Three out of my four disc brakes are dragging. It's gradually getting worse. The car doesn't roll freely and the brakes are hot. A local brake shop mechanic thinks the brake fluid is contaminated with oil or something. He thinks this is causing the rubber seals to expand. I kinda doubt the fluid is contaminated since I've done most of the maintenance, but I guess it's possible somebody added the wrong stuff at some time. The mechanic says the calipers, hoses, and master cylinder have to be replaced and the system flushed. All for $1300, minimum.
I've done a little brake work over the years. Piston seals only cost about $5 per caliper. I think I can replace them. But I'm not sure contamination is the problem. What do you think?
Could water (rust) in the fluid do this?
I once had a brake hose " collapse" on an '86 chevy pickup. The fluid could flow to the caliper but it couldn't return when the pedal was released. This caused the caliper to lock down tight. Could this be the problem?