going down the road the brakes will start to go to the floor

Hi,

If the brake pedal is going to the floor, either you have a leak or the master cylinder is bad. First, here is a link that shows in general how to replace a master cylinder. You can use this as a guide.

https://www.2carpros.com/articles/how-to-replace-a-brake-master-cylinder

Additionally, you will need to bench bleed the new master cylinder prior to installation. Here is a video showing how that is done:

https://youtu.be/WDxvEQrMkBg

If you look at the attachments below, I included the directions and pictures for replacement specific to your vehicle.

I hope this helps. Let me know if you have other questions.

Take care,

Joe

See pics below.