bluemp301

iTrader: (5)

I just installed a brand new brake master cylinder from mazdatrix and bled my brakes. Everything looks great and is getting fluid at all 4 wheels but the only problem is the pedal will still go to the floor. When the brake pedal is being depressed and its near the floor there is also a hissing sound coming from somewhere behind the intake manifold and I can't seem to find out where its coming from and I'm 99% sure this is my problem. It has the same affect with the car running its just louder. I was going to try to use some soapy water and find the leak or a missing hose or something I'm just needing a reference point. The only line I'm seeing is the one running from the brake booster and plugs into the intake manifold. Also this is a non-abs car.

AmT_T

iTrader: (11)

do you have the check valve installed in the vacuum line to the brake booster? is it installed the right way? arrow pointing away from the booster.

this vacuum line runs to the solid line on the LIM make sure it's connected that might be your problem

bluemp301

iTrader: (5)

I just checked and I just have hose running between the hardlines of the brake booster. Work of the previous owner although everything appears to be in the correct location. Sounds like my problem. Well in that case is there a certain check valve I need or can I just run to one of the local parts stores and just buy a check valve? Also does it matter where the check valve is installed on the line or is anywhere fine as long as its pointing in the correct direction? I Appreciate the help!

clokker

iTrader: (2)

A check valve is a check valve...any one will do.
It doesn't need to be internal (like the original) nor does placement in the hose matter.

bluemp301

iTrader: (5)

Good deal. That's what I figured I just wanted to make sure. Heading to the parts store now! I'll update my findings after install. Hopefully this solves my problem.

AmT_T

iTrader: (11)

personally i dont think it will be the check valve. it points towards the manifold because that is the direction of flow. it opens under vacuum closes under boost. have you driven your car yet. usually after working on your brakes you will not get proper pedal pressure untill you use them. if you do this please becareful as they may NOT work!!!

Im a little stumped as to this noise.

bluemp301

iTrader: (5)

Well no luck finding a check valve in the size I need after checking all the major autoparts stores. Does anyone know of a place to order one from online? I have 5/16" hose on the line that connects to the LIM from the brake booster hardline but all the check valves I found were too small and 1 that was too large.

I have only driven my car a very short distance down the street and back after bleeding the brakes not coming out of first gear and using the ebrake gently to stop and they don't work. I have brake pressure but its not 100% and the pedal still goes to the floor and I'm thinking its due to whatever this noise is that sounds like an air leak. It just makes a very short hiss(think of an air pump on a basket ball) and nothing seems to be leaking anywhere so I assume its vacuum related based on its location. I could try to post a video but I figure I'll give this check valve a shot first. The car hasn't seen the road in about 8 years so this isn't something that just happened.

clokker

iTrader: (2)

A junkyard would be loaded with suitable checkvalves...any Japanese car would be a likely donor.
I'm not sure what this noise you hear might be but it's irrelevant at this point.
With the car turned off and no vacuum on the booster at all, the pedal still should not go to the floor...the brakes should work, just be very stiff.
Since you haven't mentioned it, I'll assume you're not losing fluid.
Have you tried adjusting the pushrod?

bluemp301

iTrader: (5)

I solved the noise problem. I took a piece of the line off to go match it at the parts store and I put it back on so I'm assuming it was a little loose at one of the ends. I have to go to work so I unfortunately won't have any more time today to mess with checking the rest of the connections but I'll double check them just to rule anything out. I'm not losing any fluid and reservoir is completely full. I have not adjusted the pushrod but I could give it a try. I'm just puzzled as to why I'm not building the rest of the pressure I need if everything has been properly bled. I'm willing to try/test anything you guys think it could be. Is there a write up somewhere for the pushrod adjustment?

clokker

iTrader: (2)

Not to be a dick or anything but why, after your adventure with the hose, would you assume the brakes are properly bled?

Anyway, as for the pushrod adjustment:
For the first step, we're only interested in seeing if you can get a "normal" feeling pedal, one that doesn't go to the floor.
Loosen the locknut at the clevis and crank in some preload, rebleed the brakes, see if the extra piston sweep dislodges some trapped air.
Did that help, does the pedal feel better?
If so, excellent...but DO NOT drive like this.

Go back to the clevis and take out the preload, go overboard and make the pedal loose again.
You should still have brakes, just way down at the floor.
Now drive the car, no need for speed or braking, just enough distance to heat the pads/fluid up to normal operating temp (a few miles around the neighborhood will do).
Stop and go back to the clevis, adjust so there's about 3/4" or so of freeplay before the brakes begin to actuate.
Tighten the locknut on the clevis and you're done.

For the next few days pay attention to the brake pedal/freeplay...you can fine tune as necessary, the whole point being that there is always some freeplay when the brakes are hot so they don't drag.

Get it wrong and the brakes can lock to the point that the car won't move...which can be embarrassing.

vrracing

iTrader: (1)

For the check valve you can get a W0133-1637053 ATE Power Brake Booster Check Valve for a 1985 BMW 528e from AutoPartsNetwork.com for $11.50. Its actually used on a lot of German cars and is made in Germany if that matters to you. Normally the checkvalve is hidden in the rubber line that goes from the hardline to the brake booster. You should be able to squeeze the line to see if its there.

But you dont have a brake booster problem. If the booster isnt working when you press the brake pedal to stop the car it will feel like you're trying to move a 2 ton boulder. You likely have massive amounts of air in the system. Air compresses - brake fluid doesnt.

I am guessing you didnt bench bleed the new master cylinder and there is still air in there. Google "bench bleed master cylinder" for more info than you could ask for on the subject. From the first hit...
Alternately, you can put your car up on jackstands, have someone press the brake pedal and see if the four wheels are locked up tight. If one is turnable then that line has air.

When you bleed the brakes you want to start at the farthest wheel (right rear) and systematically move to the wheel closest to the master cylinder (the left front).

Good luck.

bluemp301

iTrader: (5)

Clokker-I went to my neighbor who is a old hotrod guy and put my car on his lift and we bled the brakes. Started from the rear and moved to the front (longest lines to shortest lines) although I didn't bench bleed the master cylinder when I put it on as my dad said it would be fine without doing that. I assumed that whatever was causing the problem was associated with that noise and I assumed the air in the master cylinder would have been bled out when I bled the brakes but I appear to be wrong.

vrracing-thanks for the part info!

Sounds like I need to remove the brake master cylinder, bench bleed it like I should have the first time, and then re-bleed the brakes and go from there.

I appreciate the help guys. First time I've ever done anything with brakes.

clokker

iTrader: (2)

This advice is based on old tech, I do believe.
There is no connection at all between the front and rear brakes, so it doesn't matter at all which one you bleed first.
As for "furthest>closest" within the subsystems...meh, I never found it to make much difference either way.

You needn't remove the MC, in fact, usually just cracking the lines that screw into it and slowly depressing the pedal (once!) will do the trick.

A few years ago when I was swapping out MC/boosters nearly every other day, I never bench bled the MCs or bled in the recommended sequence (passenger rear to driver front) and had no problems at all...even working by myself.

Speed bleeders on the calipers help though.

vrracing

iTrader: (1)

The sequence is probably meant to systematize the process so drunken noobs dont miss a wheel!

clokker

iTrader: (2)

Darwin would approve of working on brakes while drunk...

beefhole

iTrader: (29)

^Just be sober when you test them!
You just didn't bleed the brakes enough the first time, that's all. Do it again!

misterstyx69

iTrader: (142)

check valve. NO.that is not the problem.
If it was backwards you would have to have a leg like an elephant to stop.
Rebleed your brakes.