Brake system fail

Hey guys,

a few days before my father called me per phone and told me about a brake system failure in his '73 vert (all original parts)...

From his words I think it's the master cylinder but I want to know how I can check the whole system with him - we do not see each other often but next weekend I will have a trip to him to visit an Uriah Heep concert and checking his Mustang

His story:

Brake pressure was lost in an hour from full to less and more less till nothing. If he brakes, he felt no pressure and only almost full on the floor he felt a little pressure. The brake light in the tach then is on but only then. He checked some points I told him, the results as he could check it alone: the master cylinder is full of brake fluid, no loss. Also no visible losses on the brake lines and hoses and from the rear brakes. No lost hoses on the power brake booster or the vacuum port on the intake. Brake pedal went through till almost floor then a little bit power but almost nothing.

Any idea? Any check-up list for going through the system?

Thank you very much

I believe you are correct, the master cylinder probably has internal leaks. If it were the booster you would still have pedal, but it would take a lot of force to slow the car. Now would be a good time to go through everything and also rebuild or replace the wheel cylinders and calipers and completely flush all of the lines.

+1 on the master cylinder. Chuck

+1 master, because it is full, and no leaks are detected.

when you see the car try the pedal for yourself to confirm it goes to the floor.

open the cap and look at the level and the color of the fluid.

if the fluid is dark brown and full of junk you will need to think about a total brake hard line replacement.

the hard line rusts from the inside out and releases rust into the fluid. the rust eats the orings from friction over time and you can get a seal failure.

if you just replace the master, and flush the fluid, check the fluid a couple of weeks later if it is dark and brown again those hard lines will need to be replaced.

if the hardlines are rusted then good time to change the rubber soft lines over the rear axle and both front lines.

Tim,

We just went through this exercise. As Don & HCode prescribe, our trouble was with the master cylinder, and that led to new rear wheel cylinders and ordering new rubber lines for all four corners. We rebuilt the front calipers a year ago, and they looked good after flushing, so we didn't tinker any more with them. This thread has me thinking it's time to add new hard lines to the list as well.

Good luck- and enjoy the show and time with your dad!

Butch

quick tip:

if you do your hardlines, DO NOT USE STAINLESS STEEL!!!!!!! stick with regular normal mild steel lines that are galvanized.

i repeat NO STAINLESS ON BRAKE LINES, you will thank me later.

quick tip:

if you do your hardlines, DO NOT USE STAINLESS STEEL!!!!!!! stick with regular normal mild steel lines that are galvanized.

i repeat NO STAINLESS ON BRAKE LINES, you will thank me later.

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+1. Just go with it.

Don, Chuck, Eric, Butch and Dan,

thank you for your numerous replies and your ratings! On saturday I will have a try and check all the things you have mentioned and keep your tips in mind!

I will keep you up to dated, guys! I appreciate your help very much every time!

Good luck- and enjoy the show and time with your dad!Butch

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yeah, thank you ::thumb:: I was waiting for years that my dad and I have the time to go together to a Heep concert. It is the second time we go to such a concert together and the first time we work on his Mustang together - I will enjoy that time very much!