Anyone experienced this? Brake help needed

[visionguru]

Today, I replaced the rear brake shoes. The whole precedure was smooth and quick. Since I replaced the brake fluid pretty recently, and the brake paddle travel seems to suggest that my bleeding wasn't done properly.
So, I tried to bleed the rear brake AGAIN. I may have let the brake fluid in the reservior run too low. Now this is the symptom: With engine off, the brake pedal pumps up fine, but when I start the engine, the brake pedal travels to the floor with little effort.
Has anyone experienced this? I was out of brake fluid (gonna get some tomorrow). Will a breeding procedure fix this? or did I damaged my brake system? (there are no leaks, line ruptures).
Thanks for your comments.

[Strugglebucket]

with the engine off the pedal you get is just from pressurizing air in the booster. if when you start the car the pedal goes to the floor then you definately have a major amount of air in the lines.

you probably let air into the master cylinder by letting the reservior run to low. unless you have one of those bleeding kits which uses air pressure to force fluid out of the lines, you will need to bleed the master cylinder. otherwise, it will take FOREVER to get all the air out of the lines doing it manually. i think you may be able to get a kit from an auto parts store but i would just go to the junkyard and cut 2 brake line fittings off a honda and then use those with some vacuum hose. this might help: http://www.misterfixit.com/brakbld1.htm

[halxi]

that or your master cylinder is just shot and needs to be replaced.

[Deadhead]

If his master cylinder was shot, then he would probably have no resistance at all on the pedal, with the car on or off.

[halxi]

racerx had this problem with his prelude, he bled the lines but it didnt work, turned out to be the master cylinder.

If you think about it, it makes sense, with my car off i can build pressure until my pedal wont move at all if im standing on it. As soon as it turns on, all the pressure goes away. And everythings back to normal

[visionguru]

I am going to autozone to get brake fluids, and try to fully bleed the brakes. Hopefully, this can resolve the problem.

Maybe I didn't expain it clearly. Prior to my brake bleeding, the brakes are operating correctly. The symptom was caused by bleeding (during which I let the reservior run too empty).

[thabeana]

looks like ya answered your own question pretty much, huh? I have to bleed my brakes tonight as well, since I had to take my booster off to uninstall/install my alternator...haha I'll see if I run into the same problems

[visionguru]

Just an update on the symptoms I reported earlier. After more than 1 hour bleeding and run through a whole bottle (32 oz), the brake seems to be back to half normal. Now, with the engine off, the padel can become firm after pumping 3 times; when I start the engine, the pedal will drop about 1", and braking seems to be fine. However, there is still a problem: the padel will not hold at a long red light (2~3 min). It will fade gradually and I have to pump up the brake. Prior to my 1st brake bleeding, the braking system operates flawlessly (with 10+ year old fluid!). I am pretty sure this happens after my 1st bleeding procedure (which may have introduced air into the system).

One thing I've noticed (during the last bleeding): the fluid came out SOLID (no air bubbles at all for at least the 1st 10 open/close sessions), and then suddenly, there are a lot of bubbles came out, and then became solid again. So, here is the lession I learned: If you open the bleeder and no air bubbles, there still can be A LOT of air trapped in the system.

I am sure there are still air in the system. Will try another time.

[lostforawhile]

ok you let air into the master cyl,that means you have to bench bleed the master cyl. you need a couple of those fittings cut off from old lines at the junkyard that you can attach rubber hoses too, I'm trying to remember the exact procedure to do this though. you need those pieces of line so you can screw them into the master cyl. ports. does anyone remember the bench bleed procedure? I know I had to do this when I put in my new master cyl. I believe you remove the master cyl. from the car,place it in a vise with rags in the jaws to protect it, then you screw in those fitting with rubber hoses on the ends. these hoses go into a glass jar with brake fluid in it. you then have to pump the master cyl. piston by hand,to force all the air out. I can't remember if a rod came with the master cyl. or not,there was something in the kit that allowed you to manually operate the cyl. I believe you have to do this because the power booster rod doesn't move far enough to expell al the air. I do remember the directions were very specific about doing this. If you have to remove the master cyl,you might as well get a new one,then it will have the exact procedure. I do know most of them don't include the resevoir,so don't turn in the core until you make sure you have one. normally you have to switch it. as old as that master cyl. is,I would probably replace it anyway. when mine went,it failed with no warning. I replaced every single part in my brake system,even the hard lines. I just wouldn't trust old brake parts.

[Strugglebucket]

you can just run the lines back into the reservior, no need to use a jar. preferably use clear hose so you can see the tiny bubbles better. use a flathead screwdriver to pump the piston slowly. make sure the bubbles exit the hose and float to the surface before you let the piston out on each stroke so you're not just sucking air back in.
when you go to install the cylinder back in the car some of the fluid will leak out but don't worry about air going back in because there are check valves that keep that from happening.

[lostforawhile]

oh,the reason I sugested using a jar was so if you flush out any dirt while you are doing this,it doesn't get back into the master cy.oh the book says to bleed the brakes diagnlly.left front,right rear,right front left rear. this is the way they are connected to the master cyl.

[SephirXV]

Similar problem:
I have not bled, opened, or in any other way touched my brake system. But I noticed one day that braking pedal was a little mushy, but more importantly that when braking, as to a stop, if I let out on the pedal at all, I would suddenly have almost no pressure. Releasing the pedal all the way would allow pressure to develop. So I have to remember when stopping to let out all the way, else I'll bouce off whoever is front of me despite putting the pedal to the floor.
I don't understand how all of the power assist stuff operates on my car, but I did check the check valve in the air hose that leads into the engine block, no problems.

[cardoc33]

If after an hour of bleeding, you should have all the air out. Hondas just aren't that hard to bleed.
If the pedal fades under pressure, that would mean the master is bad.

[lostforawhile]

Similar problem:
I have not bled, opened, or in any other way touched my brake system. But I noticed one day that braking pedal was a little mushy, but more importantly that when braking, as to a stop, if I let out on the pedal at all, I would suddenly have almost no pressure. Releasing the pedal all the way would allow pressure to develop. So I have to remember when stopping to let out all the way, else I'll bouce off whoever is front of me despite putting the pedal to the floor.
I don't understand how all of the power assist stuff operates on my car, but I did check the check valve in the air hose that leads into the engine block, no problems.

you have a bad master cyl. you need to get that fixed pronto. even if your booster fails you still have brakes,you just have to push the pedal harder. all the brake booster does is help push the pushrod that operates the master cyl. if you have a good master cyl. you can stomp on the brakes with total booster failure and still have brakes.

[visionguru]

Today, I drived my car for one hour. I found that it can hold at red lights/stops . No fade anymore. I haven't tried high speed stops yet.
I believe there are still a little bit air in the system. Maybe overnight, the air bubbles have moved to less critical places, or maybe air bubbles came out through the reservior by themselves (took a long while). Anyway, the brake fade symptom has gone (during 1 hour city driving).
Many friends here pointed to my master cylinder, and I think that makes a lot of senses. However, the brake never fade BEFORE I bleed the brake fluid. So, unless I damaged it during the bleeding procedure, the fade was cause by the bleeding.
One more thing: I accidentally pulled out the piston of wheel cylinder when replacing the rear brake shoes. I just wiped out some brown deposits with paper towel, and wash the cylinder and pistons with fresh brake fluid. I was surprised that after 16 years, i cannot tell if there is anything worn on the cylinders. I simply put the pistons back, and there is absolutely no leak. These Hondas are of good quality.
The outside of the rear brake drums have some rust, but when I measured the diameter using a caliper, it's 200mm (same as a new drum), and the friction surface is very smooth.

[lostforawhile]

Today, I drived my car for one hour. I found that it can hold at red lights/stops . No fade anymore. I haven't tried high speed stops yet.
I believe there are still a little bit air in the system. Maybe overnight, the air bubbles have moved to less critical places, or maybe air bubbles came out through the reservior by themselves (took a long while). Anyway, the brake fade symptom has gone (during 1 hour city driving).
Many friends here pointed to my master cylinder, and I think that makes a lot of senses. However, the brake never fade BEFORE I bleed the brake fluid. So, unless I damaged it during the bleeding procedure, the fade was cause by the bleeding.
One more thing: I accidentally pulled out the piston of wheel cylinder when replacing the rear brake shoes. I just wiped out some brown deposits with paper towel, and wash the cylinder and pistons with fresh brake fluid. I was surprised that after 16 years, i cannot tell if there is anything worn on the cylinders. I simply put the pistons back, and there is absolutely no leak. These Hondas are of good quality.
The outside of the rear brake drums have some rust, but when I measured the diameter using a caliper, it's 200mm (same as a new drum), and the friction surface is very smooth.

i'm glad they are working again,don't worry about the rust on the ouside of the brake drums,they are cast iron and this is normal. if you want to,you can mask off the inside of the drum,wire brush off the rust,and use one of those new brake paints.it sounds like someone has been servicing the brakes on your car,I doubt the rubber boots have lasted all these years by themselves, the ozone in the air makes them crack with time. probably someone has taken care of the car over the years. this is a good sign. someone cared and didn't let it get ragged out.

[lostforawhile]

I really would reccomend replacing all of the parts in any brake system that is over 15 years old,just for your safety,you never know when any old rubber part is going to fail. especially hoses,they make look fine but could suddenly rupture without warning. it doesn't make sense to do a lot of work on your car without making sure the brakes are solid first.

[Strugglebucket]

if there is only a tiny bit of air in the system you won't notice it...until you try and drive it on a really hot day.

[Oldblueaccord]

Today, I drived my car for one hour. I found that it can hold at red lights/stops . No fade anymore. I haven't tried high speed stops yet.
I believe there are still a little bit air in the system. Maybe overnight, the air bubbles have moved to less critical places, or maybe air bubbles came out through the reservior by themselves (took a long while). Anyway, the brake fade symptom has gone (during 1 hour city driving).
Many friends here pointed to my master cylinder, and I think that makes a lot of senses. However, the brake never fade BEFORE I bleed the brake fluid. So, unless I damaged it during the bleeding procedure, the fade was cause by the bleeding.
One more thing: I accidentally pulled out the piston of wheel cylinder when replacing the rear brake shoes. I just wiped out some brown deposits with paper towel, and wash the cylinder and pistons with fresh brake fluid. I was surprised that after 16 years, i cannot tell if there is anything worn on the cylinders. I simply put the pistons back, and there is absolutely no leak. These Hondas are of good quality.
The outside of the rear brake drums have some rust, but when I measured the diameter using a caliper, it's 200mm (same as a new drum), and the friction surface is very smooth.

You can mess up a MC especially the palstic ones by pushing to hard when bleeding if you used the 2 man method. The pedal should never "hit the floor" literally its done if you do.

The rear drums fall outta adjustment in 3-9 months so unless you really hammer the brakes the shoes never hit the drum even. Thats why you here on people going 150k miles on rear shoes. There not being used .

Brake pistons generaly stay good if the seals stay OK and the fluid is changed once in a while. It the moisture in the fluid that rust them up. Brake fluid wants to draw up moisture is one of its bad qualities and should be changed quite a bit. I use a turkey baster and suck up the old and add new about every 6 months when I adjust my rear brakes shoes. I like the pedal nice a firm.

wp

[lostforawhile]

if your rear brake shoes are going out of adjustment,you need to replace your adjuster assembly,the rachet and pawl wear out in time.every time you press the brake pedal the rear shoes readjust themselves. brakes that need adjusting haven't been made since the seventies. as far as saying that the brake seals don't wear out,thats a dangerous assumption,they have a finite number of cycles before fatigue causes them to start failing,just like my brand new looking brake hose that failed a few years ago. the reason the rear brakes don't wear as fast,has nothing to do with the shoes touching the drums,which they actually should slightly,they should have a slight amount of drag. it's because the proportioning valve limits rear brake bias to only about 25 percent,the front brakes do most of the work,on a rear disc car the proportioning valve is different,so the bias is different. the turkey baster method wil do nothing to protect your brakes from moisture,the only way to do this is to bleed out the system every few years until all the old fluid has been exchanged. most of the fluid is in the brake master cyl,the lines,and the calipers,the resovoir is only a small percentage of the fluid. it's reason for existince is so that as the brake pads wear and the shoes wear, there is extra fluid to compensate for longer piston travel in the brakes.

[SephirXV]

you have a bad master cyl. you need to get that fixed pronto. even if your booster fails you still have brakes,you just have to push the pedal harder. all the brake booster does is help push the pushrod that operates the master cyl. if you have a good master cyl. you can stomp on the brakes with total booster failure and still have brakes.

If the problem were in the MC, would it not have the same issue during engine off?

[visionguru]

OK, I'm gonna replace the master cylinder. I just remembered one incident that happened on July 4th, when I drove down town to see the fire works. The traffic was horrible (slower than walking), and the weather was hot! At one stop sign on my way back, the brake padel sink to the floor and the car was stil moving (I had to pull the ebrake). This was before my recent brake fluid bleeding.
I went to Autozone & AdvancedAuto looking for MC. However, they only have re-manufactured ones. After reading the posts here, I realized the importance of a good MC, which is virtually the heart of the brake system. Don't really like the looks of the remanufactured ones from Autozone. To my surprise, the remanufactured one comes with bench bleeding fittings (which means I don't have to visit a J-yard to cut off fittings for bench bleeding).
I am considering Honda OEM master cylinders, which I am not sure whether it will come with those fittings. Can anyone tell me if brand new MCs come with bleeding fittings? Any problem with re-manufactured ones?
Thanks, guys.

[lostforawhile]

OK, I'm gonna replace the master cylinder. I just remembered one incident that happened on July 4th, when I drove down town to see the fire works. The traffic was horrible (slower than walking), and the weather was hot! At one stop sign on my way back, the brake padel sink to the floor and the car was stil moving (I had to pull the ebrake). This was before my recent brake fluid bleeding.
I went to Autozone & AdvancedAuto looking for MC. However, they only have re-manufactured ones. After reading the posts here, I realized the importance of a good MC, which is virtually the heart of the brake system. Don't really like the looks of the remanufactured ones from Autozone. To my surprise, the remanufactured one comes with bench bleeding fittings (which means I don't have to visit a J-yard to cut off fittings for bench bleeding).
I am considering Honda OEM master cylinders, which I am not sure whether it will come with those fittings. Can anyone tell me if brand new MCs come with bleeding fittings? Any problem with re-manufactured ones?
Thanks, guys.

I bought a remanufactured one from nappa,havn't had any problems,they have a really good rep for brake parts,I wouldn't trust autozone or advance for much of anything,let alone brake parts.

[cardoc33]

The OE masters I buy do not come with extra fittings. But you don't need them. Put a phillips screwdriver in the back of the master, this will act as a pushrod(it wont damage it).Fill the resivoir with fluid and cap it, then cover the 2 threaded holes with your fingers. Using your chest, push the screwdriver all the way into the master while releasing your fingers. Then cover the holes again as you release pressure on the screwdriver. Repeat. This will alternately push air out and draw fluid in. Two or three strokes and it's bled. It sound funny and it's a bit messy, but it's quick and it's bled enough to install it where you can bleed it again at the master and at the wheels.
Not sure what Honda will charge you for a master, but I could sell you an OE unit for $71.00 shipped to Chicago.

[visionguru]

The OE masters I buy do not come with extra fittings. But you don't need them. Put a phillips screwdriver in the back of the master, this will act as a pushrod(it wont damage it).Fill the resivoir with fluid and cap it, then cover the 2 threaded holes with your fingers. Using your chest, push the screwdriver all the way into the master while releasing your fingers. Then cover the holes again as you release pressure on the screwdriver. Repeat. This will alternately push air out and draw fluid in. Two or three strokes and it's bled. It sound funny and it's a bit messy, but it's quick and it's bled enough to install it where you can bleed it again at the master and at the wheels.
Not sure what Honda will charge you for a master, but I could sell you an OE unit for $71.00 shipped to Chicago.

Thanks for the very helpful tip on bench bleeding. I've already got the master cylinder before reading your post. I haven't installed it yet.


Today (it's cold outside), I drove my car for 2 hours within the intention of testing it at every stop/traffic light. The brake seemed to be working flawlessly. However, last week, the brake was fading after 30min city driving.


It seems to me that my brake fading problem is temperature related. There has never been a problem at the 1st 30min. sometimes it fades (only a couple of times), while most of the time, it works just fine.


My question is: does a symptom like this point to ONLY the master cylinder or it could be something else?


Thanks for any further tips.