Are they locked from sitting and it is bad enought that the truck will not move?
Or, are they locked after pressing the pedal?
The reason I ask is that rotors will normally rust from moisture and they can get bad enoguh where they can impede the trucks movement and will damage the pads. If the problem is that the caliper is frozen, meaning the pedal has been pressed and the brakes are stuck on, then that is different.
The Master cylinder could be at fault if none of the above is true. Sometimes the seals on the pluger fail and bind the cylinder in place and the pedal will not return. Usually you will see fluid leaking inside the truck near the top of the pivot for the brake pedal. Look for the roid that goes into the mater cylinder and look for fluid around it. If that is the case replace the master cylinder. If not, I am assuming the calipers are rusted so continue with the below instructions.
Either way there will be some possible sacrifices to free up the brakes.
In both cases you will need to get WD-40 or I prefer PB Blaster to break up the rust and corrosion. If the rotors are rusted, spray tehm down and periodically wipe them off and repeat the process. If the caliper is frozen, jack the truck up and remove the wheels. Put jack stands under the frame, soak the piston area and outer edges of the brake pad area, wipe clean periodically and repeat the process.
Either way the pads will probably need to be replaced if enough WD or PB gets on them, but they are not any good after this anyway.
If the caliper is stuck, also soak the mounting hardware so the caliper can be removed later. In both cases really soak the rusted area. After spraying the caliper or rotors and soaking it far a day, get some brake cleaner and spray the brakes down and wipe them off. In the cse of the rotors being the casue, see if it is enough that the rotor can spin free and then replace the pads ASAP. In the case of a frozen caliper, clean off w/brake cleaner and try to remove the mounting bolts for the caliper. If they are hard to turn, spary then with PB again and wait a while longer. Eventually they will break free, you might have to use some force but be careful not to strip off the head of a mounting bolt as caliper hardware is toguht to remove once stripped. Before taking the caliper off, move it back and forth on the rotor to press the piston into the capliper. As you do this, if possible clean the piston with brake cleaner as pushing the piston in will take some of the corrosion into the caliper. Also, spray PB or WD on the pins whcih the caliper moves on. They will be part of the mounting bracket and the caliper can be removed from the brakcet as it "floats" on these 2 pins.
It is hard to say if the calipers will need replacement. The best bet is to get as much of the corrsosion off of the piston before pushing it into the caliper. You will have to do this to make room for new pads. After everything comes aprt, clean and inspect all and grease the pins with high temp grease, make sure the caliper moves freely on the pins. Replace the pads and then get a quart or 2 of brake fluid. The brake system will need to be flushed sompletely. Go to the hardware store and buy some clear hase that fits snugly on the bleed screw, which is another thing to soak in PB and make sure you don't break or strip, and place a 3 or 4 foot length with one end in a bottle to collect fluid and the other on the end of the bleed screw. Have the hose routed over the shock so it is higher than the caliper. Put some axle grease around the threads of the bleed screw. Have someone help you by pumping the brake pedal and holding it. With the pedal held, loosen the bled screw and fluid should start to flow into the tube. Repeat this process and check the master cylinder reserviour frequently and keep it full. If ti empties the system will get air in it and bleeding the sytem will take longer. Once the fluid goes over the highest point in the hose you can have your helper continue pumping and leave the bleeder just loose enough for fluid to flow. Keep the Master Cylinder full and continue until the fluid is clear. Once the problem calipers are done repaeat this for all calipers starting from the passenger rear, then driver rear, then passenger front and lastly driver front. This is flushing the farthest caliper from the master cylinder and workgn towards the closest.
This is the best chance you will have at saving the calipers. Keep an eye for leaks coming from the seals around the pistons.
Hope this helps and be patient with the soak and clean process as it will save time and money to remove rusted Hardware.
Let me knwo how it goes.
Tuesday, November 23rd, 2010 AT 5:32 AM