Q: Brakes hiss when I use them

asked by on October 29, 2015

The ABS light has been on for a few weeks in my 2007 Camry V6 that I have driven for around 104,000 miles, and there's a hissing sound when I apply the brakes. I had my brakes and rotors changed last week by my mechanic friend, and I still was having the same issues. Today, the brakes lost power and it's like having old school manual brakes. Help, please.

Well, it sounds like you may have a vacuum leak coming from the brake booster. I definitely recommend you do not drive the vehicle until you have an independent mechanic look over it, as this is a major safety concern. Typically when you will hear a hissing sound from applying the brakes, or if you hear the sound but the hissing noise goes away when the brakes are applied, it is a very good indication that the diaphragm in the brake booster is failing. The diaphragm allows air to escape the system and thus makes it harder to apply the brake pedal when it is failing. In addition to this, a bad or failing brake booster can be a symptom of another hidden problem, which is known as a leaking master cylinder. Now these two issues don’t always go hand in hand, but they often can and a certified technician will be able to determine if the master cylinder is leaking by separating the master cylinder from the vacuum brake booster and inspecting the cavity in the vacuum brake booster for signs of brake fluid. Brake fluid can eat away at and break down the diaphragm inside the vacuum brake booster as well. Before a repair is attempted, a diagnostic scanner is used to communicate with the ABS computer to determine if the warning light is related to this primary concern. If it is the case, the diagnostic scanner is used to clear the code from the computer and you can have the power brake booster is replaced. If that is not the case, further diagnoses will be needed to identify the problem.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Head gasket or engine rebuild.

Hi Chris. Thanks for contacting us today. The problem with repairing a head gasket issue is that it's impossible to know what other damage has occurred inside the motor. Quite often a head gasket becomes damaged due to overheating issues....

Car is running hot

Hello. There are multiple things that would explain why your car is running hot. The most likely cause would be that the water pump has gone bad and is not circulating the coolant into the car properly. It is also...

Slight misfire

Hi there. From the description you have given, the slight misfire could be caused by worn or fouled spark plugs. The slight misfire is apparently not being recognized by the vehicle's computer (the check engine light would flash and then...

Related articles

How to Use a Prius as a Generator
Being Being without electricity due to natural disaster or repair work being performed on electric lines in your region is at best an inconvenience and at worst life-threatening, especially when you depend on electricity for essentials like heat in the...
What Are Brake Pads Made of?
Brake Brake pads are an essential component of the braking system of your car. Every time you press the brake pedal, this force translates by way of a hydraulic system to the caliper. This caliper in turn pushes the brake...
Symptoms of a Bad or Failing Parking Brake Drum
If your car's parking brakes don't hold or just work poorly overall, you may need to replace the parking brake drum.