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Q: Brake lines have air, bled many times

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My truck constantly gets air in the brake lines. They have been bled multiple times but the issue reoccurs. I had the master cylinder replaced. The system is pressure tested as well. There are no leaks. What might be wrong?

Hello. Moisture in the brake fluid is being boiled off as steam when your brake system temperature gets above 212 degrees (at sea level). The steam re-condenses as water in the system BUT air pockets can be created and remain inside. You might need to bleed the system with new fluid quite a few times to be sure all moisture is removed. Be sure to keep fluid level in the reservoir is at "full" level when done.

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