Good news and bad news with the master cylinder from hell
06-17-2007, 03:54 PM
#22
Safety Car
I've heard of cases where the brake system was bled and working well until there was an ABS event, where the ABS pump and valving forced the trapped air inside the ABS system out into the main braking system, and no more brakes.
Some vehicles have ABS systems that can be bled without special scan-tools. My 2002 Ford Ranger ABS system CANNOT be bled without the proper scan-tool to command the ABS valves to open while bleeding.
Tom Piper
06-17-2007, 05:16 PM
#23
Melting Slicks
Thread Starter
I do not remember if the 92 Vette has ABS, but I have a 94 and when you change the master cylinder the service manual indicates that firts you have to install the bench bleed master cylinder , then you have to bleed the ABS modulator that is located in the compartment behind the drivers seat.
Then you have to bleed the right rear caliper, next the left rear, after that the right front and finally the left front.
I did that and I am not having problems for now, but I have found that if I drive the car hard, braking hard the braking fluid will boil and what you describe as your problem happens to me. So bleeding a little will bring my brake to normal.
Then you have to bleed the right rear caliper, next the left rear, after that the right front and finally the left front.
I did that and I am not having problems for now, but I have found that if I drive the car hard, braking hard the braking fluid will boil and what you describe as your problem happens to me. So bleeding a little will bring my brake to normal.
My 92 does have abs. Do I have to bleed the abs modulator when doing a master cylinder swap?
06-17-2007, 05:17 PM
#24
Melting Slicks
Thread Starter
How much of the brake system have you changed?
I put a full wilwood 4 wheel disk system on my Camaro last winter, and replaced all the brake lines. Starting from empty, I moved nearly 3 GALLONS of brake fluid thru the system to get a good pedal. I used a mitivac on the bleeders rather than pushing the pedal. Ended up rigging it to one of those empty quart jars of DOT4 so I could recycle the stuff.
Just keep bleeding.
I put a full wilwood 4 wheel disk system on my Camaro last winter, and replaced all the brake lines. Starting from empty, I moved nearly 3 GALLONS of brake fluid thru the system to get a good pedal. I used a mitivac on the bleeders rather than pushing the pedal. Ended up rigging it to one of those empty quart jars of DOT4 so I could recycle the stuff.
Just keep bleeding.
06-17-2007, 05:30 PM
#25
Melting Slicks
Thread Starter
Qwiketz, When you are bleeding, are you having another pump the brake pedal for you?
I'm doing it on my own with me pushing down the brake pedal. I have the speed bleeders installed on all my calipers
Second, How are you opening the bleeder valve at the caliper? I just barely crack it as the pedal is depressed, the pressure builds and forces fluid/air bubbles through. Then I close it well before the brake pedal hits the floor.
Are you using any type of hose on top of the bleeder valve? You should use some clear fish tank hose that empties into a clear Coke bottle type receptacle. So, you place a Box end 10mm on the bleeder valve, then you push a piece of hose over the opening or nipple, then place the end of that hose down in a bottle. I'm currently using clear plastic tubing attached to the speed bleeder and then into a 1 gallon water container. It keeps things clean and helps me keep track of how much is actually coming out.
This does a few things for you.
A). It gives you a cushion on the timing of opening and closing the nipple. If you don't use the hose, and you allow the pedal to go all the way to the floor before closing the nipple, you stand a chance of drawing air back in via the nipple. With the hose in place there will be fluid there, greatly diminishing your chances of drawing in air.
B) With the hose there you can see the air bubbles as they emerge. You are looking for the air bubbles as this confirms that you have pushed enough fluid through that particular line. The Fluid should at this time change from nasty gray to clear.
C) the coke bottle catches the Fluid. Not that you want to use it again as the old stuff is contaminated but you don't want a mess either. Also, in my case I can never find clear hose that fits. I usually wind up using vacuum hose that is Black. The Bottle shows me the two things described in (B). First with the vacuum hose at the very bottom submerged in fluid, I can see the air bubbles when they emerge, and I can see the state of the fluid. Is it gray or is it clear?
And if you are pushing a lot of fluid for whatever reason, I guess if you pour out the gray stuff and just catch new clear stuff you could reuse it.
Remember, you are looking for the air bubbles. It is not a matter of whether or not air is in there, rather, Air is in there. Your job is to get it out. if you barely crack the bleeder nipple, you also "hear" the air as it forces through the tiny opening.
The Right Rear Caliper is a long way from the MC. I almost felt like I was doing something wrong do to the time it took to bleed that one. So how do you know when a line is bled? I can't tell any difference in pedal feel and the tubing is big enough diameter that it's hard to tell if any bubbles are coming out. I've just been pumping the thing about 100 times or so per corner.
Then.....then I thought I was also doing something wrong because there was no pedal until I bled the last caliper. I was so sure that this was wrong I repeated the entire process of bleeding just make sure. This also means that if you didn't push enough through on that RR caliper, you may not have any pedal even if you did the other three correctly.
Lastly, a brake bleed job shouldn't take....at the most....a large bottle of Dot 3. Three gallons of use means something was not going right.
I'm doing it on my own with me pushing down the brake pedal. I have the speed bleeders installed on all my calipers
Second, How are you opening the bleeder valve at the caliper? I just barely crack it as the pedal is depressed, the pressure builds and forces fluid/air bubbles through. Then I close it well before the brake pedal hits the floor.
Are you using any type of hose on top of the bleeder valve? You should use some clear fish tank hose that empties into a clear Coke bottle type receptacle. So, you place a Box end 10mm on the bleeder valve, then you push a piece of hose over the opening or nipple, then place the end of that hose down in a bottle. I'm currently using clear plastic tubing attached to the speed bleeder and then into a 1 gallon water container. It keeps things clean and helps me keep track of how much is actually coming out.
This does a few things for you.
A). It gives you a cushion on the timing of opening and closing the nipple. If you don't use the hose, and you allow the pedal to go all the way to the floor before closing the nipple, you stand a chance of drawing air back in via the nipple. With the hose in place there will be fluid there, greatly diminishing your chances of drawing in air.
B) With the hose there you can see the air bubbles as they emerge. You are looking for the air bubbles as this confirms that you have pushed enough fluid through that particular line. The Fluid should at this time change from nasty gray to clear.
C) the coke bottle catches the Fluid. Not that you want to use it again as the old stuff is contaminated but you don't want a mess either. Also, in my case I can never find clear hose that fits. I usually wind up using vacuum hose that is Black. The Bottle shows me the two things described in (B). First with the vacuum hose at the very bottom submerged in fluid, I can see the air bubbles when they emerge, and I can see the state of the fluid. Is it gray or is it clear?
And if you are pushing a lot of fluid for whatever reason, I guess if you pour out the gray stuff and just catch new clear stuff you could reuse it.
Remember, you are looking for the air bubbles. It is not a matter of whether or not air is in there, rather, Air is in there. Your job is to get it out. if you barely crack the bleeder nipple, you also "hear" the air as it forces through the tiny opening.
The Right Rear Caliper is a long way from the MC. I almost felt like I was doing something wrong do to the time it took to bleed that one. So how do you know when a line is bled? I can't tell any difference in pedal feel and the tubing is big enough diameter that it's hard to tell if any bubbles are coming out. I've just been pumping the thing about 100 times or so per corner.
Then.....then I thought I was also doing something wrong because there was no pedal until I bled the last caliper. I was so sure that this was wrong I repeated the entire process of bleeding just make sure. This also means that if you didn't push enough through on that RR caliper, you may not have any pedal even if you did the other three correctly.
Lastly, a brake bleed job shouldn't take....at the most....a large bottle of Dot 3. Three gallons of use means something was not going right.
06-17-2007, 05:42 PM
#26
Instructor
Member Since: Sep 2006
Location: Yorkville IL
Posts: 161
Likes: 0
Received 0 Likes
on
0 Posts
Just keep at it.
You are moving fluid, so the air will come out with it eventually.
You are done when you have a pedal.
One trick that was in the willwood manual that's worth a try... After bench bleeding the master and mounting it, and initially bleeding by cracking open the fluid lines at the master with pressure on (a step I skipped, my Camaro's underhood is highly detailed, and I went to every effort to save the paint from brake fluid... and paid the price wtih excessive bleeding time.)
They then suggested to just ticckle the brake pedal while watching the ports in the master for bubbles. I did get quite a bit of air out that way.
It still took more than forever, and today I bled them again, pedal was mushy. I got more bubbles out of 3 calipers, and the pedal is high and hard again. All my connections are bone dry, and the master level was still full. If I"m doing something wrong, I'd be all over listening to anyone with a constructive suggestion or two.
Lacking that, just keep bleeding.
You are moving fluid, so the air will come out with it eventually.
You are done when you have a pedal.
One trick that was in the willwood manual that's worth a try... After bench bleeding the master and mounting it, and initially bleeding by cracking open the fluid lines at the master with pressure on (a step I skipped, my Camaro's underhood is highly detailed, and I went to every effort to save the paint from brake fluid... and paid the price wtih excessive bleeding time.)
They then suggested to just ticckle the brake pedal while watching the ports in the master for bubbles. I did get quite a bit of air out that way.
It still took more than forever, and today I bled them again, pedal was mushy. I got more bubbles out of 3 calipers, and the pedal is high and hard again. All my connections are bone dry, and the master level was still full. If I"m doing something wrong, I'd be all over listening to anyone with a constructive suggestion or two.
Lacking that, just keep bleeding.
06-17-2007, 07:15 PM
#27
Le Mans Master
Sorry, I am just old school on some of that stuff.
Pump, hold, release.............pump, hold, release...
My wife used to hate brake bleed jobs, now my 14 year old hates them.
06-18-2007, 01:35 PM
#28
Melting Slicks
Do you want help? I am usually at the caliper. I've never used one of those kits. Do you have a neighborhood kid that will pump the brakes for you?
Sorry, I am just old school on some of that stuff.
Pump, hold, release.............pump, hold, release...
My wife used to hate brake bleed jobs, now my 14 year old hates them.
Sorry, I am just old school on some of that stuff.
Pump, hold, release.............pump, hold, release...
My wife used to hate brake bleed jobs, now my 14 year old hates them.
100%The old fashion "pump....release....pump....release" worked well for me.
Remember....
If your "speed bleeders" are loosened a bit too much, and you do not have di-electric greese on the bleeder threads, you do run the risk of sucking air back into the calipers through the threads....
BTW, I did not bleed my ABS unit, and I didn't have any issues. I will be honest and say that since I changed out my MC and bled the system, I also have not had an "ABS event".......I am almost inclined to induce an ABS event to see if I loose my brakes. I would do this somewhere safe of course, using emergency brake if needed to slow the car down slowly to a halt.....
Last edited by MikeC4; 06-18-2007 at 01:46 PM.
06-18-2007, 02:53 PM
#30
Former Vendor
I have put new systems in two different cars this past year, including my vette with all new lines when I put in the solid rear.
With both I opened the bleeders and let about 1 reservoir bleed through keeping it from going empty.
I then started with the wheel furthest away from the master and used a vacuum pump to pull about 1/4 of a reservoir through each while slightly tapping on the calipers. With an few brief motors there was only fluid flowing with no signs of air,,,,I would pump it to get about 10" on the vacuum pump and then quickly close the bleeders. did this for each of them and everything was fine.
Sound to be like you have air stuck in the mastercylinder or a bad mastercylinder. Some of the newer vehicle have a check valve that shuts off the fluid to the rear if you get low on fluid.....not sure if the year you have does or not. They all require a different way to unlock it if its activated. Are you get fluid from them all? You won't get any more fluid if the switch sticks.......my brother with a newer GM vehicle had this happen - a technician had to unlock it.
With both I opened the bleeders and let about 1 reservoir bleed through keeping it from going empty.
I then started with the wheel furthest away from the master and used a vacuum pump to pull about 1/4 of a reservoir through each while slightly tapping on the calipers. With an few brief motors there was only fluid flowing with no signs of air,,,,I would pump it to get about 10" on the vacuum pump and then quickly close the bleeders. did this for each of them and everything was fine.
Sound to be like you have air stuck in the mastercylinder or a bad mastercylinder. Some of the newer vehicle have a check valve that shuts off the fluid to the rear if you get low on fluid.....not sure if the year you have does or not. They all require a different way to unlock it if its activated. Are you get fluid from them all? You won't get any more fluid if the switch sticks.......my brother with a newer GM vehicle had this happen - a technician had to unlock it.
06-18-2007, 04:42 PM
#31
Melting Slicks
Thread Starter
yeah, I went through a couple resevoirs worth the fluid on each one. I'd top it off each time the fluid in the res dropped at all. I tried to take a look at the clear tubing for bubbles while my girlfriend pumped the pedal.
06-18-2007, 05:29 PM
#33
Melting Slicks
Thread Starter
yup, everything is clean and clear at this point. The old stuff was dark greenish brown. It looked nasty.
BTW, when bleeding the brakes, I was still seeing a few tiny, tiny bubbles, about the size of the tip of a pin. The bubbles appeared somewhat sporadically; there's not many of them at all. I thought that maybe these tiny, tiny bubbles were potentially caused by air getting sucked through the threads on the speed bleeders. Anyone see that before?
BTW, when bleeding the brakes, I was still seeing a few tiny, tiny bubbles, about the size of the tip of a pin. The bubbles appeared somewhat sporadically; there's not many of them at all. I thought that maybe these tiny, tiny bubbles were potentially caused by air getting sucked through the threads on the speed bleeders. Anyone see that before?
06-18-2007, 09:26 PM
#34
Le Mans Master
yup, everything is clean and clear at this point. The old stuff was dark greenish brown. It looked nasty.
BTW, when bleeding the brakes, I was still seeing a few tiny, tiny bubbles, about the size of the tip of a pin. The bubbles appeared somewhat sporadically; there's not many of them at all. I thought that maybe these tiny, tiny bubbles were potentially caused by air getting sucked through the threads on the speed bleeders. Anyone see that before?
BTW, when bleeding the brakes, I was still seeing a few tiny, tiny bubbles, about the size of the tip of a pin. The bubbles appeared somewhat sporadically; there's not many of them at all. I thought that maybe these tiny, tiny bubbles were potentially caused by air getting sucked through the threads on the speed bleeders. Anyone see that before?
06-18-2007, 09:52 PM
#35
Team Owner
Member Since: May 2002
Location: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Posts: 24,337
Likes: 0
Received 17 Likes
on
16 Posts
You need to put teflon tape or pipe dope on the threads during bleeding, or the bubbles will never stop and you'll never know if you're done bleeding.
The size of the bubbles won't tell you anything really.
The size of the bubbles won't tell you anything really.
06-18-2007, 11:17 PM
#36
Melting Slicks
Thread Starter
yeah, I did get my girlfriend to help me. I couldn't believe how much fluid we put through that thing and still was getting sporadic tiny bubbles out of the system. I easily went through about a two to three gallons of brake fluid (recycling it through the system). I'd say we spent at least an hour and a half bleeding the brakes with about and hour and fifteen minutes on the rears.
06-26-2007, 01:49 AM
#37
Melting Slicks
Thread Starter
it occurred to me that I haven't bled the inside of the front calipers since I instaled the master. My brakes have one bleeder on the outside and one on the inside from what I recall. Hopefully this will help. I'm running the 4 piston brembos.
08-18-2007, 12:46 PM
#39
Team Owner
Member Since: Oct 2004
Location: altered state
Posts: 81,242
Received 3,043 Likes
on
2,602 Posts
St. Jude Donor '05
08-18-2007, 01:00 PM
#40
Melting Slicks
Thread Starter
hey guys. thanks to all that helped. I did get it resolved. The brakes are back but the pedal feel isn't as great as I'd like.
I'm currently working on replacing the rack and pinion unit, so I guess you could say when it rains, it pours. After that, I should be good other than an alignment and a new chip for the car.
I'm currently working on replacing the rack and pinion unit, so I guess you could say when it rains, it pours. After that, I should be good other than an alignment and a new chip for the car.