98 Windstar w/trac control soft break pedal

My wife has a 98 windstar with trac control and we are having problems with a soft break pedal. We took it to Midas they said is was the master cylinder but 3 days and 6 master cylinders they were baffled (lucky for us they didnt charge us). But now I'm baffled I usually can fix anything on the vehicles but this just isnt making sense.:banghead: If anyone has any info or has had this happen to them I really could use some input.

Thanks in advance!

I am guessing that they gave the brake system a good bleeding....most likely several times.
If they found air in any line......it could be a leaking piston in a caliper, wheel cylinder, or bleeder valve, etc.
Of course, one would expect brake fluid to also leak out at that point also...which would lead them to the problem.

I remember a post about a check valve for the power boost unit (that the master cylinder is mounted to).

OK.....GARYNC1 gets the credit for this......I just lifted this out of another thread.

Check valve is....
"the little black part where the hose plugs into, then plugs into the booster.
................. lets air flow when needed but keeps it from loosing air back into the system..
Just like a foot valve on a water pump...
Trust me!!change that little round plastic part first.
Go to the Auto parts store and ask someone who knows, most all have them.
But they act like they don't know what you are talking about when you asked them.. Drives me crazy sometimes. If that does not work then replace the booster. But I think you may have some luck with this..It the Round Looking thing that plugged into the booster and the hose follows that... "

Hey thanks for the information, I will be checking on that as soon as I get home from out of state, I'll post and let you know if it worked!

OK... so I replaced the check valve and still nothing pedal still goes straight to the floor. Any other ideas on this? Starting to get frustrated with this thing. THANKS!!!

Feeling your pain: I have a '98 GL w/126k, ABS, traction control, and a soft brake pedal.

Replaced rear wheel cylinders, rear spring hardware, rear drums, front calipers, front rotors, front caliper bolts/pins, spring clips,
and brake booster check valve. And replaced old caliper bolt grease w/synthetic high temp.

Flushed and replaced brake fluid with high temp synthetic and had system professionally bled. And bled it myself at each
wheel multiple times thereafter.

Broke down and bought a new master cylinder that I have yet to install. Wonder if it will make a difference; your post has shattered my confidence.

I will do some testing and see what I come up with for you.. Will post back later.

The only thing I can come up with is that some where you may be getting air in the system or they have been unable to bleed the brakes properly.. I tried to find what I call line blocks but I may not be calling it by its proper name.. What that does "and it takes time" is you go to areas of the braking system unhook the line and put this threaded block on the end to help trouble shoot areas. When you get a firm pedal you know the problem is in that area. I have heard some have a small leak from an O ring from the proportion valve. Its located under drivers side floor board. You should be able no matter how small see a little bit of brake fluid. If this is the case you can replace it or replace the O ring
and bleed the brakes. I have a self bleeding system. But On my last run I still like putting the wife or one of the kids in the van to do the final bleed. Always get the perfect pedal that way. As for other things to look for would be to inspect all lines front and back for leaks and damage some times things from the road damage lines even put a crimp in them, check rubber lines for excessive expansion if you have rear drum check for proper hardware installation and wheel cylinders for leaks. Since they replaced the master cylinder 6 times I would not think thats the issue..One question though. When you replaced the check valve did you mash the brakes with the check valve out to see if the brakes were hard to press.? If not disconnect to see if brakes are hard to push down.. Just curious to see what happens. That could lead me some where else. Van will need to be running for this test.. Also another test pull E brake and see if pedal changes. That will rule out some things..Let me know what you find.. gary

I'm glad to know that im not the only one having these issues. If you have any luck let me know, im going to try what Gary had posted on my thread and see if that works I'll let everyone know.

I know both of you have traction control.. Let me know what type system you have. There could be a pump on this model that may not be pressurizing the system properly.. Im not sure what type of system was used on the Windstar. I do know some systems will apply brakes to some or one of the wheels that slip or loose traction. If that were the case that would make me think your ABS system is not the same as other Windstars. On most Windstar's the ABS should not cause an issue with the regular performance of the brakes unless there is a leak or something. Granted panics stops would suffer and ABS would not be active.But brake pedal would be the same. Do you have a ABS or trac warning light on.?

Also if they pulled the master cylinder I hoped they Bleed the ABS system with a scan tool that allows they ABS pump to run to bleed air out of the pump system..You would have a spongy pedal in this case..

Thanks garync1.

ABS and trac light are both off. I think the trac system does apply brakes, if needed, because one time I put the thing in drive with the front end up on jack stands and the trac light stayed on, solid green. And the ABS pump slammed both calipers silly-hard, non stop, until I turned trac off. It was cool.

Seems like you are on to something with thoughts on ABS bleed and scan tool. 6 master cylinders bad out of the starting gate is possible, but highly unlikely. Midas probably didn't know how to bleed properly.

I guess I may have to break down and visit the stealer ship.