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Brake Pedal Goes to the Floor

63K views 15 replies 6 participants last post by  Timbo 
#1 ·
Hi All- Boy did I screw something up! A little history. About 6 weeks ago my daughter said the brake light on her 2004 Malibu Classic when on. We added fluid and the world was once again fine.

Last weekend she complained of noise while braking. She said it was so bad she didn't want to drive the car so I knew we were in trouble! Sure enough there was no pad left on the passenger inside pad and the inside pad on the driver was very low as well.

So being the good dad, I gave her my car to drive and ordered new rotors, calipers and pads. The passenger side caliper looks like it may have been leaking. Everything went smoothly. Since each caliper was disconnected for a less than a minute I decided to take a short cut and only the bleed the font brakes. Things felt good. When I started the car, the pedal went to the floor so I figured I let in more air than I hoped.

Removing the rear wheels I started bleeding the back passenger brake with my daughter working the brake pedal. I used a plastic tube and bottle so I could watch for bubbles. I did this for both back brakes and did see a few very small bubbles but nothing big. All-in-all we pumped the brakes about 10 times on each of the back brakes.

Again the brakes felt ok until the car was started and brake pedal went right to the floor. Figuring the third time is a charm I started in the back and bled all four brakes like I should have done initially. Each brake got about 10 brake pumps. I didn't see any air bubbles.

Hopeful, I started the car and again the pedal went to the floor.

Do I need to have the engine running when I bleed the brakes? I've never had to do this before, although this the first time I'm working on a Malibu. Any other thoughts?

Thanks,
 
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#2 ·
Do I need to have the engine running when I bleed the brakes?

Any other thoughts?
I would say yes, on any vehicle with power assisited brakes.
Be sure to keep the master cylinder full AND don't press the pedal too hard or fast.

NOW.......in the future, remember that there are TWO ways you can tell that your pads are worn out: 1) screeching noises from brakes and 2) level of fluid is low in the master cylinder reservoir.

You should NEVER just add fluid; you should find out WHY it is LOW. ;)
 
#3 ·
OK. I will try with the engine running. I've never run the engine while bleeding brakes on any of my cars before but at this point I'm so frustrated if you told me to replace the antifreeze I would probably try that too!

This car was handed down to my second daughter from the first daughter, I just figured the brake fluid was never, ever checked. I looked at the brake lines to see if they were weepy, but everthing was amazingly clean and rust free. I figured if there was a leak we would be adding more fluid but it never went down. In retrospect, your advice makes alot of sense. The fluid had to go some place. I should have hunted.

As for screeching noise...tell me about it! I would think with metal against metal the car would have been pulling long before she started complaining of about "a rubbing noise."
 
#6 ·
The fluid had to go some place. I should have hunted.
Just to be sure we are straight here......normal wear of the pads makes the fluid level go down.

If you are ONLY going to replace the pads, you do NOT want to top off the fluid because when you push the calipers back to fit the new pads, the fluid level rises again and often overflows. Makes a mess.
 
#4 ·
You might have air in the ABS system. If that's the case, the best way to clear it is have some shop run an automated bleed procedure. Below is how to do the automated bleed procedure but you need a scan tool with bi-directional control.

Antilock Brake System Automated Bleed
Bleeding the ABS System
Caution: Refer to Brake Fluid Irritant Caution in the Preface section.

Notice: Refer to Brake Fluid Effects on Paint and Electrical Components Notice in the Preface section.

Perform a manual or pressure bleeding procedure. Refer to Hydraulic Brake System Bleeding . If the desired brake pedal height results are not achieved, perform the automated bleed procedure below.

The procedure cycles the system valves and runs the pump in order to purge the air from the secondary circuits normally closed off during normal base brake operation and bleeding. The automated bleed procedure is recommended when air ingestion is suspected in the secondary circuits, or when the BPMV has been replaced.

Automated Bleed Procedure
Notice: The Auto Bleed Procedure may be terminated at any time during the process by pressing the EXIT button. No further Scan Tool prompts pertaining to the Auto Bleed procedure will be given. After exiting the bleed procedure, relieve bleed pressure and disconnect bleed equipment per manufacturers instructions. Failure to properly relieve pressure may result in spilled brake fluid causing damage to components and painted surfaces.

Raise the vehicle on a suitable support. Refer to Lifting and Jacking the Vehicle .
Remove all four tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation .
Inspect the brake system for leaks and visual damage. Refer to Brake Fluid Loss or Symptoms - Hydraulic Brakes . Repair or replace as needed.
Inspect the battery state of charge. Refer to Battery Inspection/Test .
Install a scan tool.
Turn ON the ignition, with the engine OFF.
With the scan tool, establish communications with the EBCM. Select Special Functions. Select Automated Bleed from the Special Functions menu.
Bleed the base brake system. Refer to Hydraulic Brake System Bleeding .
Follow the scan tool directions until the desired brake pedal height is achieved.
If the bleed procedure is aborted, a malfunction exists. Perform the following steps before resuming the bleed procedure:
• If a DTC is detected, refer to Diagnostic Trouble Code (DTC) List - Vehicle , to diagnose the appropriate DTC.

• If the brake pedal feels spongy, perform the conventional brake bleed procedure again. Refer to Hydraulic Brake System Bleeding .

When the desired pedal height is achieved, press the brake pedal in order to inspect for firmness.
Remove the scan tool.
Install the tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation .
Inspect the brake fluid level. Refer to Master Cylinder Reservoir Filling .
Road test the vehicle while inspecting that the pedal remains high and firm.
 
#5 ·
Based on what I see in the pressurized bleed procedure, if the ABS has not been activated then the secondary circuits are closed off. During the manual bleed procedure that the OP performed how likely is it that any air could have gotten into the ABS circuits? I hope none but I don't know so I'm asking.

OP,
How many miles on the car? If there are a lot of miles, like over 200K, then it might be a good time to consider replacing the soft brake hoses. One at each corner I would imagine but an inspection or a call to your local parts store would confirm how many.

When you were bleeding, was there any point when your daughter lifted her foot and the master cylinder sucked in more air? Did you keep the reservoir filled? When lifting her foot did she do it slowly? When pumping, did she hold her foot firmly all the way down? Did she wait to pump until after you shut the bleed screw? I'm sure you did it right but examining your actions might reveal a small issue that results in a simple solution.
 
#7 ·
When you were bleeding, was there any point when your daughter lifted her foot and the master cylinder sucked in more air? Did you keep the reservoir filled? When lifting her foot did she do it slowly? When pumping, did she hold her foot firmly all the way down? Did she wait to pump until after you shut the bleed screw? I'm sure you did it right but examining your actions might reveal a small issue that results in a simple solution.
I can't speak to what my daughter actually did or didn't do, but I've convinced myself that what I tell you was done may not be what actually took place! At the end of the day - I think I have lots of air in my system.

Even when doing a two person bleed I use a hose and bottle. I angle the tube up so it always has fluid at the bleeder. This way if she lets up before I ask, 1.) I can tell; 2.) we suck fluid in, not air.

I work from home so today at lunch I'm moving my office to the garage (have cell phone and laptop - can work!) and gravity bleed the fronts for a long time.

I'm working on borrowing a brakescan tool.

I've had soggy brakes when I have thought I was finished, but never no brakes. Thanks everyone for your advice and help.

George
 
#8 ·
The ABS sytem is very prone to trapping air even with the system at rest so if fluid level got too low and air was ingested, it's almost a guarantee it's trapped in the ABS hydraulic unit. You can gravity bleed 'til you're blue in the face until you do the automated bleed, you'll have air in the system.
 
#9 ·
You can gravity bleed 'til you're blue in the face until you do the automated bleed, you'll have air in the system.
Fortunately or unfortunately I never got the time to do the gravity bleed. Air in the ABS is sounding better and better. With no brakes at all, it's hard to take the car somewhere to have them do this.
 
#10 ·
Sorry, not much I can say there. You can try more manual bleeding to see what happens, maybe you can get it driveable to get it to a shop that can do the automated bleed. I wouldn't pump the brakes, just down and hold the pedal, open the bleeder, get out what ever comes out, tighten the bleeder and release the pedal, wait 10 seconds and repeat that a few times at each corner. Pumping the pedal too much can distribute the air in the fluid making it harder to get it all out.
 
#11 ·
The only thing I can suggest on the ABS, and I have no idea if it'll work on the system on the Malibu, is what's done by folks using the Teves Mk IV on the later MN12 Tbirds/Cougars/FN10 Mark VIIIs.

Bring it up to about 60 MP where you've got a nice long run, no traffic, and ... stomp the brakes to induce ABS.

Lather, rinse, repeat, checking brake fluid every other time.

That works on the Teves Mk IV system, have NO idea if it works on the Malibu's system.

(For those wanting theory - when you do that, the pump pressurizes the system, and drives the air bubbles towards the wheel cylinders, where a gravity bleed or normal bleed can get them out. Or even a pressure bleed, the preferred way to bleed on that system.)

RwP
 
#12 ·
Bring it up to about 60 MP where you've got a nice long run, no traffic, and ... stomp the brakes to induce ABS.
Nothing personal but this is the funniest thing I've read all day! Granted I'm bummed about the problem, but I don't have a death wish. This car has no braking so I'm not about to drive at 60 MPH!

I do like the creativity of the solution though. Where are those nice icy roads when you need them? If this was January I could do it in my driveway!

Thanks for the help.
 
#14 ·
Hi Everyone - I have brakes! You can laugh with me or laugh at me, the latter is more appropriate when you hear what I did. First, I can't believe I made this mistake and second I can't believe I didn't catch this mistake - I know better!

It is with much embarrassment that I admit I put the calipers on the wrong sides! The right was on the left and left was on the right. I can blame it on the Autozone guy who marked the boxes incorrectly, but I know the bleeder has to be higher than brake line! In fact I took a picture of the caliper before I removed it and it shows the bleeder on top. You can also see it in my Haynes manual. It's not like I never did brakes before. I grabbed the marked box and didn't engage my brain when installing.

Oh well. Trashed are my dreams of gving up my day job! Just kidding. I make enough money that I don't need to be under a car...but it's fun, besides it's one of few places I can go that my wife doesn't follow!

Thanks eveyone for your opinions. I did learn about ABS problems.

"Stupid is as stupid does." - Forrest Gump

:D
 
#16 ·
Thanks for posting your solution as I just did the same thing. It was late last night, trying to get it done and I pulled the old off and new on. This morning between rain storms I Tried to bleed the system and the pedal still fell to the floor. I searched the web and Youtube and people all pointed to a bad booster pump. I found this and was about to give up until I read your finally post and thought "Gee Did I do that too?" Yep I did. Brakes are good...Thanks again...if I wasn't already bald I would have been! LOL
 
#15 ·
It shows the measure of a man when he can admit his faults, learn from them and grow, and help others to do the same.

Good job!

And thanks for sharing the info. It'll possibly keep one or more of us from having the same episode some day.
 
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