Picked up a 2008 F250 SD diesel last week. It has been sitting for awhile and the guy drove it with grinding brakes in the rear until the piston pop out of the caliper. He also drove it with no fluid to get it home for a distance going slow. Put new calipers, rotors and pads on the rear but can’t get a good pedal. Have about half, no more air, good fluid coming out of all bleeders and master cylinder. Also activated the abs switch with a scan tool. Any help would be appreciated. Thanks in advance.

 

Most likely the master cylinder is bypassing and needs replacement.Over time a wear ridge forms in the bore of the m/c and with the brake system being in such bad shape resulted in a lower pedal. That exposes the piston seals in the m/c to scrub across that ridge and the seals get damaged. Bench bleed the new m/c, install and rebleed the system using the scan tool should make things good again. If you can get 4-5 power assisted pumps of the brake pedal after a five minute engine shutdown, your brake booster is good.

 

Thanks I was thinking the master might be bad but not sure. Thanks for your time.

 

No problem. Good luck.