Help! Brake question

Off topic car, but on topic question. This is my daily driver. Rear drum, front disk, power boosted.

Pulling in my driveway yesterday, the pedal drops to the floor, no brakes, and I shoot across the yard. There is no loss of fluid, so I assume the master cylinder is dead.

I go to the friendly local AutoZone today and buy a master cylinder. I put the master cylinder on tonight, again pedal goes straight to the floor. Again no loss of fluid.

What am I missing? I didn't bench bleed the master cylinder, but I expected spongy. This has no pedal resistance at all. Any ideas?

 

Have you checked for broken lines/hoses??

 

I thought of that too, but I don't seem to be losing any brake fluid.

 

You need to bleed the master cylinder first(always) it primes the cylinder and then you bleed the lines at the master and your done. But in your case you skip the first step, so now bench bleed it on car(take the lines off and bleed the master,then bleed the farthest rear wheel(passenger rear) first then other rear wheel then right front and last left front.Also if you get no pedal and brake light is on,let off pedal open front caliper bleeder and push pedal down till light goes out and proportion valve trips back.Then you should have brakes,good luck.

 

Pedal still connected to the push rod? Everything look normal under the dash?

Even if you didn't bench bleed the m/c, you should still get something as you pump it.

 

bench bleed the m/c

really

 

Bench bleed the cyl. Make sure the new cyl. is the correct one (push rod length). And be sure the new one isn't leaking out the back and into the booster. Make sure the vacuum valve is working properly. Make sure there are no leaks from the wheel cylinders.

 

Becnh Bleed The New Master Cylinder And Youll Have To Bleed All 4 Wheels Untill Strait Fluid Comes Out,may Take A Bit To Get Rid Of All The Air--good Luck