Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Suspension, brake, and hydraulic/electric steering discussion.
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sheistybikey
Posts: 15
Joined: Mon Apr 10, 2023 7:08 pm

Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Post by sheistybikey »

Hey so I've got a 2014 caprice ppv making a air leak sound when the brakes are depressed. Brakes still function great, the hissing will go on seemingly forever. The issue doesn't seem critical but id like to address it obviously. At the very least its annoying. so anyways my questions are this.

-do I need to bleed the brakes to replace the brake booster?
-has anyone here done this before? I haven't found a single thread about it
-is there any documented procedure for this or am i just going to have to wing it?
-any tips and tricks regarding the booster or how to approach the issue?

If I have to bleed the brakes I'm probably going to have to take it in to the dealer as I don't have the tools or patients for bleeding the brakes on a car (I'm a motorcycle mechanic). I'm hoping I can just take some parts off and replace them but I've never owned a car with a brake booster and I'm not sure exactly how it functions in this car. Anyways i thought it would be nice if there was a thread discussing the brake booster because it does not exist on this forum yet. so any info or diagrams or tips anyone has on the subject please drop them here so we can accumulate more info regarding the brake booster system.

thanks for reading guys
s/c'd cav
Posts: 1424
Joined: Mon May 30, 2016 3:12 am
Location: PHOENIX AZ

Re: Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Post by s/c'd cav »

can you hear the hissing over the radio ? if so then yes the booster is likely bad

no you dont have to bleed the brakes to do the booster , but the booster isnt that easy to change for as simple as it is , you have to play rubber man to get up under the dash
Sanford
Posts: 368
Joined: Mon Dec 12, 2016 9:38 pm
Location: Texas Gulf Coast

Re: Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Post by Sanford »

Had to take a quick peek to refresh my old brain. It looks like the master cylinder will need to come off as the lines are a larger diameter that the old cars of the 80’s. Not a lot of flexibility due to the size and location of the lines. Not much room where the booster is at. Looks like the plastic cowl will need to come out for some extra maneuvering room. Will need a long extension and a flex joint to get to the firewall bolts. Probably best to remove the knee bag.

Decided to take a look in the FSM. They show removing the master cylinder and the wiper motor/linkage. The rest of removal is pretty straightforward. At least they didn’t show the front cradle being removed.
shr3ddymurphy
Posts: 11
Joined: Mon Apr 24, 2023 2:41 pm

Re: Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Post by shr3ddymurphy »

Hey Sheistybikey,

Any updates on your fix? I’m dealing with a hissing (and even slight whistle) noise coming from the steering column area it seems. Also noticed recently the brake pedal depresses itself like its assisting me, which im not a fan of. All this started maybe a week ago.

From the responses it looks like the process is pretty involved. Trying to stay under a few hundred dollars if I end up having to take the car in. Any others that have gone through this feel free to respond.
s/c'd cav
Posts: 1424
Joined: Mon May 30, 2016 3:12 am
Location: PHOENIX AZ

Re: Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Post by s/c'd cav »

the brake booster alone will eat up 250.00 11-13 or 322.00 for the 14-17 , not sure what shop labor is in your area but a couple hours will easily go over your limit
zaprice01
Posts: 1
Joined: Wed May 22, 2024 10:37 am

Re: Brakes make hissing / air leak sound when pressed , possibly bad break booster?

Post by zaprice01 »

Hey all,

Having the same issue. My car has been doing it for about 10 months or 12000ish miles. I have a 14 PPV as well. Does anyone know how long this can go until the brakes no longer function as they should? Just want to make sure that I dont lose my brakes on the highway one day lol.

Thanks!
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