Brake pedal hissing

[David Vandercook]

Hey y'all,
My brake pedal started hissing the other day. It only did it occasionally but it happens more now. I can make it go away by giving the pedal a light tap, but it comes back before too long. I'm assuming its a leaky seal somewhere, but I don't know how to go about finding it. It sounds like it's coming from the brake pedal itself though, not the brake booster in the engine. Where should I look for leaks, and what do I need to do to stop the hissing? Thanks

 

[Dodge 1500 4X4]

Its leaking through the brake booster, that's the vacuum noise you hear, if it's stopping ok live with it.

 

[David Vandercook]

Well, it's getting worse. Would a new brake booster fix it?

 

[1999 White C5 Coupe]

Well, it's getting worse. Would a new brake booster fix it?

Yes - a new brake booster would fix the issue.

The vacuum bellows inside the current booster have a leak - which will only get worse. This is a safety issue and you could loose full vacuum brake assist unexpectedly.

Although you may be able to stop the vehicle, you would have to use considerable more pedal pressure and allow for longer stopping distances. Think driving on the expressway or downhill.

To ensure this issue is the brake booster, closely examine the vacuum line from the engine to the booster - and the plastic fitting on the booster that it connects to. Ensure there is no damaged hose, leak or loose connection.

 

[David Vandercook]

Thanks for the help, I'll do that

 

[Bob Bash]

I had that same issue on my 84 W100 last year and it was the booster . I was able to get a replacement from O'reilly's auto parts . It cost $120 and there is a core charge . Lifetime warranty . It was a bit of a pain to get to the 4 mounting nuts above the brake pedal and in my case the clutch pedal but very doable.