So here's my noob question for the day (month, year?):

After rebuilding one of the rear calipers (did the other side without problems), I let the brake fluid get too low in the master cylinder. So I have air in the system.

The pedal was going all the way down and I had to pump the brakes a 1.5 times to get the car to stop.

I bled the caliper and it seems no more air is coming out on that corner. It's much better, since I don't have to pump the pedal anymore, but the pedal almost goes all the way down.

I know the brake system is split front left, front right, and rear. I'm planning on bleeding at all four wheels (rear right, rear left, front right, then front left). But will this get rid of all the air?

Do I have to bleed the master cylinder? (i.e. loosen the brake fitting at the m.c.) Or will the air eventually get out?

Thanks all.

 

The Fronts will get the Air first i have noticed in my S4.. If i ad some brake fluid could be small amounts of air.. But they somehow work its way back to the top. Just have a friend help ya pump the brake as you blead from the top.. See if that works. If not bleed the front calipers.. Then drive around. Make sure the two rear wheels and front wheels are about the same TEMP so you know they are working evenly

 

Forgot. If your fluid is Low then its leaking somewhere. Sometimes it leaks from below the Plastic peice. It might need a new gasket. the rubber gets loose and it leaks.. make sure its dry

 

Maybe I wasn't clear. Everything is sealed. Air got in because I was bleeding the caliper and let the master cylinder reservoir level go too low.

Will bleeding at the calipers eventually get rid of air that entered through the master cylinder? I wanted to avoid bleeding the m.c. if possible.

 

It should.

 

Just start from scratch and bleed all 4 calipers.
Your MC should be fine.I've done what you did before...helps if the guy pouring fluid in is actually watching it..not in LALA land..(toast?..hmm..what is this in my ear?scratch..)..LOL!

 

I have.some brake pressure.issues.as.well. I have bled.all 4 corners on mine about 7 times. I think i will.end up having.to bleed the master.

My pedal feels.like it has no pressure at.all and pedal is.so.soft you would think i had no brakes at.all. My pedal goes in about 90% down without any pedal feel or braking till the pedal almost hits the.floor then the car brakes out of nowhere.I dont get it. I also have new brake booster. :/

 

You could gravity bleed it if you wanted to be lazy, but the main thing for when you are bleeding your brakes is to make sure that your resivior has enough fluid in it.

Bleed the Rears first, then the RF-LF calipers.

Vacuum bleeding is probably the easiest to handle, 15$ tool at harbor frieght, attach a hose to the bleeder screw and pump away till you see no more air bubbles.

Key is to keep fluid in the resevior.

 

You may be having issues with the pushrod adjustments.
There are two...the connection from the pedal to the booster and the booster to the MC.
Both are adjustable, I'd try the pedal to booster first.

 

I'll try bleeding the calipers in the right order (did the rear left only before). If that doesn't work will bleed the m.c.
For the record...what are the sizes of the m.c. line fittings?

 

I've bleed brakes on mazdas literally hundreds of times and not once have i had to bench bleed the MC. Just bleed the corners once around then bleed them once around again. You should be good to go.

I have heard that the FD master sometimes needs bench bleeding. But ive never had that problem with one.

 

10mm x 1.0, inverted flare.

 

When I bought my car, the brake fluid was black...yes Black. It had to have been as old as the car.

I took me 3 quarts of brake fluid to get all of that nasty **** out, I have never seen anything like that.

This is the proper bleeding procedure...

1) Passenger rear caliper
2) Driver side rear caliper
3) Passenger front caliper
4) Driver side front caliper.

After that (I am not surprised) my master cylinder let go, and i had to bleed it, and the entire system again!

Used another 3 quarts that time to get all of the air bubbles out, and there was still some black ****. O_o

Be sure to take your time, bleed. bleed, bleed, until every last bubble is out.

 

The reason you bench bleed a master cylinder is so you don't pump air down the brake lines. If your master is working, then you have merely pumped lots of air into the lines.

Bleed 'em. Bleed 'em all.

 

I did a bench bleed of the MC, but I went ahead and bled the brake system again and was shocked by all of the nasty **** still left over.

 

It's amazing, isn't it? Fluid in my 90 vert was nasty, but the worst I ever saw was a 250,000 kilometer Canadian S4 n/a I bought. I turned a 1-liter bottle of fluid upside down in the master cylinder and just kept making the rounds. I bled it till the fluid was clear. I used the whole bottle.

 

Lol! Thanks all for the info and clokker for the spec.

 

This is why you should completely flush the system once a year (at least).
It's not often mentioned -but especially pertinent if you don't frequently drive the car- that brake fluid is very hygroscopic...it loves water and will absorb lots of it from the vent to atmosphere in the reservoir cap.
You can rust out the hard brake lines if left sitting long enough.
(This is why DOT5, i.e., silicone, fluid is popular with show cars as it won't absorb water but it doesn't perform as well either)

Absent outright rust issues, the absorbed water will lower the boiling point of the brake fluid and degrade performance.

Water will turn the fluid cloudy but the black you might see is actually from the various seals in the system degrading. When I see black fluid, I just assume everything will need a rebuild.