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

 

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.

 

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).

 

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.

 

If you want to buy (or borrow) a Power Bleeder it will be easy to take the guess work out of it. It does a great job of getting all of the air out of the system much easier than the "normal" way.

 

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.

 

If you're going to buy one, spend the money and get this one: https://www.motiveproducts.com/

 

I have a Motive power bleeder and it's the dog's danglies, as the Brits would say. I bought the universal top and it can be a challenge to secure it to the reservoir. They offer a top that screws right on to the G reservoir making it easy peasy.

 

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.

 

I'll have a motive power bleeder for sale in the next week. I bought a second unit to use for pushing fluid into the diff and manual trans but wound up using a length of hose with a funnel instead. You'll still need the proper reservoir adapter.

 

I just sent the MC back on the premise that's not the problem as I did another round of bleeding and found plenty of air still in the lines. This time no low resevoir, but it still didnt fix the soft pedal. Since i need both front and rear pads im going to change those out and bleed again. Im not sure if maybe theres a bad bleeder nipple or what, but im not seeing any leaks or any noticeably bad lines, but theres still way too much air coming out. When i did the front driver side this time too some schmutz came out of the nipple. It's probably a big red flag the MC is bad, but right now id rather throw money at brakes i need and another bleed to try and resolve this than risk blowing 100 on an MC that didnt need replacing.

thanks all for the help.