Brake bleeding problems with 1997 Taurus

[cjhepburn]

I'm having problems getting all the air out of the brake system after I replaced the two brake lines from the proportion valve to the rear of the car. It's a 1997 Taurus, nothing special.
I've probably have gone through about a gallon of brake fluid at this point. So far I've tried bleeding the furthest caliper to the closest. I did this several times and it's still spongy. I also tried bleeding diagonally with no luck.
What am I missing here? I'm pretty good with cars but this is the first time I have not been able to get the air out.

 

[chad8]

You probably have a bad master cylinder. Its letting air in to the system.
Are you using a vacuum pump like a mity vac or are you pumping the brake pedal?
That could be the issue too.

 

[cjhepburn]

I forgot to mention that I replaced the master cylinder too but that didn't change anything. I'm just pumping the brake pedal. Would Mity Vac do a better job?

 

[NHGUY]

A Motive Products pressure bleeder would do it.

 

[yonyon]

It's possible that you have a small leak somewhere. The pressure bleeder NHGUY recommends would also help with finding that.

 

[Merkava_4]

When you replaced the brake hoses, did you replace the banjo washers?

I've been there and done that. I couldn't figure why I kept having air in the system after bleeding the brakes several times. I finally gave up and took the car to a repair shop. They found fluid leaking around the banjo bolts and the solid brass hose blocks. They asked me if I used new banjo washers before putting the brake caliper hoses back on. "You're supposed to use new washers?" I replied. The mechanic then showed me a scratch in one of the banjo washers. I was stunned to find out that fluid could leak out and consequently, air could get in that way.

 

[Tegger]

Originally Posted By: cjhepburn
I forgot to mention that I replaced the master cylinder too

Did you bench-bleed the new MC, or just throw it on dry?

Do you have rear discs? If so, do the calipers incorporate a parking brake, or is the parking brake separate from the caliper (drum-in-hat, etc.)?

Has a mallet been employed at any point at any location during the bleeding sequence?

 

[yonyon]

Come to think of it, there are some very important questions that might help with the thinking here:

-disc or drum brakes
(Tegger: if they're discs the calipers have the parking brake integrated)
-sedan or wagon? This matters.
-with or without ABS?
-Why were the brake lines replaced?

 

[Tegger]

Originally Posted By: yonyon
(Tegger: if they're discs the calipers have the parking brake integrated)

If the calipers have an integrated parking brake, then they are notorious air-traps. This is, in part, where the mallet I mentioned comes in.

 

[cjhepburn]

I don't believe there are any leaks, the reservoir stays at the same level.
It's 4 wheel disk brakes and not sure if it is ABS. 1997 Taurus sedan, the most common one; 3.0L EFI. It's my father's car, I'll check it tomorrow when I'm back at it. What are the consequences for it having ABS?
The calipers have the parking brake integrated.
The brake lines were replaced because one burst due to corrosion and the other looked bad as well. I didn't replace the caliper so no need for banjo washers.

 

[andyd]

Open the top of the MC top it off with brake fluid. leave the top off. Now use a dry towel on every connection you have worked on. Find a wet one and you have found a leak. When I replaced the hard lines and hoses on the Rat, I must have found 3 or 4 drippy unions when I started to bleed. By the time I was done, I had a great pedal.

 

[SHOZ]

Start the car and let the power assist help. There is a proportioning valve in the back on the drivers side that will reduce the flow to the rear brakes if the wheel is off the ground. The power assist helps get around this.

I use to pump them while the bleeder was cracked open a 1/4 turn and a clear hose that clamped to the bleeder screw and was immersed in a bottle of fluid. Once I was done pumping I would keep the brake pedal down with a board between the drivers seat and the pedal.

 

[cjhepburn]

I tried one more time using a MityVac; no air came out. There are no leaks. I've bled brakes probably a couple dozen times in my life and I've never been unsuccessful until now. The car does have ABS and I think that has to be the culprit. I don't have the diagnostic tool to open the valves in the control unit.
I've got a total of about 15 hours into it and I hate to be beaten but I think it's got to go to a mechanic.
Thanks for your ideas anyway.

 

[SHOZ]

When replaced the lines on my '97 Taurus I disconnected the two lines from the MC to the ABS pump and bent them up so the fluid would not drain from the MC. Then replaced the ones connected to the ABS pump. The pump should not have air in it if it did not before hand.

But, try going out on a gravel or dirt road and do several quick full stops that engage the ABS. Then come back and rebleed.

 

[cjhepburn]

That's one of the suggestions from above. I tried that as well and got the ABS to engage several times on a gravel road before I started the bleeding process. No change to the pedal.

 

[AVB]

How does it stop and how did the pedal feel before the line burst? Some systems just have weird feeling pedals if you are not used to them. Does the pedal pump up firm with the engine off?

 

[SHOZ]

Originally Posted By: cjhepburn
That's one of the suggestions from above. I tried that as well and got the ABS to engage several times on a gravel road before I started the bleeding process. No change to the pedal.


I'd go over to the Taurus Car Club of America and ask. I know I've seen this problem solved.

TCCA forums

 

[cjhepburn]

The pedal was firm before. Now you can pump it up and it feels firm but it slowly sinks to the floor. I checked the Taurus forums and it does appear that you need to activate the ABS in service mode. I don't have the code reader that has that functionality.

 

[AVB]

Slowly sinking to the floor sounds more like a leak or bad component than air in the system.

 

[andyd]

Originally Posted By: AVB
Slowly sinking to the floor sounds more like a leak or bad component than air in the system.
. YAH sounds like it to me too. Does a 97 have drum brakes? If so maybe they need adjusting. Other,than that, if it had a good enough MC to pop a rusty line, then the MC is still good. I have done plenty of brake lines and stuff up here in the Rustbelt. If you havent let the MC go dry, the ABS shouldn't be involved. That just leaves what you were working on. I don't want to bruise your tender ego but. When ever I fix something and it doesn't work, I check out my work. Because history has shown that I'm capable of scrweing up. I know, I was amazed to learn I wasn't perfect too