Truck Trend Garage: Spongy Pedal Noise on a 2006 F-150 Crew Cab

Alex Steele
Apr 5, 2010
Photographers: Steve Austin
Question: I have a 2006 F-150 Crew Cab with a noisy brake pedal. Every time I depress the pedal, it makes a spongy noise that I believe is inside the boot between the brake pedal and the firewall. I've already sprayed some lubricant into the boot, but that didn't solve anything. Suggestions?
Answer: That rubber boot, where the booster rod connects the brake pedal to the vacuum booster, is part of the booster and also provides a water seal at the firewall. You want to be sure the noise is not coming from something else attached to the brake pedal, other than the booster. Use a screwdriver as a stethoscope to narrow down the source. It could be at the bracket where the pedal pivots or the brake switch, brake pedal positioning mechanism, etc. Once you're sure the noise is coming from the engine compartment side of the boot, make sure the four nuts under the dash that secure the booster are tight, along with the two nuts that hold the master cylinder to the booster, under the hood. Still have the noise? Unbolt the master cylinder, pull it slightly forward, and remove the rod behind it, inside the booster. Grease both ends, reinstall, and recheck for noise. After that, I'd remove the booster and try to reproduce the condition on the workbench, and possibly get a better angle at lubricating the booster/booster rod. Try all that before replacing the entire booster assembly. They're never cheap.
Photo 2/2   |   01z Truck Trend Garage SPONGY PEDAL NOISE

If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.
Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage — visit Alex Steele at

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