Do I have to bleed brakes after replacing brake master cylinder?

Hello

Yes absolutely you have to bleed them when you install a new master cylinder to remove any air water dirt and old fluid that might be trapped in the lines or you won't get enough system pressure for the brakes to operate properly and as you bleed them you should get your pressure back and your brakes working good again ..good luck hope this helps.. .

Yes, I agree with MECHTRIX, it is a good idea to bleed the brake system. Here is a video to show how to bleed the master before it is installed which is a must.

https://www.youtube.com/watch?v=WDxvEQrMkBg

Please go over this guide and get back to us.