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1999 Mazda Protoge Brake issue (no brake pressure)
Hello All,
I want to ask your opinion on failing brake pedal pressure. A friend asked me to work on his vehicle after he replaced a brake line and the brake master cylinder With a brake booster because he could not get any pedal pressure. He went to an auto salvage and picked up those parts and put them on. When it was brought to me, I replaced the master cylinder with a new one thinking the used one was weak which I noticed the different pressure between the two as I was hand bleeding it before going into the vehicle. Once bled by hand and also while in vehicle, I bleed the lines twice starting from RR, LR, RF, LF and still has no pressure. I have never had one with this problem.
This vehicle has no abs, so I found out it has a proportioning valve. My concern is, how do I know if it's bad or should I bleed that after bleeding the master cylinder before doing the wheels? I wonder if this is my problem.
Also when applying brakes with vehicle off, the brake pedal builds pressure and when you start the engine it goes down, so I know the booster it's not the issue here other than he has a fuel rubber hose from booster to engine vacuum. One thing I also noticed, there is no check valve between the vacuum hose line and booster, I’m thinking it needs one and will call dealership to find out if it requires it. Perhaps maybe this could be part of the problem.
