Brake pedal goes to the floor after replacing the brake pads

ROBERT GARRISON

MEMBER
2008 MAZDA 5
4 CYL
FWD
AUTOMATIC
187,000 MILES

I changed the brake pads of my friends car, all four. I have changed brakes on many of my car's and others through the years. This one puzzles me. I did not touch nor even open the master cylinder since I did not have to. The first problem that happened was the pedal got mushy so I bled all four RR, RF, FR, FL. After this the mushy went away but now the pedal goes all the way down. Please advice. My only issue is I do not know if she had anybody else touch her brakes after I did it. Puzzling. The only thing I can think of is the master cylinder is bad. If so, how easy is it to replace it. I have never changed one.
Thank you,
Rob

2 Replies

HMAC300

MECHANIC
48,601 POSTS

Have a mechanic use his scanner to bleed the brakes you have air in ABS unit and only way to get it out is to have it bled with a scanner to open all ABS valves.

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Thursday, September 15th, 2016 AT 6:22 AM

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

Hi,

Have you tried bleeding air from the brake system? Here is a link that shows how:

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

If you have tried that and it hasn't helped and there are no leaks, here are the directions for replacing the master cylinder. The attached pics correlate with the directions.

_______________________________________________

2008 Mazda 5 L4-2.3L
Removal and Replacement
Vehicle Brakes and Traction Control Hydraulic System Brake Master Cylinder Service and Repair Removal and Replacement
REMOVAL AND REPLACEMENT
MASTER CYLINDER REMOVAL/INSTALLATION

1. Remove the battery and battery tray.
2. Remove in the order indicated in the table.
3. Install in the reverse order of removal.
4. After installation, add brake fluid, bleed the air, and inspect for fluid leakage.

see pic 1

Reserve Hose (MTX) Removal Note

see pic 2

1. Remove the reserve hose from the reserve tank while pressing the point indicated by the arrow in the figure.

Reserve Hose (MTX) Installation Note
1. Insert the reserve hose to the reserve tank until a click is heard.
2. Verify that the reserve hose is firmly installed by pulling it, and push it into the reserve tank again.

___________________________________________

Here are the bleeding directions specific to your vehicle. Pic 3 correlates with these directions.

2008 Mazda 5 L4-2.3L
Air Bleeding
Vehicle Brakes and Traction Control Hydraulic System Brake Bleeding Service and Repair Procedures Air Bleeding
AIR BLEEDING
AIR BLEEDING

Caution
Brake fluid will damage painted surfaces. Be careful not to spill any on painted surfaces. If it is spilled, wipe it off immediately.

Note
Keep the fluid level in the reserve tank at 3/4 full or more during the air bleeding.
Begin air bleeding with the brake caliper that is furthest from the master cylinder.

Brake fluid type
SAE J1703, FMVSS 116 DOT-3

1. Remove the bleeder cap on the brake caliper, and attach a vinyl tube to the bleeder screw.
2. Place the other end of the vinyl tube in a clear container and fill the container with fluid during air bleeding.
3. Working with two people, one should pump the brake pedal several times and depress and hold the pedal down.

see pic 3

4. While the brake pedal is depressed, the other should loosen the bleeder screw using a commercially available flare nut wrench, drain out any fluid containing air bubbles, and tighten the bleeder screw.

Tightening torque
Front: 7-9 N-m (72-91 kgf-cm, 70-79 in-lbf)
Rear: 12-16 N-m (123-163 kgf-cm, 107-141 in-lbf)

5. Repeat Steps 3 and 4 until no air bubbles are seen.
6. Perform air bleeding as described in the above procedures for all brake calipers.
7. After air bleeding, inspect the following:
Brake operation
Fluid leakage
Fluid level

_______________________________________

Let me know if this helps or if you have other questions.

Take care,
Joe

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