Help with brakes

[heep70]

I need suggestions on my brake problem. It is an 86 wagon disks on all four corners, new pads, new MC. I must have bleed a gallon of fluid so far and I am bleeding them using the "x" pattern. No fluid lose at all. Callapers are working and do no leak.

 

Here is the deal. The car stops, but I can, with not much force, push the peddle down to the floor. Even when i pump the peddle I can still push it all the way down. The amount of force is just with the toes of my foot.

 

I am now pointing my finger at the power assist diaphram.

 

Anyone else run across this problem?

[thealleyboy]

Greg: Not sure about the power assist. If it were out, it might actually give you a "harder" pedal feel.

 

Question: How much pressure are you getting when you are bleeding the brakes? Does it go all the way to the floor then too?

 

My guess is the master cylinder. (yes, I know you said it is new!!) Without any fluid leaks in the system, you have to consider the pressure getting to the calipers, and that would be the MC.

 

good luck, John

[iluvdrt]

did you bench bleed the master cylinder? i know its not that important, but it will take longer to bleed them other wise. also try doing it this way

passenger rear, driver rear, passenger front, driver front.

 

typically you always want to start with the one farthest away and work closer. if not gravity bleed. if that doesnt work, there is an open in the system.

[heep70]

I checked the booster and it is OK.

 

Yes, the thought of the new MC being bad is in my mind also. I have had bad MCs that leaked back on my Ford. Nothing like this. Usually I can pump the pedal hold it and feel it go down. This one you can pump it and just push it right down without much effort at all. It was the same way with the old MC.

 

To give you and idea of the amount of pressure it takes to push the pedal down. It takes the same amount of force as when I bleed them. It is like there is a bleeder open.

 

When I bleed the brakes the pedal does go all the way to the floor. There is pressure.

 

The only different method I have not tried when bleeding is to turn the car upside down.

 

Yes, I also bench bleed the MC.

 

Thanks for the repies

[calebz]

Check the little areas where the brake lines are flexible/rubber.. they can get old and expand when pressure is applied.

[robm]

Does the fluid level drop when you push the pedal down? Do it repeatedly, and see if it does.

 

If it drops, you have a leak. By this time, it will be obvious, like a big puddle on the floor. Rusted out brake line, or bad hose? Have you checked those yet?

 

If it doesn't have a leak, then it might be a really poorly rebuilt MC, like they forgot the seals!

 

However,you said it did this before the new MC, so I think a leaky line is more likely.

[heep70]

No fluid lose or leaks found anywhere.

 

Nice thought on the rubber hoses. I will check that next.

[SubSandRail]

I have not done a soob MC, but I just helped a friend with his 67 beetle, and the master cylinders are similar. We had the same problem, and we had to bench bleed it several times before we figured out that you have to get fluid between the two pistons in the master cylinder. When you press the brake pedal, you push in the first piston, which pressurizes one set of brakes, but it also pushes the fluid between the pistons to activate the other set of brakes. If you have air between the pistons, it is just like having air in the lines.

 

Hope that helps.