Brake goes to the floor. Doubt it's a fluid leak. Want to figure it out rather than change parts blindly

[BlaineBug]

I believe an internally leaking master cylinder would be suspect if there is no leaking anywhere else in regards to the lines, wheel cylinders, or calipers.  That could be it, it's hard to diagnose without seeing it though.

[diyer2]

28 minutes ago, BlaineBug said:

I believe an internally leaking master cylinder would be suspect if there is no leaking anywhere else in regards to the lines, wheel cylinders, or calipers.  That could be it, it's hard to diagnose without seeing it though.

Agree

[It's Tim]

Water saturated fluid can damage the seals...is the fluid clear?

[Phil Elwood]

Well it's pretty clear in the daylight. Drove up to the truck and saw a big puddle underneath it which was weird because it's way below freezing. Master was empty and when I layed under it this is how the lines looked. Got stainless steel oe replacement line kit by doorman from advanced auto that I'll be throwing in hopefully soon. 

Again thanks to yall for your help, I feel pretty stupid putting "doubt it's a fluid leak" in the title now... Oh well you live and you learn. 

[Black02Silverado]

No worries.  At least you found it and can  fix it.

[Doug_Scott]

A bad master cylinder generally shows up under light braking, for example after your truck has stopped at a red light.  If you lift your foot to the point it is applying just enough force to prevent rolling, you will feel the pedal drop away from your foot.  Pushing hard on the pedal will usually give you a good pedal due to the design of the cup shaped seals. Sometimes you may find a small leak out the rear of the master, that will run down the front face of the booster, but, more times than not, there will not be an obvious leak.  The internal leak generally just ends up back in the reservoir via the compensating port. 

 

Something I noticed over the years is that women drivers noticed a bad master first when spouses shared the car. The husband would bring the car in because the wife complained about the pedal dropping.  Husband brought the car in to show her the brakes were fine. 

[Jsdirt]

3 hours ago, Phil Elwood said:

Well it's pretty clear in the daylight. Drove up to the truck and saw a big puddle underneath it which was weird because it's way below freezing. Master was empty and when I layed under it this is how the lines looked. Got stainless steel oe replacement line kit by doorman from advanced auto that I'll be throwing in hopefully soon. 

Again thanks to yall for your help, I feel pretty stupid putting "doubt it's a fluid leak" in the title now... Oh well you live and you learn. 

...

I had a feeling you'd find something leaking under there. Glad you found it.