air in brakes, arrgh!!
02-23-2014, 12:30 PM
#1
Pro
Thread Starter
air in brakes, arrgh!!
So, brake pedal goes soft. I bleed front left, and everything is fine for a couple days. Then pedal goes soft again. Bleed front left, then front right just for the fun of it. Holy smokes, a bunch of air emulsion in right front line also.
No fluid leaks anywhere though. But obviously the system is letting air in somewhere. Never ran into this before, am inclined to change master cyl, but before I do, thought I'd ask if anyone heard of this. Thank you!
No fluid leaks anywhere though. But obviously the system is letting air in somewhere. Never ran into this before, am inclined to change master cyl, but before I do, thought I'd ask if anyone heard of this. Thank you!
02-23-2014, 04:37 PM
#4
Safety Car
"Brake fluid resides in a sealed, air-tight reservoir on top of the master cylinder. As the brake fluid level drops, air moves in to fill the void. Wait a minute -- didn't we just say that the system was air-tight? Well, unfortunately, air does get into the reservoir over time and it eventually makes its way into the rest of the braking system -- including your brake lines. Every time you open the cap to check your brake fluid level, you're letting air into the system. When the fluid is at the correct level, air isn't much of a factor; however, the more worn your brake pads are, the larger the void grows. That's one reason why it is so important to keep the fluid at the proper level."
02-23-2014, 06:54 PM
#7
Race Director
Member Since: Dec 2002
Location: SCMR Rat Pack'r Charter Member..Great Bend KS
Posts: 13,243
Received 176 Likes
on
129 Posts
While you are admitting air into the master cylinder reservoir when you remove the cap, you are not letting air into the brake lines.
Solution for the OP: bleed all lines periodically.
02-23-2014, 07:26 PM
#8
Le Mans Master
02-23-2014, 07:35 PM
#10
Safety Car
that the statement is misleading, rocco16......maybe the info in the following link may help:
http://www.s10forum.com/forum/f137/c...eeding-491204/
02-23-2014, 08:43 PM
#11
Melting Slicks
air cannot be intered into the system thru the master cyl unless it is so low that the port is exposted. If you have air in a system thst was previously bleed of air and all the sudden you have air. You have air intering the system below the level of the revisor. You sould never have to peiroty have to bleed air out of a brake system.
02-23-2014, 09:18 PM
#13
Race Director
On 1965-1982 Corvettes...due to the caliper is solidly mounted to the front spindle and the rear training arm...the run-out of the brake rotors and wheel bearing are critical. If these measurements are off enough...the pistons will move more than designed and either leak fluid or as I have experienced..suck air into the system without brake fluid leaking.
NOW...your cars brake system is different than that of a the years listed above. The calipers are not solidly mounted...but rather they float or move on pins. I have seen these pins run dry of lube and the rubber seals also go bad allowing water into the the cavity of the pins and cause the caliper not to move as designed...which can cause this problem of air getting into the system.
ARE YOU SURE that you do not have fluid leaking out of the back of the master cylinder when you removed and checked it???
Check your wheel bearing play also. They are not serviceable wheel bearings..so-to-speak...but rather a hub/bearing assembly where it is replaced all in one part.
"seabright"
You really need to think about deleting post #4. That information is not correct at all. There is no way for air to enter the brake system FROM the master cylinder reservoir as long as there is fluid covering the holes that feed the front and rear brakes. When fluid is being lost from some area of the brake system....the accordion seal in the cap of the master cylinder falls down and keeps the "air space" the same as if the fluid was at correct level and the seal back up in the cap. This is why you still have brakes. AND your brakes finally fail when the front and/or rear reservoir runs "dry" and then AIR gets into the system and you have little to no pedal. DISCLAIMER...OBVIOUSLY...if the leak is bad enough (not saying a small leak is GOOD)...you can loose brake REALLY FAST....or if your cap is bad and the rubber seal does not seal well...then this can cause for major issues also due to the seal will not drop down when fluid is being lost.
DUB
NOW...your cars brake system is different than that of a the years listed above. The calipers are not solidly mounted...but rather they float or move on pins. I have seen these pins run dry of lube and the rubber seals also go bad allowing water into the the cavity of the pins and cause the caliper not to move as designed...which can cause this problem of air getting into the system.
ARE YOU SURE that you do not have fluid leaking out of the back of the master cylinder when you removed and checked it???
Check your wheel bearing play also. They are not serviceable wheel bearings..so-to-speak...but rather a hub/bearing assembly where it is replaced all in one part.
"seabright"
You really need to think about deleting post #4. That information is not correct at all. There is no way for air to enter the brake system FROM the master cylinder reservoir as long as there is fluid covering the holes that feed the front and rear brakes. When fluid is being lost from some area of the brake system....the accordion seal in the cap of the master cylinder falls down and keeps the "air space" the same as if the fluid was at correct level and the seal back up in the cap. This is why you still have brakes. AND your brakes finally fail when the front and/or rear reservoir runs "dry" and then AIR gets into the system and you have little to no pedal. DISCLAIMER...OBVIOUSLY...if the leak is bad enough (not saying a small leak is GOOD)...you can loose brake REALLY FAST....or if your cap is bad and the rubber seal does not seal well...then this can cause for major issues also due to the seal will not drop down when fluid is being lost.
DUB
02-23-2014, 09:32 PM
#14
Advanced
Member Since: Jan 2014
Location: Mt. Airy Md
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
02-23-2014, 09:38 PM
#15
Pro
Thread Starter
Thanks DUB. I've worked lots of brake systems since '79 and never had one like this where there was air in the lines after repeated bleeding, with no sign of fluid leakage anywhere, your info helps me think a little. At first I thought, maybe water in the fluid, reacting with the iron and forming hydrogen or whatever but the rate of replenishment of the air was quicker than the kinetics of such gas formation could be, on a time scale. I appreciate you providing new avenues of thought.
02-23-2014, 09:39 PM
#16
Melting Slicks
02-23-2014, 10:09 PM
#17
Advanced
Member Since: Jan 2014
Location: Mt. Airy Md
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
So, brake pedal goes soft. I bleed front left, and everything is fine for a couple days. Then pedal goes soft again. Bleed front left, then front right just for the fun of it. Holy smokes, a bunch of air emulsion in right front line also.
No fluid leaks anywhere though. But obviously the system is letting air in somewhere. Never ran into this before, am inclined to change master cyl, but before I do, thought I'd ask if anyone heard of this. Thank you!
No fluid leaks anywhere though. But obviously the system is letting air in somewhere. Never ran into this before, am inclined to change master cyl, but before I do, thought I'd ask if anyone heard of this. Thank you!
02-23-2014, 10:23 PM
#18
Advanced
Member Since: Jan 2014
Location: Mt. Airy Md
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
Thanks DUB. I've worked lots of brake systems since '79 and never had one like this where there was air in the lines after repeated bleeding, with no sign of fluid leakage anywhere, your info helps me think a little. At first I thought, maybe water in the fluid, reacting with the iron and forming hydrogen or whatever but the rate of replenishment of the air was quicker than the kinetics of such gas formation could be, on a time scale. I appreciate you providing new avenues of thought.
02-23-2014, 10:46 PM
#19
Advanced
Member Since: Jan 2014
Location: Mt. Airy Md
Posts: 62
Likes: 0
Received 0 Likes
on
0 Posts
Thanks DUB. I've worked lots of brake systems since '79 and never had one like this where there was air in the lines after repeated bleeding, with no sign of fluid leakage anywhere, your info helps me think a little. At first I thought, maybe water in the fluid, reacting with the iron and forming hydrogen or whatever but the rate of replenishment of the air was quicker than the kinetics of such gas formation could be, on a time scale. I appreciate you providing new avenues of thought.
02-23-2014, 10:47 PM
#20
Pro
Thread Starter
First you always bleed the brake farthest from master cyl first then you bleed the other side. Next what shape are your pads in and i mean both sides. Just because 1 side looks good means nothing a hung up caliper can wear 1 pad and not the other. Just because you do not see brake fluid does not mean theres not leaking brakes. Brakes get so hot they 'll cook that b fluid off.
I was just lazy and did the front left "just to see", but it'd given me back a good hard pedal real quick so I just went along my ride that day, wanted to get out. I think I'll replace master cyl first , bleed it, then go from there. Thanks a bunch y'all