HELP With Brakes.

[Grantkat]

follow on to that - looks like I am upgrading my scan tool.

[454cid]

I would suspect the flexible brake hoses if fluid isn't coming out in a normal manner.

On my truck the ABS isn't in the loop unless activated, so I never mess with it when bleeding brakes.

[Grantkat]

Interesting....

so would a valid test be: disconnect the flex line from the hard line and see if I get flow at the hardline/flex line point? assuming the flex line is the issue, i would assume that I would get a good flow of brake fluid at that point if the flex line is the issue.

Although possible, why would 3 go out at once? just coincidence via age etc?

[ZionXIX]

Yea, just pick one wheel and work your way up from the caliper to each connection until you get good flow. All flex lines are known to degrade internally and cause all sorts of issues.

[MoVolvos]

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Have you tried bleeding the system with the car running. This is my new way bleeding brakes after a brake job. Have car running and press down while releasing the bleeder screw. Since the pedal is already going to the floor just loosen and then press down. You have to do all 4 in order to compare flow.

Obviously, this is a 2 person job but comparing all 4 can give you some idea where the problem might be. For instance if all 4 have no flow that means it's not in any of the system / lines out of the ABS module. From reading some of the forums this is a problem many encounter so could be a manufacture defect as in our P80 ABS modules.
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[454cid]

Interesting....

so would a valid test be: disconnect the flex line from the hard line and see if I get flow at the hardline/flex line point? assuming the flex line is the issue, i would assume that I would get a good flow of brake fluid at that point if the flex line is the issue.

That's what I had to do with my truck. I was getting almost nothing out the line disconnected from the caliper, and then after removing the flex hose, it suddenly flowed.

Although possible, why would 3 go out at once? just coincidence via age etc?

I hear that the flex lines can break down inside creating blockages. Maybe they've been bad for awhile but with introduced air there was enough of a cushion in the lines that the pressure was never great enough to push past blockages?

[volvolugnut]

If the brake fluid is old, it can really get to be sludge. And yes, hoses go bad on the inside. I replace hoses if I do a brake flush job on 20+ year vehicles.
volvolugnut

[Grantkat]

symptom: Pedal goes to floor with car off and with car on.
OK here is an update:
The Master cylinder is good - tested
The brake booster is good - tested
bleeder screws/calipers eliminated as a potential problem

Brake lines are solid - no corrosion
Flex lines seem good - I say this because I was able to push fluid through them manually by pumping fluid through one end I got fluid flow to the other. The difference being it wasnt a sealed system under pressure.
I removed and tested the bleeder screws and removed the banjo connection at the caliper - this eliminates a plugged or bad bleeder screw and eliminates the caliper as potential issue

now here is what I have:
Rear brakes show some fluid movement when pumping brake pedal - you can build some pressure and when you release you get a squirt of fluid - I would not characterize it as a normal flow. you can also pump the brakes with the bleeder screw open and get some fluid - again nothing of a normal flow.
Front brakes zero fluid no mater how much you pump the brakes.no fluid at the screw, no fluid with the caliper banjo bolt removed, no fluid at the hard line.

I attemped to disconnect one of the input lines to the ABS pump it is a hard line directly from the master cylinder. it is in a difficult location and I decided not to tempt fate.

at this point I am thinking it has to be at the ABS pump.
I am considering upgrading my scan tool to one which will manually bleed the ABS pump. the cost of the tool itself is less than a service visit to my mechanic of choice.