Brake Pedal Going To Floor After Starting Engine

[hillre55]

Good morning
I have a 2003 Ford Explorer, 4.0, 146,000 miles.
Issue: Brake Pedal Going To Floor After replacement of master cylinder after starting engine. Bench bled master cylinder and bled all four wheels. Before starting engine, I have no spongy brakes at all.

Have any of you experienced this issue after replacing your master cylinder? How did you fix it please?

I didn' even have this brake issue with the master cyliner that was replaced and it had bad seals (was leaking fluid

Could the brake booster be the problem although I didn' have the issue until after replacement of new master cylinder?

Could the new master cylinder be bad? I don' know if it's used or a brand new one?

Thanks
Hope to hear from ANYONE who has experienced this issue.
Have a good weekend

 

[07gtman]

Sounds like there is still air in the master cylinder. if you pump the brakes they are ok ?

 

[hillre55]

Sounds like there is still air in the master cylinder. if you pump the brakes they are ok ?

Yes but not after cranking engine.

 

[hillre55]

Sounds like there is still air in the master cylinder. if you pump the brakes they are ok ?

I will bleed again to see what happens. If this doesn' do the trick, I'm taking master cylinder back for another one. Thanks

 

[07gtman]

bleed it at the master cylinder first and don't let the fluid get to low. also bleed it with the car running and don't push the peddle to the floor.

 

[hillre55]

bleed it at the master cylinder first and don't let the fluid get to low. also bleed it with the car running and don't push the peddle to the floor.

Alright, I finally found a slow leak at left front brake line caliper. I will take fix that and bleed as you stated within next 48 hours. Hate to spend the whole weekend fooling with EX). I really appreciate your time. I'll respond back with update.