80 Malibu Brake Issues - Help

[Anonymous]

Ok, here's the deal. Previously the brake pedal on my Malibu was going directly to the floor and it would not stop. The "Brake" light was constantly lit on the dash. So I replaced all 4 brakes (they looked shot anyay). New discs, calipers and pads in the fronts, and new drums and shoes in the rears. The rear Pass side also got a new wheel cylinder. The driver's side wheel cylinder seems OK and isn't leaking or anything. I also replaced the master cylinder for good measure. Then I bleed down all 4 wheels and HAD a very solid pedal feel. But I've still got a weird problem.

Here's what's happening now. I went to test drive the car last night. When I first sat in the car it still had a solid pedal. As soon as I started the car the pedal went right to the floor and still does. What gives with that? I didn't notice any leaks, and the resevoir was still full after the test drive.

Any thoughts on what the heck is going on??? I need to get this fixed ASAP!!!

 

[DatBu]

Oh man, this same thing just happened to me. I thought it was a vacuum issue , but it checked out fine. I ended up finding a small leak in my line right behind the back seat area. If you have somewhat rusty lines, id suggest checking them out all the way back. Sometimes the frame catches the leak and it's very hard to notice.

 

[LS6 Tommy]

Did you bench bleed the new master cylinder before installing it?

Tommy

 

[wiseman79]

x2 on looking for a leak.

 

[malibuplotter]

wow that sounds pretty scary.. please report back and let us know what you found out. my guess was brake booster but i'm second guessing myself now.

 

[Doober]

X2 on the leak. My leak was as the line just started to curve up to follow the frame in front of the axle, about even with the rear seat I believe.

 

[Anonymous]

Yes the MC was bench bled.

I was told to try and gravity bleed the system, which I have not had time to do in the last 2 days or so. I'm hoping that might be the issue, that there is still some air (and probably still some old crappy watered down brake fluid) left in the lines. A complete flushdown until new fluid squirts out the bleeders is definitely in order.

Up until I started to do this work the car sat in my driveway for a good year, and before that there were brake issues, so it's anyone's guess at this point.

 

[Anonymous]

So the gravity bleeding didn't fix it. It did give a decent pedal feel until I started the car, at which case the pedal went right back to the floor.

I'm thinking the power booster is shot. It is 27 years old and has sat for a while.

There doesn't APPEAR to be any other leaks in the lines at this point, and since I do get a decent pedal while the car is turned off I think the lines are OK. I'm just running out of parts to replace.

 

[LS6 Tommy]

So the gravity bleeding didn't fix it. It did give a decent pedal feel until I started the car, at which case the pedal went right back to the floor.

I'm thinking the power booster is shot. It is 27 years old and has sat for a while.

There doesn't APPEAR to be any other leaks in the lines at this point, and since I do get a decent pedal while the car is turned off I think the lines are OK. I'm just running out of parts to replace.

It's not the booster. Your pedal effort would be sky high if it was bad. Sounds more and more like a bypassing master to me.

Tommy

 

[Anonymous]

Well it's all fixed. I said screw it and ended up replacing the power booster, master cylinder and all the brakes lines. Now everything is brand new and working great.

Sometimes you have to bite the bullet, suck it up and replace it all.