My rear passenger brake line is making a hissing noise when I'm bleeding it. I assumed it was air. I've ran several small bottles (355 ml) through the system and it's still making this noise. Just wondering how much it should take to get it all out if that is indeed the problem. I recently upgraded my brake system: Integra front and rear discs/calipers, 40 40 prop, new flex lines, and 1" gsr mc/ booster... So my system was open for quite a while and got plenty of air in it I'm sure. Also the passenger rear was the last one to start spitting fluid, an other reason I suspect this being a problem with air in the line. Any ideas how much this should take? Cause I wanna buy more fluid and get it done but I don't wanna keep adding to the mess on my neighbors garage floor if air is not my problem.

 

How are you bleeding? Pumping the pedal or line suction or vacuum pump?

 

Pumping the pedal

 

And the noise is coming from I think the hard line under the car NOT the booster. Every search I do on here or google that contains "hiss" and "brakes" only brings up a leaky booster... Really annoying.

 

Are you hearing the noise under the car at the brake, hard line and not in the engine compartment? Just trying to localize it.

 

Not the engine compartment. It's most prominent from the rear passenger wheel well, bt sounds like it's from the brakes hard line and not the flex line or caliper.

 

Also the noise is only present during bleeding when that valve is open and fluid is coming out. No noise when bleeding the other calipers.

 

Is the pedal firm? Air in the system will give a soft, nonfirm pedal.

 

Well the pedal was really firm, then as I bled all the brakes it loosened up to normal pressure. And when I started the process over again (to be sure all the air was out) it started making that noise and got heavy again.

 

Bump for more opinions.

 

I think the noise was merely fluid passing through the line. It sounded like a water (drinking) fountain. The other rear brake made the same noise, only less severe. So I ran another bottle through the system just to be sure and drove it anyway. Stops way better than my original system. Is the ebrake usually real heavy after converting to rear disk?