Only One Brakeline Blew-Lost Both Front & Rear Systems

My right rear brakeline blew out on my 2000 Buick Century, but even though the car has dual master cylinder which had been giving me no trouble, brake light not lit, car would stop properly untill blowout, no blowouts or leaks in front brake system, I lost pedal altogether for both systems and had to creep home using emergency brake. Isn’t a dual system supposed to still give me my front brakes, in a rear blowout? ABS seems ok, anti-lock light never came on.

You have been warned. Replace all 4 and bleed the system and you’ll get another 13 years.

Sounds like you may have more than one problem with the brakes on this car…

Agreed with Caddyman and knfenimore.

You got lucky, so if you’re going to keep driving the car, be sure to understand what the 2nd problem is - so you don’t end up without any brakes again.

Thanks for your comments folks. Now all 4 rusty steel brakelines have been replaced with cuni line, the system bled and the brake warning light has went off. But shouldn’t I still had my front system when rear system was lost?

In your opening post, you stated “brake light not lit”.
If you lost ALL your brakes when one brake line recently blew, it makes me wonder if you had previously lost half your brakes, and without your light coming on, you never knew it.

I’ve seen many people loose half a system and keep driving (albeit with a low pedal), and coming in asking why their light is on. They never noticed the lower-than-normal pedal.

If you say your light never came on, could that have been your scenario?

The brake system change that really hurts. Dual systems with shared reservoir. You get to lose all your brakes at the same time. I remember when there was no way to lose all your brakes at once.

The problem with those days was that if the rear brakes didn’t work, you wouldn’t find out until you had to stop in snow or on wet roads. I had two cars do that. I would like to go back to those days with a brake warning light (that works) added.

You system is not split into front and rear, it is dual diagonal. The left front and right rear are 1/2 the system. If your brake fluid is low in the master cylinder, the brake pedal may hit the floor before activating the other side. You then have to let the pedal up all the way and press it down again toget the car stopped. Then call a tow truck.

"If you say your light never came on, could that have been your scenario?"
The brake light always has worked, but it hadn’t come on prior to failure indicating a leak somewhere.
Again, thanks to all for comments and info!

“Dual systems with shared reservoir. You get to lose all your brakes at the same time.”

Every modern master cylinder I’ve seen has a little partition separating the dual fluid inlets, so if one circuit empties the reservoir a small amount of fluid is held for the other side.

I remember the old cast iron reservoirs with 2 separate brake fluid chambers that were each refilled separately. Why aren’t they like that in my car, I’m wondering. It had never happened to me with this type, but I’d say I would have full use of either front or rear system if the other went out.