Air in Brake Fluid
Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
Air in Brake Fluid
Well, I had an incident the other day where the brakes got real lite. Felt like I had a leak. Pulled over, no leaks, and the master cylinder was full. An older gentlemen came over and asked what happened. I explained and he said air in the system.
But, not at that time. I pushed on the brake pedal and master cylinder moved to the right. The inside nut was loose. Wierd to most, but not to me. (long story short, I did not tighten it a while back when I was going to R&R the booster.) tightened it up and pedal was fine.
Well, today when the car got real fricking hot, 235, oil 250 in stop n go with ac on.. The brakes did the same thing. So, I pulled over, and pulled the master cylinder cap off, and it had a little bit of foam looking substance on the caps rubber. Fluid was black as hell. Air in system? I did brake bleeding years ago, but manually in garage.. Should I have them done a different way?
Master cylinder is new GM, braided lines. About 2 years old, less than 3000 miles, but all city. I have Hawk HPS pads, C5 front brakes.. Brakes fine, pedal has always, since 1996 (second owner on 93) been hard.
When I start car, pedal goes down, but pumps up quick. Vacuum to booster is about 14inches. Cam/396 lopey..
But, not at that time. I pushed on the brake pedal and master cylinder moved to the right. The inside nut was loose. Wierd to most, but not to me. (long story short, I did not tighten it a while back when I was going to R&R the booster.) tightened it up and pedal was fine.
Well, today when the car got real fricking hot, 235, oil 250 in stop n go with ac on.. The brakes did the same thing. So, I pulled over, and pulled the master cylinder cap off, and it had a little bit of foam looking substance on the caps rubber. Fluid was black as hell. Air in system? I did brake bleeding years ago, but manually in garage.. Should I have them done a different way?
Master cylinder is new GM, braided lines. About 2 years old, less than 3000 miles, but all city. I have Hawk HPS pads, C5 front brakes.. Brakes fine, pedal has always, since 1996 (second owner on 93) been hard.
When I start car, pedal goes down, but pumps up quick. Vacuum to booster is about 14inches. Cam/396 lopey..
Drifting
Joined: May 2008
Posts: 1,695
Likes: 491
From: Denver, NC
Moisture in the fluid will boil and cause a low pedal. Then when it cools it will seem normal again. If the fluid is black, you need to bleed the entire system. Then exercise the ABS and bleed some more.
Last edited by Ed Ramberger; Aug 23, 2019 at 07:32 PM.
Burning Brakes
Joined: May 2002
Posts: 755
Likes: 42
From: Sierra Foothills, State of Jefferson
Redline, Amsoil, Castrol, ATE, a bunch of others.
I use one of these to flush and bleed:
I use one of these to flush and bleed:
Race Director
Joined: Oct 2011
Posts: 16,096
Likes: 820
From: Dallas Texas
2025 C4 of the Year Finalist - Modified
Redline, Amsoil, Castrol, ATE, a bunch of others.
I use one of these to flush and bleed: Motive Power Bleeder
I use one of these to flush and bleed: Motive Power Bleeder
Drifting
Joined: May 2008
Posts: 1,695
Likes: 491
From: Denver, NC
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Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
Redline, Amsoil, Castrol, ATE, a bunch of others.
I use one of these to flush and bleed: Motive Power Bleeder
I use one of these to flush and bleed: Motive Power Bleeder
Thoughts
Thread Starter
Race Director
Joined: Jan 2012
Posts: 17,062
Likes: 166
From: United States
used the pressure bleeder. All fluid is clear now. DOT4.
Still need to adjust booster rod. I know that rod was moved years ago when I put it on..
Still need to adjust booster rod. I know that rod was moved years ago when I put it on..
Last edited by krackenvette; Aug 25, 2019 at 04:10 PM.