Why am I still not able to bleed my brakes? part 2?

Question

(99 malibu). I still cant' get my brakes to bleed. I followed the suggestion about bleeding @ the master cylinder. The Front brake line (which I'm assuming goes to the front brakes) did fine. plenty of pressure after having someone pump the brakes up. As I mentioned in my last question, back brake bleeder valves are getting no fluid to them (tried pumping and gravity bleed). So when I tried to bleed the back line at the master cylinder (which once again I'm assuming goes to the back brakes) I'm getting no pressrue. At best I'm getting a couple of little drips out of it after opening the line up (after having someone pump the brakes up). Is this leaning toward being a master cylinder problem? plenty of pressure out of the front line at the master cylinder, but none out of the back line. at the moment the $90 for the new master cylinder is hard to come by, so I want to try and make sure that is my problem before investing the money. Thanks for everyones help!

ive had a couple of people mention the proportioning valve. But isn't the proportioning valve located after the master cylinder. I tried bleeding from the master cylinder it'self, and am not getting any pressure from the back break line at the master cylinder itself. I'm getting plenty from the front line at the mc, but none at the back. Only a few drips.

i started out bleeding at the wheels, but wasn't getting any fluid in the back., so I took sugesstions and tried to bleed at the master cylinder to see if I was getting pressure from there. I'm not. so it' s not a clog in the line. I'm not even getting any pressure for the back from the master cylinder.

Answer 1

First, why were you bleeding at the cylinder? when you bleed, the purpose is to remove the contaminants in the lines, such as air. You need to bleed at the wheels.
If you aren't getting and fluids out of the bleed valve, there may be a clog, or there is no fluid in the reservoir/cylinder (assuming there is pressure on the lines).

Answer 2

On most systems the front line from the master cylinder goes to the rear brakes and vice versa. If you're not getting anything from one line at the master then it probably is the master cylinder. However, since you're getting fluid from the front fitting but not from the rear wheels there maybe another problem. Could be bad bleeders or bad wheel cylinders. Brakes should be bled until new (clean fluid) is coming out at all four bleeders every year or two. Brake fluid attracts moisture which, unfortunately, will rust the cylinders and destroy the seals, overtime. Best way to prevent it is have the system flushed on a yearly basis. Try to find a garage which has power flushing capability. They connect a source of fresh fluid, under pressure, to your master cylinder. When the bleeders are opened it forces clean fluid through the system and eliminates the slow pumping and bleeding cycle. If you have a front disc rear drum system there will be an equalizer valve in the system which corrects for the different pressures needed by drum and disc wheel cylinders. That could also be causing the problem.

Answer 3

When i have a bleeding problem i open and fill the master cylinder,open all bleeder valves and leave the top/cover on the master cylinder off. If that doesn't work you might have air at the proportioning valve, if you do you'll have to bleed it . It sounds like you have an air lock/bubble somewhere and all you have to do is bleed all the fittings all the way back to the rear brakes.If you have anti lock brakes bleed at module. Hope this helps...Steve

Answer 4

First take off master cylinder, then fill master with brake fluid,

Get yourself one of them bench bleeding kits at your local auto store,Take metal rod or screwdriver and insert in end of master cylinder.

Now as you hold tubes so bled fluid can return to master, Push screwdriver in to actuate plunger on master cylinder.
Push slow, once air comes out release. Repeat process with 7 second intervals.

If you are still not getting nothing out of your rear cylinder you can eliminate the porportioning valve, therefore a new master cylinder is in order.

If you get a new master cylinder follow the bench bleeding instructions I provided.Once you get a master cylinder that has equal pressure out both reservoirs, Then install master, hook up lines and proceed to bleed brake system at porportioning valve.

Once you eradicated all air then move onto passenger rear , drivers rear, passenger front, & finally drivers front.

Hope this helps..................

Answer 5

remove the master cylinder and bench bleed it using metal or plasic tubing, screw the line fittings in the master cylinder, bend the tubing back into the reservoir keeping the open end of the line submerged at all times, and pump, pump and then pump some more. If you don't get results after fifteen minutes or so, replace the master cylinder.

Answer 6

if you are not getting anything at the back lines then yes the master cly is the problem. that will have to be replaced. but when you get the new master cyl. you will have the bench bleed that master cyl. before anything else is done it comes with inst. on how to do it .and onc ethat is done and installed then you bleed the far wheel from the master cyl.which will be the passenger side rear then the driver side rear and the the passenger side front and then the driver side front make sure you have lot os dot 3 or dot 4 break fuild

Answer 7

You sound like you could need a new proportioning valve. It is what allows the correct amount of pressure to the rear wheel cylinders. I would look into that first.......**If it is only serviceable by replacing the master cyl. be sure to "prime" it first. There should be instructions in the box. If not refer to a decent parts dealer or shop.

Answer 8

With abs brakes you need to run the car while bleeding so the pump will put fluid on the rear start over and start on the right rear and then left rear, then front r/f l/f hope this helps.

Answer 9

many ABS equipped vehicles require a scan tool to bleed the brakes, there is a function in my Snap On scanner to put the ABS system into a bleed mode.

Answer 10

IF IT HAS ABS BRAKES YOU WILL NEED A SCAN TOOL TO PUT THE SPOOL VALVES IN THE ABS IN A NEUTRAL POSITION