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Wednesday, June 1, 2022

How to bleed the brakes on a 993 C2 using a Power Bleeder

With the C2, bleeding the brakes is easy because it is unnecessary to actuate the ABS valves to fully bleed the system, as is required on the C4 and Turbo.

I start with 2 liters of fresh brake fluid.
Bleeding the clutch may require a lift to get under the car to the slave bleeder screw. For this reason, I let a local shop bleed the clutch.

A power bleeder with a cap that screws onto the reservoir and a catch bottle used at the bleeder screw on each caliper makes bleeding the brakes a one-man job.

Use a high-quality closed-end box wrench to open and close the bleeder screw ports on the calipers to avoid distorting the screws and damaging them. Use care not to muscle the screw closed. It just needs to be tightened enough to fully seat it and seal the system. The screws should have rubber caps to prevent corrosion. If they are missing, consider getting replacements at any auto parts store. Also, it may be a good idea to paint the threads on the bleeder screws with a bit of clear nail polish when you are done to keep the threads corrosion-free.
  • I use a syringe to draw down the old fluid from the reservoir and top it off with new fluid.
  • I attach the power bleeder and add the remaining fresh fluid to it. In my case, the old and new fluids are the same color, so it is not clear when the old fluid is fully bled out. For this reason, when I bleed the most distant calipers (rears), I waste some of the fresh fluid to ensure the refresh is complete. 
  •  Start with the most distant caliper from the master cylinder. On US-delivered cars: the passenger-side rear caliper, then the other rear caliper, the front right, and finally the front left. Be patient, it may take a while for an adequate amount of fluid to pass through the caliper bleeder screw
    Catch Bottle attached
    to the bleeder screw.
    Into the catch bottle. Also, regularly check the power bleeder's gauge to ensure adequate pressure from the power bleeder, and pump it up as needed.
    I have a homemade catch bottle made from a plastic jar and a short length of fish tank air hose; others buy a commercially made one.
  • On each caliper, I first bleed the inner caliper bleeder port, then the outer. If the system has been opened, I tap the caliper as I bleed it to release any air bubbles that may have clung to the interior of the caliper casting.
  • When bleeding, make sure the power bleeder is under pressure whenever opening a bleeder screw to avoid drawing air in through the screw. Even a small amount of air in the system can make the brake pedal feel spongy.

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