how likely could my brake master cylinder have failed?
#1
Registered User
Thread Starter
how likely could my brake master cylinder have failed?
Dealing with a soft pedal that when under moderate pressure will eventually sink to the floor. It has a long throw on first push, but a quick pump will bring it to a solid and short throw. Seems like a common issues from my research, but the solution is usually a fluid flush or 4 wheel bleed. I dont have any issues with braking besides that and it's not sinking to the floor while im stopped at lights or in traffic.
I just did a complete fluid flush and bleed of all 8 bleeder nipples and it hasn't solved the problem. There was def air in the lines and i only did one short road test so it's possible theres still air in the lines, but the fact the pedal goes to the floor makes me think its the MC. I just haven't read a lot about the MC failing and i only have about 87k miles on the car. I didn't notice any leaks or anything obviously broken with the brake lines, but i do plan on doing a second more thorough inspection as well as another round of bleeding.
thanks for any help
I just did a complete fluid flush and bleed of all 8 bleeder nipples and it hasn't solved the problem. There was def air in the lines and i only did one short road test so it's possible theres still air in the lines, but the fact the pedal goes to the floor makes me think its the MC. I just haven't read a lot about the MC failing and i only have about 87k miles on the car. I didn't notice any leaks or anything obviously broken with the brake lines, but i do plan on doing a second more thorough inspection as well as another round of bleeding.
thanks for any help
#2
Lexus Defector
iTrader: (60)
From our sampling here on the forum I wouldn't say this is a frequent or common problem with our cars, but it's certainly possible. You are already on the right track about flushing and bleeding. Make sure you have clean fluid and that ALL of the air is out of the lines. If you had really dirty fluid or there was black grime on the bottom of the reservoir that could possibly indicate a MC problem. The black sludge is from the seal material that has been worn away and accumulated there.
#3
Movin On!
iTrader: (13)
Is it possible you got air into the MC during your last bleed? If so it will take much more bleeding to get the air out.
Also, was this problem going on prior to the latest work you performed? And did you bleed in the order as per FSM (passenger rear, driver front, driver rear then lastly passenger front).
Also, was this problem going on prior to the latest work you performed? And did you bleed in the order as per FSM (passenger rear, driver front, driver rear then lastly passenger front).
#4
Registered User
Thread Starter
Fluid didn't look nasty and there's def no black grime or sludge in the reservoir, but yeah it's possible the fluid got too low as well. I did the bleed in the proper order, but doing the first passenger rear the fluid hit bottom. It wasn't bare and it looked like it still had some fluid so i topped it up and kept going. The issue was there before this work which is why i was doing the work.
#6
Registered User
Thread Starter
Owning 3 cars i probably should have one already, but they always seem to get mixed reviews and many require special adapters per car. I plan on getting to this sunday so maybe ill take a trip to harbor freight and see about getting one.
#7
Lexus Defector
iTrader: (60)
If you're going to buy one, spend the money and get this one: https://www.motiveproducts.com/
Trending Topics
#9
Registered Member
Sounds like the MC since you bled the system. They do fail, but not often if the fluid is serviced every two years. What I have seen is that the MC plunger seals becomes worn-tho a friends RX7 the plunger tube had rusted and damaged the seals-he never serviced the fluid; moreover, he had a lot of air in the system which I didn't know where that came from since we couldn't find any leaks.
Luckily it's not the ABS else there would be a warning light. By the way, Nogoer is correct with his bleed pattern as that is required by ABS systems-surprising is most pro mechanics do it the old way of furtherest to the closest which makes for a kinda soft pedal. Anyway, I use a bleeder sucker and have the wife do the pedal pump-makes a really solid pedal.
Luckily it's not the ABS else there would be a warning light. By the way, Nogoer is correct with his bleed pattern as that is required by ABS systems-surprising is most pro mechanics do it the old way of furtherest to the closest which makes for a kinda soft pedal. Anyway, I use a bleeder sucker and have the wife do the pedal pump-makes a really solid pedal.
#11
Registered User
Thread Starter
thanks all for the help.
Thread
Thread Starter
Forum
Replies
Last Post
Juscus
Brakes, Suspension, Wheels & Tires
24
05-21-2016 08:17 AM