Bleeding Brakes

The fiesta Mk3 brakes come in two variants. Solid or Vented, there is a ABS option, however it is quite rare and not to good! The vented is on most later 3.5 models, SI, RS1800, RS Turbo and XR2i. There are various upgrades about that you can fit from other fords, however fitting bigger brakes doesn''t allways mean you will stop quicker, infact it can make it easier to lock your wheels up! Go back to the basics and make sure your braking system is in good working order before you decide its rubbish and need upgrading.

Brake fluid is often a very overlooked part of the brake system. Here’s what happened. The pads wore so thin that the brake fluid level dropped too low in the master cylinder reservoir. An air bubble or three got pumped into the lines. And because air is compressible, you now have the equivalent of a very soft spring in the solid column of brake fluid between your foot and the wheels. Also over the years moisture can make its way into the braking system, having and effect on boiling point, reducing brake efficiency further (see table below!). Bleeding the brakes will flush that air and moisture out.

The job also involves replacing the old fluid with fresh, which is a good thing. Why would the fluid need to be replaced? It becomes contaminated with atmospheric dirt and abrasive metal wear particles from moving parts in the master cylinder and calipers. It absorbs moisture from the air, which can lower the boiling point of the fluid enough to make it boil at the end of a long downhill grade. (And steam, like air, is compressible.) High temperatures from those high-energy-dissipation stops can degrade the alcohol-based fluid itself. Eventually, your water-clear brake fluid starts to look more like squid ink.

So, your next task is to make sure the bleeder valves can be loosened. You’ll need a spanner that fits the bleeder bolt. A little penetrating oil drizzled on the bolts the day before will help. So will some judicious tapping with a hammer to break up any corrosion. Loosen the bolts, but leave them closed.

If you can’t turn the bleeders without breaking them off, you’ll need to replace the brake calipers or wheel cylinders.

Next you need too use something to suck the fluid out of the reservoir, a pipet is ideal, once done clean out any loose particles and dirt with a rag and top up with new brake fluid.

Get a piece of clear plastic tubing and put one end over the bleed nipple and one end in a clear jar with a inch or two of clean fluid in it. (this stops are being suck back into the caliper)

Now grab your helper.  Here’s the drill: You say “down.” He or she depresses the brake pedal with about the same amount of force needed to keep the car from rolling forward at a traffic light. Then your helper says “down” and keeps the pressure on. When you hear the call, warn your helper that the brake pedal is about to sink underfoot and to keep the pressure on constantly. Then crack the bleeder bolt a quarter-turn.

Some of the old, contaminated fluid will trickle down the tubing into your bottle. When the trickle stops, close the bleed nipple. Then you say “up.” Your helper says “up,” and removes his or her foot from the pedal.

Repeat this process until fresh, clear fluid comes from the bleeder. Any out-of-sequence moves can suck air into the caliper. Yes, the end of the tubing is submerged in fluid, but air can travel past the threads on the bleeder bolt into the caliper if there’s ever any negative pressure in the system while the bleeder is cracked.

Every half-dozen or so iterations, top off the reservoir with fresh fluid. Do not allow the reservoir to get more than half empty — air can be sucked into the master cylinder unless the fluid level remains well above the bottom of the reservoir that feeds the cylinder.

Once clean fluid is coming out, tighten the bled nipple and move onto the next caliper or cylinder. Its best to work fom front to back. Dont forget to keep the reservoir topped up!

Finally, before you drive the car, pump the brake pedal a few times with the car running to build up some pressure!

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