads and shoes, the fluid shouldnt drop to the point where you need to add regularly. You shouldn't have to add ANY fluid. You have a leak.

Unbolt the MC by the 2 nuts and gently pull it away from the booster. Is the backside bore wet with fluid? Do you see rusted, blubbled paint on the booster?

Without insecting the rest of the brake system, i would venture to say the inner piston seal is failing on the MC. You may have to replace it, and the booster as well if the fluid has broken down the rubber diaphram.

89oem · May 5, 2014

^^ yep, so even when you wipe it down look for the source... if you have clumped old fluid around the MC unless you're pouring fluid like its your 3rd martini its leaking...

James.Little · May 6, 2014

Thanks for the suggestions, I hope the booster is failing, that sounds expensive. Also, when coming out of work the other day I noticed a small puddle under the car. I thought, that can't be good. I looked and this is what I found.

James.Little · May 6, 2014

I haven't done much digging, because I don't really have the time, but I am guessing I found part of the problem.

Mustang5L5 · May 6, 2014

That looks like your trans output seal is leaking...

The brake line does run through that area..so you'll want to check it out

James.Little · May 6, 2014

Mustang5L5 said:
That looks like your trans output seal is leaking...

The brake line does run through that area..so you'll want to check it out

Awesome, looks like I have some work to do this summer. This is why I am going to buy another daily driver, so when this happens I don't have much to worry about. Is there a temporary fix for this? Like just keep topping off the fluid until I finish with finals?

mikestang63 · May 6, 2014

What most likely happened - hope that it is this and not the bushing- is the rubber tail shaft seal is worn or cracked. It's a $5 piece. You'll need to remove the driveshaft, and then carefully with a hook or small screwdriver pull the old seal out. If its the bushing, then the whole tail housing needs to come off. Before you take out the drieveshaft, try and measure or feel the amount of play when you wobble the drive shaft. It shouldn't be more than an 1/8 to 1/4 of an inch IMO. If it is, chances are the bushing is worn.

You are going to keep pissing out fluid until its fixed. Stay on top of the fluid level as that is an easy way to fry an AOD.

James.Little · May 6, 2014

yeah ill keep an eye on it. Also, i have a T5

Mustang5L5 · May 6, 2014

Same deal...low fluid in a T-5 can score the mainshaft and cause the trans to whine like a bitch. Only way to repair is replace the mainshaft....

so stay on top of keeping the level of fluid full.

89oem · May 6, 2014

can you keep mileage down till then?

Brakes I Hear Air When I Push On The Brakes.

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