I have a 2003 Chevy suburban. I'm stumped On this issue with the brakes, now when I 1st encountered this I replaced brake lines Just 2 That were busted Then bled the system Just find out master cylinder was bad Replace the master cylinder twice blend system again Still pedal goes to the floor,bled system number of time manually and with the machine still pedal goes to the floor then replaced the 2 rear rubber hoses bled the brakes again,now here's where it gets weird pedal is spongy but it holds for the day then let it sit over night back to the floor just replaced the brake booster still no fix if anyone can help let me know
Welcome to MVM & Repair!
The problem you're experiencing is caused by one of three things:
- Brake pads are missing, brake disks are missing or brakes shoes (inside the brake drums) are not adjusted properly. Make sure the brake pads are in the right place and that there's not a huge hap between the pad's surface and the brake disk. If the rear brakes are drums, make sure the brake shoes are adjusted properly. You can test this very easily by pulling up the hand brake. If you feel no resistance, adjust the shoes, by taking off the drum and turning the self-adjuster.
- There is air in the system. Pretty straight-forward. Bleed the brakes (preferibly starting with the brake that is the furthest from the master cylinder, which will be the rear right on left hand drive vehicles). Loosen the bleed nipple, slowly press the brake, tighten the nipple, release the brake, repeat. Make sure there is sufficient fluid in the resevoir.
- There is a leak in the system or a bleed nipple is not tightened properly. Replace the part that's leaking and bleed the brakes until there's no air in the system.
How to check :
- Check if there is anything missing.
- Check if the adjuster at a good position on your brake booster (the new one usually have a slight difference)
- Bleed the master cylinder.
- Bleed the brake from all tires.
The most overlooked is to bleed the master cylinder because everyone just focuses on the tire.
How to bleed your brakes instruction can be found here:
And don't forget to tighten back your bleed bolt, if the bleed bolt is leaking you will likely get the same result.