Rebuild brake master cylinder or purchase a replacement?
#1
Rebuild brake master cylinder or purchase a replacement?
For a '96 Civic CX, D16Y7 engine.
After bleeding the brakes due to how dirty the fluid was (it was pitch black), I started to encounter a sinking pedal when I am stopped at a light or stop sign. I mean, gradually but completely sinks to the floor at times. At first I thought there may have been air in the system still, so I went ahead and bled it again, but the same symptoms have occurred. After doing some quick research, it has been determined that it is a faulty brake master cylinder as it's most likely leaking internally.
That being said, what would be better yet more economical route to take: rebuild the brake master cylinder or replace the entire unit with a brand new one? If I can rebuild it with new seals or what not, I'd like to go that route, but I would rather seek the advice from others on here who have experience with both and can give their take on what's the best route to use.
Thanks!
After bleeding the brakes due to how dirty the fluid was (it was pitch black), I started to encounter a sinking pedal when I am stopped at a light or stop sign. I mean, gradually but completely sinks to the floor at times. At first I thought there may have been air in the system still, so I went ahead and bled it again, but the same symptoms have occurred. After doing some quick research, it has been determined that it is a faulty brake master cylinder as it's most likely leaking internally.
That being said, what would be better yet more economical route to take: rebuild the brake master cylinder or replace the entire unit with a brand new one? If I can rebuild it with new seals or what not, I'd like to go that route, but I would rather seek the advice from others on here who have experience with both and can give their take on what's the best route to use.
Thanks!
#2
Re: Rebuild brake master cylinder or purchase a replacement?
The MC may be fine, and the sinking pedal is caused by air still present in the hydraulic system.
Detail how you bled the system.
Detail how you bled the system.
#4
Re: Rebuild brake master cylinder or purchase a replacement?
^Good method.
You say gravity method but the procedure also involves pressing the brake pedal. Please clarify.
Did you bleed the wheels in the proper order?
Did you route the bleed hose UPWARD over spring and back down into waste container?
How many pedal down-up cycles did you do per wheel?
Did you also bleed the MC?
You say gravity method but the procedure also involves pressing the brake pedal. Please clarify.
Did you bleed the wheels in the proper order?
Did you route the bleed hose UPWARD over spring and back down into waste container?
How many pedal down-up cycles did you do per wheel?
Did you also bleed the MC?
#6
Re: Rebuild brake master cylinder or purchase a replacement?
Gravity feed is simply opening you bleeders and letting the brake fluid "gravity feed" for a few hours.
It's actually a really good way to bleed the system but you can't let the reservoir run dry.
#7
Re: Rebuild brake master cylinder or purchase a replacement?
Did you bleed the wheels in the proper order?
Did you route the bleed hose UPWARD over spring and back down into waste container?
How many pedal down-up cycles did you do per wheel?
Did you also bleed the MC?
That is not how you gravity bleed brakes. Sounds like a great way to suck air into the calipers.
Gravity feed is simply opening you bleeders and letting the brake fluid "gravity feed" for a few hours.
It's actually a really good way to bleed the system but you can't let the reservoir run dry.
Gravity feed is simply opening you bleeders and letting the brake fluid "gravity feed" for a few hours.
It's actually a really good way to bleed the system but you can't let the reservoir run dry.
Gravity feed consists of opening all of the bleeding valves, correct?
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#8
Re: Rebuild brake master cylinder or purchase a replacement?
If you're implying bench-bleeding the MC, then no I did not.
#9
Re: Rebuild brake master cylinder or purchase a replacement?
#10
Re: Rebuild brake master cylinder or purchase a replacement?
One additional step that I take when bleeding the wheels is to tap the caliper/wheel cylinder with a rubber mallet after the 10-12 pedal pushes. Surprisingly, the tapping often releases some bubbles that were stuck in the caliper/wheel cylinder. I then repeat the pedal pushes and tapping until the tapping no longer releases any bubbles.
#11
Re: Rebuild brake master cylinder or purchase a replacement?
One additional step that I take when bleeding the wheels is to tap the caliper/wheel cylinder with a rubber mallet after the 10-12 pedal pushes. Surprisingly, the tapping often releases some bubbles that were stuck in the caliper/wheel cylinder. I then repeat the pedal pushes and tapping until the tapping no longer releases any bubbles.
#12
Re: Rebuild brake master cylinder or purchase a replacement?
Update:
Ended up taking it to a dealership to get it done (thank you VW Goodwill Dealership card) and even after the brake service, the pedal does exhibit the same symptoms as before.
Out of curiosity, do faulty wheel cylinders also exhibit similar symptoms as well before they fail?
Ended up taking it to a dealership to get it done (thank you VW Goodwill Dealership card) and even after the brake service, the pedal does exhibit the same symptoms as before.
Out of curiosity, do faulty wheel cylinders also exhibit similar symptoms as well before they fail?
#13
Fish Twig
Join Date: Nov 2005
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Re: Rebuild brake master cylinder or purchase a replacement?
After driving it what color is the brake fluid? Also go ahead and inspect your cylinders and calipers for any leaks. Another thing is that if your guide pins are seized up it could also cause this smooshy pedal feel as well. Alot of things to look at, suggest you get started.
#14
Re: Rebuild brake master cylinder or purchase a replacement?
After driving it what color is the brake fluid? Also go ahead and inspect your cylinders and calipers for any leaks. Another thing is that if your guide pins are seized up it could also cause this smooshy pedal feel as well. Alot of things to look at, suggest you get started.
I can only conclude that it is the brake master cylinder that is faulty. Besides, for a 20 year old car, I expect the car to go out anyways.
It just sucks that I got the brake service done first only to find out that the brake master cylinder was indeed faulty.
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