Braking problems

[FaizanSheikh]

Alright spiffyguido i got a question that will challenge your prelude godliness. The brakes on my 1991 prelude ALB si is giving me trouble. Ill start off with how it started. I went on vacation for 2 weeks and the car leaked brake fluid for some reason and it emptied out the brake fluid and stained my dashboard with the brake light. So, just like any other teen i procrastinated to fill the brake fluid and took me 3-4 days to get off my ass and fill the brake fluid. So now the car brake is all or nothing. Either i press down all the way to stop the car or not press the brakes at all because even if i press half way or 75% down the brakes dont work and dont stop or atleast stop the car. I figured that the car had some air in the brake lines so i bled the front two brakes and the rear passenger side brake. It didnt make any difference at all. The thing is before i start the car i can pump the brakes and it feels just any other car when u pump it such as resistance but when i start the car the brake pedal goes all the way down and does the stop or nothing. I can drive around town in it but i would rather fix it. So spiffyguido do you think its the master cylinder or something else? Thanks for all the replies guys. Appreciate it.

[RedRacer]

Absolutely sounds like a leak in the master cylinder. Needs to be replaced. Not an expensive repair for a good mechanic that you trust or if you want to do it yourself and have the tools, knowledge and patience to do it right. Remember, brakes are about the most important safety feature of the car. If you don't feel comfortable in doing the job yourself, it's worth it to pay a little extra and have someone else do it.

The biggest suggestion I have for you is to stop driving until you get it fixed because it's going to eventually fail suddenly and completely and you're going to be in a dangerous, possibly deadly scenario.

You can not rely on the E brake to keep you from running up the butt end of another car or under a large truck and decapitating yourself. And in most all cases of rear end collisions, the driver who hits the other car is automatically at fault. Dead or alive.

You mentioned that you bled the system at only three wheels. NOT GOOD.

Do ALL four and do them in this order:

Right Rear, Left Front, Left Rear, Right Front

Go check my write-ups on brake bleed/flush and brake fluid. It's good info to know.

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[FaizanSheikh]

Red, do you think it could be the brake booster? I see some oil leak out from it.

[spiffyguido]

Are you sure that the leak is coming from the booster, and not the master cylinder?

+1 for everything RedRacer said. I'd get the master cylinder fixed up pronto. You don't drive a car that has brake problems, because invariably, the problem will prevent you from stopping when you really need to. Master cylinders are not hard to replace, so start there.

Also, even if it is the brake booster, it shouldn't degrade your brake performance. The brakes work whether the booster is running or not.

[RedRacer]

I would say no, Faizan. It's most likely not the booster that is bad or the cause of your problem. The fluid you're seeing around it is residual fluid from the valve spring cylinder in the master cylinder, which is leaking, and that leaking fluid is running down the rod which goes through the booster, through the firewall and is attached to your brake pedal. Are you getting fluid in the floorboard of the car? Is it dripping off the bottom of your break pedal?

The booster does not retain fluid. When you apply your foot on the brake pedal it pushes a rod connected to the brake booster (the brake booster is the part that makes your car have power brakes, it operates with the vacuum from your engine), it is here in the brake booster that the force is multiplied. (without a brake booster it would take a lot of effort and strength to push on the brakes) This force is transmitted to the brake master cylinder, and it's inside the master cylinder that the mechanical movement is converted into hydraulic pressure.

The booster, which as you know is mounted on the firewall directly behind the master cylinder and, along with the master cylinder, is directly connected with the brake pedal. What it does in simple terms is amplifies the available foot pressure applied to the brake pedal so that the amount of foot pressure required to stop even the largest vehicle is minimal. Power for the booster comes from engine vacuum. The vacuum enters the booster through a check valve on the booster. The check valve is connected to the engine with a rubber hose and acts as a one-way valve that allows vacuum to enter the booster but does not let it escape. The booster itself is just an empty shell divided into two chambers by a rubber diaphragm. There's a valve in the diaphragm that remains open while your foot is off the brake pedal so that vacuum is allowed to fill both chambers. When you step on the brake pedal, the valve in the diaphragm closes. This separates the two chambers and the second valve opens to allow air into the chamber on the brake pedal side. This is what provides the power assist and is why when you lose engine power or shut the car off, the pedal becomes hard and the car is harder to stop. Power boosters are very reliable and rarely cause problems on their own.

The master cylinder is where the brake fluid is contained inside the cylinder and in the reservoir on top. (as you know) When you apply force against the brake master cylinder via your brake pedal, the valves inside the master cylinder create pressure , and this pressure is channeled through the brake lines. The first thing that the pressure encounters is the brake proportioning valve. The proportioning valve is in charge of distributing the right amount of pressure to each wheel. Without this valve, braking would be uneven and one or two wheels would lock up when you brake. This pressure then exits the brake proportioning valve and reaches the brake calipers located at the four wheels. (if the car is 4 wheel disc. if it is not four wheel disc, then it would apply to the two calipers on the front and the wheel cylinders on the rear) The caliper presses against the pads, the pads are pressed onto the rotors and this pressure squeezing on the rotors, which are attached to the wheel assembly, are what slows the wheel from rotating and brings the car to a stop.

I just like to explain things, so this way you know exactly how all this works and it will help you in understanding where to look for problems or what to look for.

To answer your question, no, I don't think this is your booster. It's your master and needs to be replaced. And considering the age of the car, it's most likely the original and it's about time for it to be replaced for sure.

Where are you located, by the way?

[FaizanSheikh]

Wow, i really like this community especially when its a almost-impossible question to answer. Thanks Red and spiffy. And also another question. I have 1989 Honda Accord LX parts car which uses carborator instead of fuel injectoar. Will a master cylinder work from the accord on a 1991 prelude SI ALB? And again thanks.
Iam in Long Island, NY btw

[spiffyguido]

It's very possible that the master cylinder from the Accord is the same. It's hard to say for sure though. If the input shaft is the same length, the mount bolts are in the same position and the size (diameter) of the cylinder is the same, go ahead and use it. My guess is that it's the same unit.

[RedRacer]

The Accord cylinder should work, but consider what you're doing. The Accord cylinder is older than the one in the Prelude which puts it at failure point realistically not too long after you install it in the Prelude, PROBABLY. That's not a sure thing but it very well could be the case. Especially if the cylinder has been sitting up on the Accord not being used with brake fluid in it for how long? Brake fluid attracts water. Water erodes and degrades metal parts and seals.

If you're trying to save money, in the long run by installing this older and not recently used master from the Accord, you're increasing your chances for another failure sooner than you want, and then you have to go through this all over again and it's going to cost you even more in your time and in money.

If you don't have the cash or don't want to spend the money on a brand new Honda unit, then go to AutoZone or O'Reilly or a place like that and just get a cheaper rebuilt unit.....again, you're running the same risk, but maybe not. Most remans come with a limited lifetime warranty.

I'd trust a remanufactured part before I would an old one that's been sitting up. Just my opinion.

Just FYI: If you have a good and honest mechanic (if you didn't want to do this yourself) he can get you a new Honda cylinder, installed and all for about 300 and some change.

[Crash_Control]

He has ALB I was wondering if in that age of ABS doe he require that goofy tool to bleed the ABS controller?

[RedRacer]

He has ALB I was wondering if in that age of ABS doe he require that goofy tool to bleed the ABS controller?

Would need yes, but there is no reason to bleed the ABS. Totally isolated and independent systems. That's a blessing. Unless there is a breach in that system, leave it alone. (unless you have knowledge of working on ABS systems, of course)

[Crash_Control]

Would need yes, but there is no reason to bleed the ABS. Totally isolated and independent systems. That's a blessing. Unless there is a breach in that system, leave it alone. (unless you have knowledge of working on ABS systems, of course)

Not having worked on That particular model of prelude so you are saying the abs controller operates a separate set of pistons in the calipers?

[RedRacer]

Would need yes, but there is no reason to bleed the ABS. Totally isolated and independent systems. That's a blessing. Unless there is a breach in that system, leave it alone. (unless you have knowledge of working on ABS systems, of course)

Not having worked on That particular model of prelude so you are saying the abs controller operates a separate set of pistons in the calipers?

Sorry, that's not what I meant to imply. I am not aware of any cars that have more than one piston, but some cars actually have anti-lock bleed valves on each wheel, as well as standard brake bleed valves. But Honda does not do that.

Working the ABS is a bit more complicated than most people are prepared for. Some will tell you that isn't true and you can just do it yourself the same way you would bleed any hydraulic system or closed fluid system. While the physical method is the same, there is more to it that is not. Keep reading.

What I'm saying is this: When you bleed the ABS system, it's a completely different animal. When you bleed the regular hydraulics on the braking system, it's done at the bleed valve at each wheel. When you bleed the ABS system, you are bleeding the accumulator and or the HCU (hydraulic control unit) itself and you're going to need scan tools, bleeder tools, etc. It can get a little complicated.

If you need to bleed the ABS, the HCU is what you work. Really the only reason you would need to do this is if air has gotten into the accumulator. The HCU is equipped with a bleeder screw that allows removal of trapped air. You attach a bleeder hose to the HCU bleeder valve to control the fluid discharge. Start the engine and then slowly open bleeder 1/8 to 1/4 turn to allow fluid and air to escape......but...

....It is a little bit more complicated than that because the accumulator is where the brake fluid is stored under extreme high pressure. The basic design is a steel "bulb" with a threaded outlet. Inside the bulb is a thick, rubber diaphragm that divides the bulb into two areas. The top area is filled with pressurized nitrogen gas. The bottom area is where the fluid is stored. That fluid is used for power assist and pressure modulation when the ABS system goes into action. The pump/motor fills the accumulator and in most cases is controlled by a pressure switch. The pressure switch has a high and low cutoff point to keep the volume of fluid in the accumulator within a specific range.

Because of all of this, the high pressure accumulator has to be discharged before you service it, work on it, bleed it, etc.

If you just jump into the accumulator and turn bleed valves open too much, brake fluid will discharge under high pressure, and depressurizing the accumulator like that can cause the diaphragm to fail. Then you're replacing the accumulator/HCU and you're talking serious cash.

Keeping all this in mind, this is why I say, leave the ABS system alone unless there is a known problem or you know there is air in the system, and even then, I highly recommend that you take it to a shop that works on ABS systems, or as a last resort, the Honda dealer.

[frank444]

call me an old chicken
Driving a car with brake problems is suicide.....
1 with the engine off
2 pump up the brake
3 keep pressure on the brake pedal
4 start the engine

if the pedal goes right to the floor its the master cylinder
if the pedal stays pumped up its something else......

parts from some cars are interchangeable
why fudgecrack around
i googled and found rebuilt master cylinder for like $25 http://www.rockauto.com/catalog/raframe ... 748k259644

New for $65
25 bucks sounds too cheap but if that price is right
..
if you dont have 40 dollars for fixing the brakes .....you have more important things to fix besides the brakes!