E46 330i ZHP Brakes locking on

[Fuel Motorsport]

I changed my brakes and after i changed them i attempted to go for a drive but the front left brake was locked on (don't worry i bled the brakes). I took the tire off, pushed the piston back in, and the rotor spun freely. i tried again and the same thing happened so i thought the caliper was bad. i replaced the caliper and the same thing happened. So, i inspected the line. the line was was cracked and was probably bulging. i replaced the line with a steal braided line leaving the other 3 whatever their factory lines were. now all of the brakes are locked on. i don't want to replace the master cylinder but i cannot think of anything else that would cause this. all of the pads were basically gone so i did push a bunch of fluid back. I don't know if the abs system could cause this or maybe the other 3 not being steal braided could be the issue. but i would like to test the master cylinder before i drop almost $200 on a new one. So any tips on testing or whatever else could be the problem would be appreciated. thank you in advance

[randy72877]

If it is a hydraulic problem like the master, opening the bleeder screw to release the pressure should free up the wheel. If it does not spin free after opening the bleeder then the problem is mechanical (pads, caliper or assembly error) so try this and see what happens. Could even be wrong parts installed.

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[johnjmurray]

I had a similar problem after replacing the front calipers with rebuilt ones. Seems that the rebuilds must have been return items or something. The pistons were stuck. When I tore them open, there was rust and crud all over the pistons. I rebuilt them myself and now they seem fine. You can't always trust that, because a part is new, it's perfect.
Replace the line on a per axle basis. Be prepared with some extra hard line and a flare tool, especially on the rears. Use a pressure bleeder rather than the pedal-pump method, Pumping puts undue travel on the master cylinder piston which could lead to other trouble. Honestly, the bleeder tool is money well spent as you can do the whole job without a helper stomping on the pedal.
To test the ABS, you'll need a computer and the INPA software. I always purge the ABS when I do a full bleed.