ChaosPhoenixFix

I know I've been MIA for a while, but hoping you all can help. I am not that good with brakes either. I have a 79 with my brake idiot light on on the dash. Brakes peddle went soft when it happened. I cannot find any leaks. When I remove cover from the master cylinder and pump the brakes I get fluid pushing up from the front hole, but nothing from the back hole. Is this normal? Could it be air in the lines and they just need to be bled?

Any and all help would be awesome as I PCS in a month, and I would rather drive her there than trailer her.

righthanddrive

I would look into your proportioning valve, check all of your wheel cylinders again,and check your e-brake switch causing the light to come on.
Your master cylinder could be bad also.

There are ways of trying to reset your proportioning valve before buying a new one also.

You may be able to remove the wire to each of the switches to determine which one is causing the light to come also.

Definitely get the brakes working .

As I remember the back side of the master cylinder kicks in when the front ( primary ) well fails.

Good luck.

Peterbuilt

Since you say that no calipers are leaking you might want to start by checking the master cylinder.
One way is to apply and hold pressure to the MC and see if the pedal slowly goes down.

Another way is to remove the front brake line at the MC and plug the MC port.
Then reattach the front line and plug the rear port, if the pedal is NOT rock hard for both tests then the MC is bad.

DUB

Assuming that you looked at where the master cylinder attaches to your power brake booster..and you do not see brake fluid running down the underside of that area....then ...honestly. Sometimes I will remove the nuts that hold the master cylinder and look at the backside of the master cylinder and make sure I SEE NO BRAKE FLUID. The I re-install it. I would bleed the brake if you are 100% certain that you do not see any brake fluid from any of the four calipers.

IF you get the warning light to go out and have good brakes. Write down your mileage and the date. So...if it happens again...you can see how many miles it took to come back....because THAT amount of mileage can better direct you to how big or small of a problem you are looking for is.

DUB

drwet

Pretty sure your master cylinder has failed.

Sluefoot

Ah.....these cars do NOT have "wheel cylinders"...

I would do the checks recommended for checking the m/c, THEN go ahead & bleed the rear brakes....REMEMBER, there is an INSIDE bleeder that you bleed FIRST, then the OUTSIDE bleeder! Do the right rear first, then the left rear.

Depending on how long it's been, I'd let the lines gravity feed long enough to clear out all the old fluid....especially if it's dark colored!