Brake hiss

[DallasTahoe]

So I thought I noticed this hiss when pushing on the brakes, usually I would only hear it when I hit the brakes hard and fast, but it started doing no matter how hard or fast I pushed them. Once I got home and pushed on the brakes it hissed the whole time I had them pushed down, and my truck was running a bit rough, I know that is usually from a vacuum leak, so once the truck was off for a few minutes I unplugged the vacuum line and it still had vacuum. Ive never had a booster or master cyl go bad on me so I don't know what to fix, Bad brake booster? Master cylinder? Help?!?


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[M1Gunner]

So I thought I noticed this hiss when pushing on the brakes, usually I would only hear it when I hit the brakes hard and fast, but it started doing no matter how hard or fast I pushed them. Once I got home and pushed on the brakes it hissed the whole time I had them pushed down, and my truck was running a bit rough, I know that is usually from a vacuum leak, so once the truck was off for a few minutes I unplugged the vacuum line and it still had vacuum. Ive never had a booster or master cyl go bad on me so I don't know what to fix, Bad brake booster? Master cylinder? Help?!?


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Sounds like it's time for a new brake booster. Unfortunately it may also be time for a new master cylinder too. When the brake booster diaphragm fails it's because the master cylinder is leaking brake fluid into the booster and it deteriorates the diaphragm.

Unbolt the master cylinder. And gently pull it free from the booster. Once you have enough room, check inside the booster for brake fluid. Sometimes you'll already have signs of fluid leaking which include the paint on the booster peeling and flaking off.

Start there and get back with us! Good luck!

 

[DallasTahoe]

Sounds like it's time for a new brake booster. Unfortunately it may also be time for a new master cylinder too. When the brake booster diaphragm fails it's because the master cylinder is leaking brake fluid into the booster and it deteriorates the diaphragm.

Unbolt the master cylinder. And gently pull it free from the booster. Once you have enough room, check inside the booster for brake fluid. Sometimes you'll already have signs of fluid leaking which include the paint on the booster peeling and flaking off.

Start there and get back with us! Good luck!

Noooooooooooooooooooooooooooooooo!!!!! Ugh fml


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[M1Gunner]

another way to check the booster though is to push the brake pedal in while the engine is running then turn the engine off with the brake pedal still depressed. If the brake pedal doesn't travel after about 30 seconds then the booster is still air tight.

Or...

let the engine run for a couple minutes then turn it off and press the brake pedal a few times and if the pedal does not go down as far after each time then the booster is air tight.

 

[DallasTahoe]

another way to check the booster though is to push the brake pedal in while the engine is running then turn the engine off with the brake pedal still depressed. If the brake pedal doesn't travel after about 30 seconds then the booster is still air tight.

Or...

let the engine run for a couple minutes then turn it off and press the brake pedal a few times and if the pedal does not go down as far after each time then the booster is air tight.

Ill try that in a little while. I really didn't notice any change in the brakes, the hiss is what's got me, sounds like a vacuum leak as soon as I touch the brakes


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[DallasTahoe]

another way to check the booster though is to push the brake pedal in while the engine is running then turn the engine off with the brake pedal still depressed. If the brake pedal doesn't travel after about 30 seconds then the booster is still air tight.

Or...

let the engine run for a couple minutes then turn it off and press the brake pedal a few times and if the pedal does not go down as far after each time then the booster is air tight.

Thanks for the help man it was the booster, now she's gotten better braking, no telling how long it had been leaking before I was actually able to hear it


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