Hey guys,

Long story short my master cylinder cap had a crack since I've had the car. I finally bought an aftermarket cap and gasket and replaced it and bled the system all 4. 4 way discs. The car stops better but when the pedal goes too far the brake light comes on until I push the pedal down far again

I'm now looking to the prop valve. There are no leaks and it looks good but it could be malfunctioning. What else could be an issue?

I may replace the prop valve , but what else could be causing it to stop slowly (can't lock up brakes but I can pump for more pressure)?

Thanks! I'm just trying to get this junk to stop pretty decent and not cause a brake light. And yes the pads are almost new, rotors are flawless, and wiring under dash looks good

 

Also the pedal does make a woosh sound

 

Sounds like they need to be bled again(air in line)

 

I may just take it to my mechanic tomorrow. Unfortunately I've run out of time to fix it (about to be hit by terrible snow) and then after I have to make a long trip.

 

I second the still air in lines. How did you bleed it? Was it run dry then bled traditionally from all fours? Did you end up bleeding the master separate? I've seen them become air bound is why I ask.

 

I have not bled the master cylinder. I forgot that.

I bled farthest from the master and inwards and didn't bleed it dry. Pumped it up, bled out the air filled fluid and closed it off. Topped off master and onto another brake

 

Damn, was hoping you ran it dry at some point and maybe my question could have been of some help. If it was air filled, it could have gotten a little air bound tho?

 

I'm not sure about that, it seems good. I'm nearly a 100% sure the master cylinder needs to be bled. With a broken cap for that long it makes sense

 

Worth a shot I'd imagine. Or just keep on pumping and holding. Lol. I had a trailblazer the other day do this but, I ran the master dry after the first caliper. Fluid was nasty...

 

Can't bleed the MC installed on the car.

It's at such an angle that the fitting for the line isn't at the highest point. IOW, a certain amount of air, once it's in there, can NEVER be bled out. It just stays up there at the top.

Gotta "bench bleed" it. Which can be done with it somewhat on the car; take the nuts off that hold it on, move it forward enough that it can sit closer to level, take the cap off, have your assistant poke with very short strokes at the piston with something non-metal (so you don't chew it up) until air quits coming out of the holes at the bottom of the reservoir.

 

Took it to my handy shop that I trust since its been 18 and icing out. They bled the entire system and put in all new fluid. The old fluid was over its time in the car just by the color. After a bleed the brakes have returned to their former glory of mediocre haha.

 

Did they "bench bleed" the MC?

If not, the air that was in there before, is still there.