How bleeding an old master cylinder can increase failure rate
10-09-2010, 01:06 PM
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How bleeding an old master cylinder can increase failure rate
Have you ever wondered why some brake master cylinders seem to fail after a big upgrade (like caliper replacement), after you have owned your car for many years with no problems. Or why you seem to lose your brakes shortly after you have bled them?
There were previous articles on this issue on Honda-tech and another forum I frequently visit, however I can't seem to find them anymore. So I will just reiterate what was discussed in those articles with a picture I made.
Now despite all of this, it would be a safe bet that a master cylinder that has had REGULAR fluid changes annually would last much longer than one that has never had a fluid change. The reason for this is because, a MC that has had regular bleeding's on an annual basis would not have all that crap built up. When you bleed it, the seal is forced to push out the debris, keeping the cylinder bore clean even past it's normal travel.
Symptoms:
Symptoms of a master cylinder on its way out include:
-Spongy pedal, or very soft pedal
-Pedal travelling all the way to the floor
-No loss of fluid in the reservoir, but horrible braking performance
-Initial pedal bite, but then the pedal is able to sink to the floor and the brakes loose it's effectiveness.
Solution:
-Replace your master cylinder with a new one. Ensure that it is bench bled before installing it into the car.
-Do NOT reuse a used master cylinder (unless you are sure that it has been maintained regularly), I personally would not risk my life on reusing used master cylinders.
pay the extra money to get a new one, or at the very least an oem remanufactured master cylinder.
-If your MC is new, this is another reason why you should regularly be changing out your brake system. Not only will it keep your fluid in top shape and remove any traces of water, but it will allow your MC to last longer.
Evidence that this actually does occur
My personal story, I bought my 92 Integra back in 2000, after buying it I did the full maintenance and tune-up. Brake pads, timing belt, water pump, full fluid flushes, etc. After a few days my brakes seemed really mushy. Thinking that I introduced air bubbles into my brake system, I re-bled them. The next day, my brakes were completely gone! <Insert scary moment here> So I had my car towed back, and changed the M/C. After looking at my old M/C, I could see that the previous owner most likely did not change out the fluid much, there was a thin layer of build-up with a powery chalky texture covering the walls of the reservoir.
I have seen and heard of similar cases where this has occured as well, both in real life, and on the internet. So when you buy a really old car, one of the first things you should change is your M/C.
Above all, drive safe guys!
There were previous articles on this issue on Honda-tech and another forum I frequently visit, however I can't seem to find them anymore. So I will just reiterate what was discussed in those articles with a picture I made.
Now despite all of this, it would be a safe bet that a master cylinder that has had REGULAR fluid changes annually would last much longer than one that has never had a fluid change. The reason for this is because, a MC that has had regular bleeding's on an annual basis would not have all that crap built up. When you bleed it, the seal is forced to push out the debris, keeping the cylinder bore clean even past it's normal travel.
Symptoms:
Symptoms of a master cylinder on its way out include:
-Spongy pedal, or very soft pedal
-Pedal travelling all the way to the floor
-No loss of fluid in the reservoir, but horrible braking performance
-Initial pedal bite, but then the pedal is able to sink to the floor and the brakes loose it's effectiveness.
Solution:
-Replace your master cylinder with a new one. Ensure that it is bench bled before installing it into the car.
-Do NOT reuse a used master cylinder (unless you are sure that it has been maintained regularly), I personally would not risk my life on reusing used master cylinders.
pay the extra money to get a new one, or at the very least an oem remanufactured master cylinder.
-If your MC is new, this is another reason why you should regularly be changing out your brake system. Not only will it keep your fluid in top shape and remove any traces of water, but it will allow your MC to last longer.
Evidence that this actually does occur
My personal story, I bought my 92 Integra back in 2000, after buying it I did the full maintenance and tune-up. Brake pads, timing belt, water pump, full fluid flushes, etc. After a few days my brakes seemed really mushy. Thinking that I introduced air bubbles into my brake system, I re-bled them. The next day, my brakes were completely gone! <Insert scary moment here> So I had my car towed back, and changed the M/C. After looking at my old M/C, I could see that the previous owner most likely did not change out the fluid much, there was a thin layer of build-up with a powery chalky texture covering the walls of the reservoir.
I have seen and heard of similar cases where this has occured as well, both in real life, and on the internet. So when you buy a really old car, one of the first things you should change is your M/C.
Above all, drive safe guys!
Last edited by speedoptions.ca; 10-13-2010 at 10:05 AM.
10-12-2010, 04:49 PM
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Re: How bleeding an old master cylinder can increase failure rate
Good read, thank you. - Now Im super paranoid and replacing my 15/16 used MC for a new one.
10-12-2010, 05:14 PM
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Re: How bleeding an old master cylinder can increase failure rate
Don't let this scare you into not changing your brake fluid. Old fluid that has absorbed water will boil at moderate to high brake temperatures. Also, this moisture can cause corrosion, depending on what your brake lines are made of.
Honda recommends changing brake fluid every three years.
Be careful while pumping your brakes, only use short strokes, and you may avoid this problem.
Honda recommends changing brake fluid every three years.
Be careful while pumping your brakes, only use short strokes, and you may avoid this problem.
10-13-2010, 09:53 AM
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Re: How bleeding an old master cylinder can increase failure rate
Don't let this scare you into not changing your brake fluid. Old fluid that has absorbed water will boil at moderate to high brake temperatures. Also, this moisture can cause corrosion, depending on what your brake lines are made of.
Honda recommends changing brake fluid every three years.
Be careful while pumping your brakes, only use short strokes, and you may avoid this problem.
Honda recommends changing brake fluid every three years.
Be careful while pumping your brakes, only use short strokes, and you may avoid this problem.
10-13-2010, 03:21 PM
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Re: How bleeding an old master cylinder can increase failure rate
You don't actually need to pump your brakes to change the fluid, you can use the gravity method or a hand held vacuum pump and draw the fluid to you.
As long as you do not let air get in the lines by keeping the master full while your changing the fluid you won't have any problems.
I mostly work alone it seems that there is never anyone around to help me bleed brakes, and these ways always work for me.
If money is no problem a pressure bleeder is a good way also, I made a pressure bleeder out of a 1 gal bug sprayer and used an old master cyl cap with a piece of steel line attached to the cap for the feed line, it leaks a bit but it gets the job done.
As long as you do not let air get in the lines by keeping the master full while your changing the fluid you won't have any problems.
I mostly work alone it seems that there is never anyone around to help me bleed brakes, and these ways always work for me.
If money is no problem a pressure bleeder is a good way also, I made a pressure bleeder out of a 1 gal bug sprayer and used an old master cyl cap with a piece of steel line attached to the cap for the feed line, it leaks a bit but it gets the job done.
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