One sticking caliper before AND after full brake job.

[KlusterDuck]

My ‘06 S60 T5 has one front caliper that occasionally sticks while driving causing dangerous over-heating. The brakes, flexible brake line, caliper and rotor were replaced but it’s still happening. It’s VERY intermittent, making it hard to diagnose. My mechanic wants to replace the new caliper, but I think it’s something else since the same caliper engages after all parts where replaced. As a side note, I’ve never replaced the brake fluid.

A possibility related symptom is that the pedal is spongy when I start the car after it’s not driven for days. This has occurred for 5 years. The system gets to normal pressure in 10 seconds.)

Thanks in advance.

[br0dy519]

Do you have any fluid loss? It's reasonable that your new caliper is possibly bad. I would remove it and try to work it with a pair of channel locks to make sure it does move. Then depress the brake a few times and make sure it comes back out. Don't go too crazy with it but you should be able to move it with some pliers somewhat easily.

The brakes being spongy after a few days is possibly related to your vacuum pump or the switch for the vacuum pump. Sometimes this is referred to as the brake booster pump. If the car has been sitting overnight, you should hear the pump kick on when your key is in POS2 in the morning prior to starting the car.

[jonesg]

could be dirt in the caliper preventing pressure from releasing.
Could also be in the ABS .

[KlusterDuck]

There is no fluid loss. However, I’ll flush the fluid today, (it’s never been done) and then take it back for a replacement of the new caliper, since the cost is on them. I hope it works because after pricing the ABS hydraulic control module, I have to admit, I got a little weepy….

[chrism]

Brake pedal is spongy when cold and one caliper won’t release. That’s an odd combination. This may be a long shot but I wonder if there’s any chance that there’s something awry inside the master cylinder, like a deteriorated piston seal, that causes both the spongy pedal and then doesn’t allow the fluid pressure to release in the one circuit that feeds that caliper.

[jonesg]

a complete flush would not be out of place considering most parts at the wheel have been changed.
Something is clogging or hanging up in the system.

[June]

You have a bad brake line. Looks won't tell you a thing. So replace the rubber line on both sides. On my 04 S80 the anti-lock valve block had to be activated to get the air out after replacement. June

Mine failed immediately after a brake job by the way.

[br0dy519]

I was going to say collapsed brake hose too. But a fluid flush is necessary either to verify no or low flow. Or a leak.