Brake fluid leaking from master cylinder area after replacing front brakes on my 2002 Ford Windstar. I added 12 fl ozs of brake fluid to the reservoir after puttiing in new pads and rotors. Any idea if this might be a loose connection or something? No fluid was leaking prior to the brake job?

There two sections in the master cylinder one half is front the other half is rear, the fluid inside the master cylinder could be bypassing the seals and causing the brakes to fail. Possible master cylinder replacement.

If the fluid is low on the larger section of the master cylinder, it is probably an indication that the front disc brake pads are becoming worn. As the pads wear, the caliper piston moves out of the caliper, requiring more fluid to displace it. Since brake pressure warning and low fluid warning use the same indicator light on the dash, if the brakes are operating normally, its probably not a serious problem. If you had an actual brake system fluid leak, the brakes would not work properly(low pedal, mushy feel, etc.)
You should have the front pads checked, just in case they need to replaced now, rather than just refilling the brake fluid because if you fill it first, then find out the pads need replacement, when the caliper piston is pushed back into its bore, it will push the fluid back into the master cylinder, overflowing the reservoir.
Because brake fluid is hygroscopic, meaning that it attracts moisture from the atmosphere, the water and any associated corrosion/gunk it collects will settle by gravity to the lowest point, the calipers. So, you do not want to push that junk back toward the master cylinder(and thus through the anti-lock brake control), so the proper procedure to be used before pushing the piston in is to, using a brake hose pinch clamp, pinch off the hose, open the caliper bleeder valve, use a small diameter hose to direct the expelled fluid into a waste container. Then after pad replacement, pump the brake pedal to reseat the new pads against the rotors, then refill the master cylinder with appropriate fresh fluid.

Lastly, when there is a cold snap, the brake fluid will contract, many times causing the warning light to come on. Then after driving(due to heat under the hood warming the master cylinder), the light may go off, or you may see the light come on briefly when cornering. This is a normal indication of the aforementioned pad wear. Hope this helps.

A comment from the FixYa Moderation staff:

The brake fluid actually 'contracts', as the ambient temperatures drop. The colder it gets, the more the level is apt to drop, due to this charasteric of brake fluid..

Now, couple this condition with low brake pad thickness, your light will come (the fluid is measured with a sensor in the reservoir) on when it is colder, and go off when the engine compartment warms up; thusly allowing the fluid to expand slightly.

Note that the brake fluid level drops proportionatly to brake pad wear. If you level is low enough to light the light, you are nearing the interval for a brake pad replacement. Adding brake fluid to the master cylinder is NOT advised at this point in time.

If you DO add fluid, and eventually replace the front brake pads, thereafter, the fluid you added will be forced out of the master cylinder, and it will leak all over the paint under the master cylinder. Brake fluid can and will damage painted surfaces.

Best solution we can give you: Simply replace, or have replaced, the front brake pads. The low fluid level condition will rectify itself, as the new pads will force the fluid level in the cylinder reservoir back to its proper level.

Thanks for choosing FixYa

Are you losing any Brake Fluid? Is it visible anywhere at the four wheels? Is it visible anywhere else?
The Master Cylinder may be defective. When you bled the Brakes did you maintain proper Brake Fluid Level in the Master Cylinder? If you didn't: and air entered into the Master Cylinder there maybe air within in the system in the Master Cylinder. You can bleed the Master Cylinder by removing the brake lines, adding more fluid, pumping the brakes, bleeding the air out of the system.
Are you losing Brake Fluid and can't find a noticeable leak? Then there is a good posibility that the rear seal in the Master Cylinder is leaking and the Fluid is going into the Brake Booster - which is the large wheel shaped drum located on the fire wall. In this case both the Brake Booster and the Master Cylinder will have to be removed and replaced. The Booster contains seals that Brake Fluid is very caustic to and will ruin these seals- causing future failures.
If no Brake Fluid is lost, no leak found: Check the Brake Booster Vacuum Advance. This should be connected to the outside of the Booster, attached to a hose, with the hose going to the engine. Check to see if this is working properly. Replace if needed.

1. What is the Brake Fluid Level?
2. Are you losing any Brake fluid at all? Are there any puddles or noticeable wetness on the ground or on the tires/wheels? With vehicle parked, the reservoir filled (overfilled), and engine running: pump the brakes and check on the ground and back sides (inside portions) of the wheels. Look for any brake fluid leaks.
3. Leaks from Calipers usually means a leak from the caliper piston. The rubber seals will be wet.
Leaks from Drums usually means a leak from the wheel cylinder.
4. In any case of leaks from the wheels - replace the calliper OR wheel cylinder.
For caliper leaks: change the brake pads, and clean the rotors with brake cleaner.
For drum leaks: clean the drum and brake hardware with brake cleaner, and replace the shoes.
5. If no leak is detected from the wheel area's: check under the Master Cylinder for wetness indicating a possible leak.
6. If no leak can be found: you MAY have a rear seal leak in the Master Cylinder which is pumping Brake Fluid into the Brake Booster (that large disk looking thing attached to the fire wall, attached to the Master Cylinder in front).
a. Use a large drip/catch pan under the Van in the area on the Master Cylinder.
b. Disconnect the brake lines from the Master Cylinder using a flair wrench.
c. Remove the two nuts (12 or 13mm?) attaching the Master Cylinder to the Brake Booster. If you have been using a lot of fluid, and have found no leaks, here is a good possibilty that all that brake fluid has collected in the Booster; so when you detach the Master Cylinder from the Brake Booster, all that fluid will come rushing out!
7. If there is Brake Fluid inside the Brake Booster: there is no cleaning that out. Brake Fluid is very caustic to the seals inside the Booster and should be replaced.
8. Of course the Master Cylinder will also have to be replaced.
9. After replacing the Master Cylinder/Brake Booster - make sure you get all that spilled brake fluid off the engine compartment area parts! I use a brake cleaner, then mild soap and then water to rinse. Clean any Brake Fluid off Paint imediatley as it will quickly dissolves finishes and paint.
10. If no leak is detected and the Booster is clear, there may be problems with the Booster One-Way Valve. This is attached to the outside of the Booster and has a hose from an "advance" connected to it. This maybe malfunctioning where you are losing power. Replace this first before deciding to replace the whole booster (in cases of NON-LEAKS ONLY). If that did not work, there may be inner seals inside the Booster that have failed. That means a new Booster.
11. In any of the above cases: Make sure you bleed the Master Cylinder correctly and bleed the brakes (at each affected wheel) correctly. Any air in the brake lines will decrease your braking proficiency or could result in brake failure.

Let me know if this helped or if you have any additional information or questions. Feel free to contact me at FixYa.com!

thats odd. Adding brake fluid shouldn't have kicked on the ABS light..

Low brake fluid would cause your RED parking brake light to come on not the orange ABS light (unless thats what you mean. if thats the case its normal for that light to come on with low fluid. in this case check the brake lines starting to the master cylinder and the components at the wheels to make sure there is no leaks if you go HERE complained about your situation and also noticed a leak on the bottom of the master cylinder (hazardous in more than 1 way) )

not sure of the component locations under the hood of the windstar but check to see if you were bumping wires on the ABS control module when you were putting brake fluid in. may be a loose connection that jiggles loose when you drive.

otherwise it might need a new ABS control module or maybe moisture in one of the components.

I just had this trouble. Fuse F-10 will be blown. It is caused by a short in the ABS deactivation switch which is on the front and bottom of the master brake cylinder under the hood. The master brake cylinder is on the drivers side under the hood and is the unit where you add brake fluid. It has a connector with 2 wires on it and when it leaks brake fluid, the 2 wires short out and blow the F10 fuse causing your problem. So check that switch on the bottom front of the master brake cylinder and replace it if you have been losing brake fluid. It fixed my problem.

If you have a bad booster you would have a really hard pedal and it would take two feet to stop. Sounds more like a fluid leak or a bad master cylinder. Are you adding fluid or do you have a red brake light on?

You have a major brake fluid leak. The master cylinder, brake calipers, hose, steel lines or rear wheels cylinders are leaking. Not safe to drive until you repair it.

leaking fluid will not cause a brake to lock up unless the wheel cylinder is leaking and caused the brake shoe to swell. If so, you need a new wheel cylinder.