Hissing/whistling sound when not braking

[bail]

From time to time i can hear hissing or whistling sound coming from the left side of the car but when i hit the breaks it will stop. But everytime i hit the brakes hard, i can hear some noise. I also noticed my break fluid keeps on decreasing with no visible leaks. ABS light is also on. What could be the main problem in my braking system? Corolla 1.6gli 1997 model 118k mileage

[mina_nuka]

From time to time i can hear hissing or whistling sound coming from the left side of the car but when i hit the breaks it will stop. But everytime i hit the brakes hard, i can hear some noise. I also noticed my break fluid keeps on decreasing with no visible leaks. ABS light is also on. What could be the main problem in my braking system? Corolla 1.6gli 1997 model 118k mileage

You have a leaking BRAKE vacuum booster. Replacement is necessary

[bail]

Is the labor expensive? How about the replacement parts?

[mxmitsu419]

From time to time i can hear hissing or whistling sound coming from the left side of the car but when i hit the breaks it will stop. But everytime i hit the brakes hard, i can hear some noise. I also noticed my break fluid keeps on decreasing with no visible leaks. ABS light is also on. What could be the main problem in my braking system? Corolla 1.6gli 1997 model 118k mileage

Check your piston brake bro! it also happened to me... 500 lang repair sa Evangelista...

[miked]

From time to time i can hear hissing or whistling sound coming from the left side of the car but when i hit the breaks it will stop. But everytime i hit the brakes hard, i can hear some noise. I also noticed my break fluid keeps on decreasing with no visible leaks. ABS light is also on. What could be the main problem in my braking system? Corolla 1.6gli 1997 model 118k mileage

if there are no visible leaks at the four corners then check for leaks at the proportioning valve. if there's no leak e malamang sa may master cylinder. it is leaking fluid into the brake vacuum booster ("hydrovac")

[Lew_Alcindor]

Is the labor expensive? How about the replacement parts?

for the hydrovac, you opt for a surplus part.
for brake master, use original repair kit or original replacement parts (kung papalitan buong assembly)
this is a simple job for experience mechanic. should not cost a leg.