83 Ford Fairmont brakes

[Stephen Tashiro]

I need to troubleshoot the brakes on an 83 Ford Fairmont for a friend. A new master cylinder has been installed. When the driver pumps the brakes the pedal goes to the floor with no resistance. With the top of the master cylinder off, I can see a little geyser of fluid shoot up in the reservoir nearest the front of the car when the brakes are pumped. Opened the bleeders on the front disc brakes and felt no fluid or air pressure when the brakes are pumped. I haven't figured out where the bleeders are on the rear drum brakes. The reservoirs of the old master cylinder had what looked like silt in their bottoms. I thought about blowing out the brake lines with air, but I don't know if this is a good idea since (I think) there are some sort of valves on the brake lines downstream of the reservoir. The fluid level in the reservoirs stays high so I don't think any line is broken.

[Jeff Monson]

If a new master cylinder was installed, 1st off bleed the master cylinder, I usually do this off the car. You and a helper can also do it on the car, start by cracking a line loose at the master cylinder and have your helper push down the pedal, (you should get some fluid out of the fitting), then before he lets up on the pedal tighten the fitting. Have him pump the brakes a couple times and repeat the procedure on both the lines coming out of the master cylinder. After that you will have to start at the wheels, I prefer to have someone pump the brakes and crack the bleeder screw while under pressure, tighten the screw and repeat. You are also going to have to bleed the rear brakes, this car has rear drum brakes and the bleeder screw is on the back side of the backing plate. It will look similar to the front bleeder but smaller, they can be a pita if siezed up. Same procedure for the rear, pump up and crack the bleeder, tighten the bleeder and repeat until you get no air and the pedal feels good. It can be time consuming if the system is full of air.

[Joe Pelonio]

It sounds like air in the new master. Did you (he?) bench bleed it? If not you will have to do it and then bleed the entire system again. Actually they were probably not bled before since you couldn't find the rear valves?
Replacing the master requires bleeding the whole system but the master has to be bled before installation. If it was clogged you would not be able
to push the pedal to the floor.

[Matt Meiser]

The bleeders for the rears should be on the back side of the wheel cylinders--about the axle tube.

[Stephen Tashiro]

This car sat unused for 5 years. The brake symptoms before the master cylinder replacement were the same as those after. I wonder if air gradually got into the lines and in between the pistons of the old master cylinder. I'll try the priming and bleeding.

[Pat Germain]

The new master cylinder should have come with some kind of bench bleeding kit. It's typically two, threaded plastic fittings and some plastic tubing. You're supposed to connect the plastic fittings and run the tubing from the fittings back into the fluid reservoir. This allows you to bleed the master cylinder while pumping the fluid back into the reservoir. (Never reuse fluid which has been pumped through the brake system!)

Check for bench bleed kit in the box from the store. You can still use it with the master cylinder installed on the car.

Blowing out the the brake lines with compressed air actually is a good idea. It can help to clear any crud and moisture inside. Then, buy multiple, large bottles of brake fluid. Keep pumping the new fluid through the system until it comes out clear with no air. This will take awhile.

However, since the car has been sitting for awhile, it will likely require new calipers and wheel cylinders. I know; not cheap. But if absolutely anything on a car must work, it's the brakes. Even if the calipers work at first, they are very likely to freeze up on you while out on the road which is a real bummer. :)

[Matt Meiser]

Actually, they should be pretty cheap for that car. It was built on Ford's "Fox" platform along with about every unibody, rear wheel drive car Ford made from the late 70's to the early 90's. Parts are widely interchangeable between them and therefore pretty inexpensive. In fact, you can pretty much transfer the drivetrain and suspension from a Mustang over and make a real sleeper.

[Pat Germain]

Actually, they should be pretty cheap for that car. It was built on Ford's "Fox" platform along with about every unibody, rear wheel drive car Ford made from the late 70's to the early 90's. Parts are widely interchangeable between them and therefore pretty inexpensive. In fact, you can pretty much transfer the drivetrain and suspension from a Mustang over and make a real sleeper.

Good point, Matt. When people are working on a car which essentially has no value (like a 1983 Fairmont), they often balk at buying new components like wheel cylinders, rotors, drums and calipers. But I agree the availability and relative price points are very good.

[Doug W Swanson]

Once you get the master cylinder bled properly, you can bleed the rest of the system.
Be sure to start at the wheel furthest from the master cylinder (typically the right rear, then the left rear, then the right front and then the left front).

Good luck,

[Stephen Tashiro]

The only fittings with new master cylinder (from O'Reilly) were two plastic plugs to screw into the outlets. As to blowing out the brake lines, where would one blow in and where would the air come out? I haven't looked, but aren't there some "proportional" valves between the master cylinder and the bleeder? Would it hurt to blow air through those valves? Would the direction of the blowing matter?

[Jeff Monson]

Take the 2 plastic plugs and screw them into the master cylinder where the lines attach, go in the car and pump the brakes till the pedal is firm, reattach the lines and bleed at the wheels. If you cant get a firm pedal with the 2 plastic plugs installed, then the new master cylinder is bad.

My guess is at the very least you will need rear wheel cylinders, calipers are also a good idea, as Matt stated the parts will be reasonable. Sometimes you are money ahead just replacing them now, working with old rusty bleeders and calipers can be more of a headache than its worth.

[Pat Germain]

The only fittings with new master cylinder (from O'Reilly) were two plastic plugs to screw into the outlets. As to blowing out the brake lines, where would one blow in and where would the air come out? I haven't looked, but aren't there some "proportional" valves between the master cylinder and the bleeder? Would it hurt to blow air through those valves? Would the direction of the blowing matter?

In order to blow out the brake lines, you must disconnect them at each end. Yes, this can be a pain. Of course, once the lines are disconnected, it doesn't matter on which end you attach the air hose.

It's not essential to blow out the line. But do be sure to have a lot of brake fluid on hand to flush those lines thoroughly. You'll be a amazed at the crud that comes out.

[Stephen Tashiro]

Does disconnecting them at each end mean at the master cyclinder and at the wheel ? Or does it mean disconnecting them at the master cyclinder, upstream of the proportional valves, downstream of the proportional valve and at the wheel?

[Pat Germain]

You must disconnect each line from everything so you're blowing air through the line and nothing else.

[Matt Meiser]

IIRC, that proportional valve is basically 2 springs and a piston that balance brake pressure front/back. And it's got the brake light switch (the one in the dash, not the rear brake lights.) But yeah, I wouldn't blow air through it.