* Caliper Piston Seizing: This is a very common cause. The caliper piston, which pushes the brake pads against the rotor, can seize due to corrosion, rust, or a build-up of debris. This prevents the piston from retracting fully, keeping the pads pressed against the rotor.
* Caliper Slide Pins (or Pins and Boots): These pins allow the caliper to slide freely along the caliper bracket. If they're seized due to corrosion or damage to the rubber boots protecting them, the caliper can't move freely, leading to constant contact with the rotor.
* Brake Pad Issues: While less likely to *cause* sticking on their own, severely worn or damaged brake pads can sometimes contribute to sticking. For example, a pad that's significantly thicker on one side than the other might cause uneven pressure and sticking. Also, a pad that's seized in its caliper can contribute to the problem.
* Brake Lines: A restricted or kinked brake line can prevent proper pressure release, leading to the brakes dragging.
* Master Cylinder: A malfunctioning master cylinder could cause excessive brake pressure, even when the brake pedal isn't depressed. This is less common but possible.
* Vacuum Booster: A failing vacuum booster can also cause problems. It assists the master cylinder in creating brake pressure. A leak or failure can lead to increased pressure.
* Parking Brake Cable: A seized or improperly adjusted parking brake cable can cause the front brakes to drag. (Though more likely to affect the rear brakes)
* Wheel Bearing Problems: In very rare cases, a severely damaged wheel bearing could lead to friction that *feels* like the brakes are dragging, though this typically involves other symptoms like noises or play in the wheel.
To diagnose the problem:
A visual inspection is a good starting point. Check the calipers for signs of corrosion or binding. Try to move the caliper pistons by hand (carefully!). Examine the slide pins and their boots. Check the brake pads for wear and tear. If you're not comfortable doing this yourself, take your van to a qualified mechanic for a proper diagnosis and repair. They have the tools and expertise to pinpoint the exact cause and fix it safely and effectively.
