I replaced the front calipers on my 2005 nissan altima. I bled the lines on the front brakes only. The pedal feels spongey so I bled the brakes again, and still have the same problem.

if this has anti-lock brakes it may be the HCU(hydraulic control unit) may have air in it. it may have to be activated to get all the air out.

Its possible that your rubber lines are collapsed. I've had them keep fluid from going thru as well as not releasing pressure. See if fluid gets to caliper thru rubber. You can plug it with your finger and release pedal. If you feel vacuum and fluid flows well when you push brake, that's probably not the problem. Its somewhere to start tho.

Still air in system, sounds like the master cylinder has ran dry during the bleeding process, pumping more air into system. The lines running to the rear brakes are long, so you must bleed the fluid out the bleed screw in the rear 10+ times each side. Bleed, bleed, and bleed some more, keep bleeding untill that pedal feels good.

Hello Patricia,

Have you checked the master brake cylinder reservoir for brake fluid loss?

I don't suspect the master cylinder as you have replaced it... but am more suspect of a leaking brake line or fitting which should have
been discovered when you had the system bled.

The only time I ever had a rear brake problem with a 2500 series Chevrolet was due to seized rear brake caliper guide pins...as your calipers are also new that is not your problem.

If your brake pedal feels spongy and travels to the floor board you have air in the system, a brake fluid leak or a failure in the power steering system, such as a broken hose, broken power steering pump drive belt, or failed pump, would result in a loss of pressure to both the hydro-boost and steering.

Find more information here:

. Hydro Boost Power Assist Systems Operation Diagnosis and Repair

yes may need to bleed lines at master cylnder

I think you probably did a great job on bleeding the brakes . How about checking the condition of the pads and rotor. Hopefully you replaced them and forgot to mention it in your complaint. Especially if they were full of brake fluid from the bad calipers. Sometimes were so focused on getting to the new procedure we have never done and forget the obvious like correct installiation of the pads and new caliper brake hoses. Sit down have a snack and think over what you missed . I don't think it was in the bleeding.

there is air there somewhere. try manual bleeding the brakes. do the farthest wheel first. if they are calipers all the way around, when you bleed them tap them gently to remove any air that can still be inside the chambers.

robert

You may have a leak in the booster or master cylinder. You can put a pressure tester on the system to test for leaks. It does sound like you have an air leak.
You can try to bleed the master cylinder, then slave cylinder, then brake lines.

possible dirty/defective wheel sensors (typical), or faulty ABS actuator.

Try this a few times.Have someone in the car with it running and you go back to the bleeders and open the furthest one away and have them mash the pedal to the floor,Tighten the screw back up before they let up.Do that to both rear and what ever else lines you have off.By doing this with it running and the bleeder screw open forces any air out of the abs if any.After doing this a few times you should be seeing air and the pedal should come up.Just remember,start car,open bleeder screw and have someone mash it to the floor and hold it,quickly tighten bleeder screw and repeat a few times to what ever lines or calipers you had off.Make sure you keep full of brake fluid.We all tend to forget the simplest stuff when things don't work out right.I hope this works for you and will be here again if you need some more help along with the rest of us.Have a great day and thank you for your time..

I’m happy to assist further over the phone at https://www.6ya.com/expert/joe_a3369546f8067589