The valve covers on your car's engine protect the valves inside. These covers are typically held in place with a series of bolts to allow for easy removal of the valve cover for replacement and servicing. Occasionally, these bolts can shear off, rendering the valve cover stuck. If this happens, there are a number of techniques you can try to remove a broken bolt from a valve cover.
Clean off the area around the broken bolt on the valve cover with engine degreaser and a rag. This will give you a better grip on the problem bolt.
Spray penetrating lubricant onto the bolt. Allow this time to soak in according to the manufacturer's instructions. The longer you let it soak in, the better.
Clamp a pair of vise grip pliers onto the broken end of the bolt. Tighten the clamps so the pliers are secure. Turn the bolt with the pliers counterclockwise to back it out of the hole.
File down the broken part of the bolt until it is flush with the valve cover. Attach a bit that is small enough to fit inside the bolt body to a power drill and drill a small pilot hole in the center of the bolt. Insert a bolt extractor into the end of the bolt and back the bolt out by turning the extractor with a wrench.
Heat the bolt and surrounding area with a propane torch. This step should only be employed if the engine has been removed from the vehicle as the propane could ignite exhaust and gasoline fumes. Work in a well-ventilated area and heat the bolt until it glows a dull red color. Remove the bolt with the vise grips.
