2017 ILX Premium - Spongy Brakes, Time for Brake Fluid Flush?

ClearTheCode admin answer:

A spongy brake pedal on your 2017 Acura ILX Premium with 70,000 miles, especially without a prior brake fluid flush, is a classic symptom of old, moisture-contaminated brake fluid. Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This moisture can lower the fluid's boiling point and lead to corrosion within the brake system.

Causes of Spongy Pedal:

1. Moisture in Fluid: Water in the brake fluid can boil under heavy braking, creating compressible vapor bubbles, leading to a spongy feel.
2. Air in System: Air bubbles are highly compressible and will cause a soft pedal. This can happen if the fluid level gets too low or during component replacement.
3. Worn Components: Less likely if there are no other symptoms, but worn calipers, master cylinder, or brake lines could also contribute.

Brake Fluid Flush Interval: Most manufacturers, including Acura, recommend flushing brake fluid every 2-3 years or 30,000-45,000 miles, regardless of mileage, due to its moisture-absorbing properties. Your vehicle is definitely overdue.

DIY vs. Professional Service: Performing a brake fluid flush is a common DIY maintenance task, but it requires careful attention to detail to avoid introducing air into the system. It's often easier with a second person or a pressure/vacuum bleeder.

Steps for DIY:

1. Fluid Type: Use only DOT3 or DOT4 brake fluid. Acura usually specifies DOT3, but DOT4 is compatible and has a higher boiling point. Ensure it's fresh, sealed fluid.
2. Tools: You'll need a clear hose, a catch bottle, a wrench for bleed screws, and potentially a brake bleeder kit (vacuum or pressure type) or a helper.
3. Bleeding Order: Start with the wheel furthest from the master cylinder and work your way closer: Passenger Rear -> Driver Rear -> Passenger Front -> Driver Front.
4. Procedure (Two-Person Method):
   • Ensure the master cylinder reservoir is full. Keep it topped up throughout the process.
   • Attach the clear hose to the bleed screw of the first caliper and place the other end in a catch bottle with some fresh fluid.
   • Have your helper pump the brake pedal 3-5 times and hold it down firmly.
   • While the pedal is held, open the bleed screw for a few seconds until fluid (and any air bubbles) comes out. Close the screw.
   • Only then release the brake pedal. Never release the pedal while the bleed screw is open.
   • Repeat until clean, bubble-free fluid comes out. Move to the next wheel.
5. Final Check: After bleeding all four wheels, check the pedal feel. It should be firm. Top off the master cylinder reservoir.

When to See a Shop:

• If you're not confident in your ability to bleed the brakes properly.
• If the spongy pedal persists after a thorough flush, which could indicate a more serious issue like a failing master cylinder or ABS modulator.
• If you encounter any difficulty opening bleed screws (they can sometimes seize).

Addressing this issue promptly is important for your safety and the longevity of your brake system.