Can the Master Cylinder handle 50psi? (And brake flush related questions)

[Loco_Hosa]

My truck currently sits with 6 rebuilt wheel cylinders, the lines disconnected.

I assembled a pressure style bleeder using some tools for painting, including a stainless steel pressure pot that I have hooked up to my compressor. I then had a hose made to go from the pressure pot to the MC.

I want to get all of the old nasty fluid out before adding clean brand new fluid, without flushing the debris into the new wheel cylinders. Is there a specific chemical ya'll would recommend, or just flush with air?

Also, when the system is bled, I would like to check the brake system for leaks by pressurizing the MC. My pressure pot and line are both rated up to at least 50psi, but I want to make sure that is not going to be too much for the MC.

Thoughts and input are welcome.

 

[patracy]

50psi is way more than needed. A garden sprayer works fine.

 

[Barrman]

Alcohal is a good flush medium.

as stated, you only need about 5 psi to push stuff through. Sure, you can crank it up to 50 psi, but why spray yourself and the under side of the truck?

 

[Loco_Hosa]

I wasnt sure if Alcohol would be harmful to the rubber components, which is why I asked. Thanks for the rapid reply!

I wasnt clear with the 50psi question. I am going to bleed them at about 5psi, then after I have bled them, I want to seal everything up, crank it up to 50ish, and check to make sure that their are no leaks.

 

[patracy]

5psi will show leaks better than 50 for the reason Barrman pointed out.

 

[Loco_Hosa]

Sure, let me completely restate the question.

After having a wheel cylinder fail me, I am concerned about another brake part failure. I have visually inspected the truck and I see no damaged or worn hoses. Could I father ensure safety by pressure testing the brake system, therefore ensuring that under pressure it will not fail again?

This would be after the brakes are reassembled and bled, I would slowly turn the pressure up to verify that the parts will not fail while applying heavy brake pressure in the future. This would be done before the test drive. Maybe unnecessary, but I would rather have the truck fail in the driveway than going around the block.

My concern, is that the top reservoir of the master cylinder is designed to be vented during normal operation, the pressure being built up in the airpack, lines, and wheel cylinders. Can the reservoir handle the 50psi to test the rest of the system? Or will this harm the MC?

Im sorry I wasnt clear, thank you for the helpful replies.

 

[welldigger]

In a properly functioning brake system 50psi is meaningless. The airpak when fully functional ramps the line pressure upwards of 2000psi. The master cylinder alone can generate several hundred by itself when you push the pedal. Bleed your brakes and stop on the pedal a few times good and hard. That is a way tougher test than pressurizing that an air pot.

 

[welldigger]

Stomp on the pedal *

 

[Loco_Hosa]

In a properly functioning brake system 50psi is meaningless. The airpak when fully functional ramps the line pressure upwards of 2000psi. The master cylinder alone can generate several hundred by itself when you push the pedal. Bleed your brakes and stop on the pedal a few times good and hard. That is a way tougher test than pressurizing that an air pot.

Thats far more than I realized! Thanks for clearing this up for me. I knew 50psi wasnt as much as the line pressure in the brakes, but I didnt realize that the operational preasure was that much. Thanks for explaining.

 

[m-35tom]

you should not be able to hurt anything by pushing on the pedal as hard as you can. that's what you would do in an emergency.