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Spongy Brakes on 2017 CT6 - Time for a Brake Fluid Flush?

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Mike T. · rep 0 · May 25, 2:54 AM · 1 replies · solved · Question

Vehicle: 2017 Cadillac CT6 Platinum

My 2017 Cadillac CT6 Platinum has about 60,000 miles, and lately, the brake pedal feels a bit spongy. It doesn't feel as firm as it used to, and I have to press it down further to get good stopping power.

I'm wondering if it's time for a brake fluid flush. What's the recommended interval for brake fluid replacement on these cars? Is there a specific DOT fluid type I should use? Also, any tips for bleeding the brakes on a CT6, especially with ABS?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 2:54 AM

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ClearTheCode admin answer:

A spongy brake pedal on your 2017 Cadillac CT6 Platinum, especially at 60,000 miles, is a strong indicator that it's time for a brake fluid flush. Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time, which can significantly degrade its performance.

  1. Why Brake Fluid Degrades: Absorbed water lowers the fluid's boiling point. During heavy braking, the fluid can boil, creating vapor bubbles in the lines. Since vapor is compressible, this leads to a soft, spongy pedal feel and reduced braking effectiveness.
  2. Recommended Interval: Cadillac, like most manufacturers, recommends a brake fluid flush every 2-3 years or 30,000-45,000 miles, whichever comes first. At 60,000 miles, if it hasn't been done, you're definitely overdue.
  3. Fluid Type: Your CT6 requires DOT 4 brake fluid. Ensure you use a high-quality DOT 4 fluid from a reputable brand. Never mix DOT 3 and DOT 4 fluids, although DOT 4 is backward compatible with DOT 3 systems, it's best to stick with the specified type.
  4. Bleeding the Brakes (DIY Considerations): Bleeding brakes on modern vehicles, especially those with ABS and electronic stability control (ESC) like your CT6, can be more complex than older cars. While a two-person manual bleed is possible, a pressure bleeder or vacuum bleeder is highly recommended for consistency and to prevent air from re-entering the system.
    • General Steps: Start with the wheel furthest from the master cylinder (typically rear passenger), then front passenger, rear driver, and finally front driver. Attach a clear hose to the bleeder screw, submerge the other end in a container of new fluid, and open the bleeder. Have a helper slowly press the brake pedal, then close the bleeder before they release the pedal. Repeat until no air bubbles are seen. Crucially, never let the master cylinder reservoir run dry during the process.
    • ABS/ESC: For some vehicles, especially if the master cylinder runs dry or if air enters the ABS module, a scan tool may be required to cycle the ABS pump and bleed the system properly. This is often referred to as an 'ABS service bleed' or 'automated bleed procedure'. Without this, air can remain trapped in the ABS unit.
  5. When to See a Shop: If you're not comfortable with the process, or if you suspect air has entered the ABS module, it's best to have a Cadillac dealership or a trusted independent shop perform the brake fluid flush. They have the necessary diagnostic tools to ensure a complete and effective bleed, especially for the ABS system. Also, if the spongy pedal persists after a proper flush, it could indicate a more serious issue like a failing master cylinder, brake lines, or even a caliper issue, which a professional can diagnose.
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