need help on brakes

[jimmm]

Girlfriend has a 2004 Focus.The brakes have failed 3 times, pedal to the floor, no brakes for a few seconds, then they work.I drove it and the brakes worked, but were "funny". Hard pedal, poor brakes, like only the rears were working. Only happens when it's cold and the first few blocks, then everything is normal.And happens maybe once a month or less. Took it to the local garage with certified techs,they ran tests, looked up TSB's, come up empty handed.Didn't charge her but said they didn't want to just replace parts and hoped it was fixed. Once again, it only happens rarely, and only the first couple times you use the brakes,either pedal goes to the floor or 1/2 brakes, then suddenly it's fine.I'm thinking either master cylinder or ABS control.Leaning towards ABS thingy. Retired tech suggested flushing the fluid out which I'll do this weekend,but have doubts it will help. Last guys checked for codes and found none.Any ideas? Thanks!

[MSGDAVE]

It sounds like booster is losing vacumn, or ABS is faulty. You would get a code with ABS though. Look at master cylinder and see ifthere is fluid where it mounts to the booster. Check vacumn lines also.

[APEowner]

This really sounds like master cylinder to me. Here's a fairly reliable test.

If the car is an auto then do this on a level parking lot if it's a stick then you need to find a slight slope. With car car in drive (auto trans) or in neutral facing down a slight grade (manual trans) slowly lift of the brake pedal just enough to let the car roll and then gently apply the brakes until it stops. Repeat several times. If the brake pedal gets closer to the floor every time then the problem is the master cylinder.

[jimmm]

thanks guys. I was thinking if it was the ABS it should throw a code.Being just a now and then problem, I wasn't convinced it was a master cylinder. Looks like this weekend I'll crawl under it and see what I find.

[forddieseldoctor]

If I was going to throw parts at it I would start with the master cylinder. For one it's much cheaper. Second reason is that the brakes are split into 4 separate wheels with the abs. If there was an issue like this being caused by the abs you would very likely only have an issue with one wheel.

[jimmm]

called around, found a shop that seemed to be pretty sharp. Gf took it in, they said a check valve was bad.She picks it up Monday, we will see what happens.