Q: Changed brake master cylinder, bled 10 times, and the pedal is soft The rear brakes are not locked but close. Truck now running rough.

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I changed my brake master cylinder on a newly purchased 1997 4runner due to a soft pedal (no leaks) and bled the brakes 10 times. I bench-bled the master cylinder and had no issues with the install. Saw a video on YouTube that said to run the vehicle to speed and jam on the brakes, thus pushing any air down so it could be bled. Did this in drive and reverse. Brakes made a strange noise when jamming on the brakes in reverse. Now the brakes aren't locked, but not free and the truck is running rough. No issue with the engine idle or rear brakes prior to replacement of MC. Bled the rears and they released. Drove to the store and after backing out they began to draqg in drive and truck is now running rough. HELP!

My car has 225000 miles.
My car has an automatic transmission.

You will have to bleed the brakes from the farthest location all the way to the master cylinder. There is still air in the lines causing the issue. Check the vibrations on the vehicle to see if the engine mounts are damaged or if the brakes are not releasing causing the engine to run harder than normal to overcome the braking force. If you need further assistance with your vehicle’s brake system, then seek out a professional, such as one from Your Mechanic, to help you.

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