Brake problems

[69 Mach 393]

I Finaly got my car running but the brake lines keep getting air in them.All new calipers new master cylinder and booster new brake lines and no visible leaks. It has four wheel disk brakes but the master cylinder is off of a 69 with power brakes. A porportining valve at the back and a residual valve. Where can the air keep coming from. This car looks awsome can someone tell me how to post pictures.

 

[65 fastback]

When you say air is getting in, is the pedal getting softer over time? Maybe there is air in there that you just haven't bleed out yet?

Did you bench bleed the Master Cylinder?

What calipers are you running, front and rear?

The best way to post pictures is to open a free account at PhotoBucket.com. Load your pictures there and link them to here.

Tim

 

[69 Mach 393]

I can bleed them and come back 30 minutes later and have air again. I have to pump them but I can get some brake. The front calipers are stock the back I think were off a 98 Mustang. Yes I did bench bleed the master and even took it off and blead it again tonight.

 

[65 fastback]

I can bleed them and come back 30 minutes later and have air again.

OK, so you definately have a leak somewhere. First, I would put it up on jackstands and take off the wheels. Then try to determine where the air is in the brake line, try to isolate your problem to left/rear, right/rear, left/front or right/front.

Add some clear tubing to each bleeder valve and watch for bubbles in the fluid as you open the valve under pressure.
Once you have determined which section of the brake line is leaking, trace it inch by inch back to the MC. Look for any signs of leakage. Also, check the bleeder valve - it's my guess this could be the problem.

Tim

 

[2nd Mustang]

How are you bleeding the lines?

 

[69 Mach 393]

Just pumping them up and then releasing them.And the air will be in all lines. Master cylinder maby.

 

[2nd Mustang]

Just pumping them up and then releasing them.And the air will be in all lines. Master cylinder maby.

Do a search on bleeding techniques.

Basically when you pump the brake pedal, hold it down, open the bleeder screw and do not let the brake pedal up until you've closed the screw. Letting the brake pedal up while the screw is open will suck air back in if you're not careful.

If you have two people, it's a lot easier. A "one man" bleeding kit also works, but make sure the bottle is higher than the bleeder screw which will help keep air out if doing it with only one person.

 

[NasaGT]

A "one man" bleeding kit also works, but make sure the bottle is higher than the bleeder screw which will help keep air out if doing it with only one person.

Thats good advise, took me awhile to figure out why I had always has a soft pedal using a one-man kit. I was putting the bottle on the ground.

 

[65 fastback]

Did you get your brake issue resolved, yet?

Tim

 

[69 Mach 393]

We are still looking for the brake problem. The air is in all 4 brakes and I do know how to blead the brakes. Has anyone done this conversion and did you use a stock master cylinder. Could the master cylinder be the problem.

 

[Rusty67]

and I do know how to blead the brakes.

That is most likely your problem. Get a friend that knows how to do this to help you and see whats going on. Another option is to buy some speed bleeders from the parts store. Also, go read up on proper brake bleeding techniques.