I made a video about this that I'll post at the end of this section. Most times, you can spot a bad caliper simply by looking at the brake pad wear. If the brakes on the left side of your vehicle are worn to the metal and the other side's still got 90% of its friction material left, then you likely have a brake caliper issue. It could also be a brake hose or master cylinder issue, but a brake caliper issue is more likely. It could be either caliper that's bad. Some common issues around this:
- Sometimes calipers won't release; this causes the brake pads to wear prematurely.
- Sometimes the piston freezes in the bore and won't apply the brakes, which leaves a lot of friction material because the brakes are never applied.
- Sometimes it's not the caliper piston that's at fault; sometimes the caliper slide pins stick and cause the problem. I would suggest you check for this first before condemning the caliper.
Remember what I said about using the proper lubricant on caliper slide pins in the above section? The true test is when I try and compress the caliper piston. If I have the bleeder valve open and I can't compress the caliper piston, I replace the caliper. Here's that video I talked about.