E46 Sticking front brake calipers

Greetings all,
I have an '01 330I that has been plagued with sticking front brake calipers since I bought it four and a half years ago. I have replaced both with remanufactured calipers, replaced the ends of the brake lines, and installed new rotors (slotted) and pads (Cool Carbon). One side inevitably sticks with the lightest application of the brakes, and takes several hours to release. Suggestions? Non-remanufactured parts? Master cylinder? Exorcist?
Many thanks, Rich

Sent from my XT907 using Bimmer App

For a long-running problem like this and having changed the calipers I would be looking at the master cylinder. Sometimes they don't fully release pressure when the brake pedal is released. The symptoms get worse and worse the more the car is run as the brakes and brake fluid gets heated up.
To test this you can go for a run and when you get back loosen the bleed nipple on a front wheel, briefly. If the brake fluid spurts out, rather than just falls out, fasten it back up and go for another run getting the brakes fully hot again. Then undo a bleed nipple on a rear wheel. If the brake fluid spurts out of that too it is likely to be the master cylinder.

GolfingDuck,
Many thanks for your reply! I've been reading many threads on this site to get some ideas, and I'm also inclined to believe the master cylinder is malfunctioning. I can rule out warping because it rolls smoothly once the caliper releases, and I've isolated the problem as being on one side by comparing the relative amount of heat coming off of the rotors after I've driven. I can also feel the wheel binding and hear it resist turning when I start very gradually (no gas, gradual clutch release). The good news is that it goes to my regular mechanic in the morning, so this will give me an area of conversation to begin with.
I'll post my results when it comes back from the shop.
Rich:

GolfingDuck,
Many thanks for your reply! I've been reading many threads on this site to get some ideas, and I'm also inclined to believe the master cylinder is malfunctioning. I can rule out warping because it rolls smoothly once the caliper releases, and I've isolated the problem as being on one side by comparing the relative amount of heat coming off of the rotors after I've driven. I can also feel the wheel binding and hear it resist turning when I start very gradually (no gas, gradual clutch release). The good news is that it goes to my regular mechanic in the morning, so this will give me an area of conversation to begin with.
I'll post my results when it comes back from the shop.
Rich

ABS unit?

Hummer,
I did not think of that! I have sent the car to my mechanic; I will ask him to check.
Many thanks,
Rich

Start with a proper bleeding, it's the cheapest place to start.
If you have air in the hydraulics the system won't work as efficient, or properly.

update? I have the same problem. Replaced calipers, pads, lines, and rotors and it actually got worse.

NASA e30,
It's at my mechanic's right now, and he is ordering a new caliper...Not sure if this will fix it, but I sure hope so. I'll keep the forum posted.

Cool. Ill add one more data point that I forgot to mention, my old calipers had the brass bushing for the slide pins. They kept seizing up, so I thought that was my problem. Not so sure anymore.

^
I would say it shouldn't be your brass bushings - unless there's major rust on the pins. Also, you must use the supplied guide pins that came with the brass bushings! (if you use stock pins it may cause the binding issues described.

OP,
Here's my suggestion:
(assuming fresh brake fluids and proper bleeding along with those re-manufactured calipers... )

If you're still experiencing random brake binding, I'd suspect the hub bearings has failed on that particular side.

Remove the brake caliper completely (leaving the rotor on the hub) and give it a spin, see if it is spinning smoothly without
'odd' noises. If you need reference to what a failed hub/bearing sounds like, search my vids on my channel below.

Let us know what you find out.

to E46Fanatics
My thanks to all my fellow fanatics for your experience and advice. My mechanic diagnosed a bad caliper, replaced it, and is returning it to his supplier without charging me for the part! I'll keep you all updated if the situation changes.
Rich