Bust that rust!

Motor, Jun 1999 by Layne, Ken

Hot and Cold Rust

You can't leave the acetylene "wrench" out of your arsenal when dealing with rusted or frozen fasteners. Several of the preceding examples include heating to loosen the nuts and bolts, but many techs reminded us to be careful with the torch. Rubber bushings in steering and suspension parts, as well as fuel lines and hoses, are at the top of the warning list.

Some techs report good luck at welding a nut onto a broken stud or bolt and using wrench force, heat, a good solvent and other tricks to remove the broken part. Others prefer simply to heat it and beat it..with a hammer.

Alternately heating and cooling a broken or frozen stud or bolt is a common practice, but some interesting variations can make this proven technique even more effective. One tech recommended heating the metal surrounding the broken fastener until it glows, then chilling the fastener with a stream of cold water from a spray bottle. Plastic spray bottles with adjustable nozzles are available for a couple bucks at grocery and hardware stores. For best results, fill it with really cold water or keep it in the shop refrigerator.

Another way to heat and chill a rusted fastener works well on problems like a rusty manifold stud. If the stud or bolt protrudes far enough, try heating the surrounding metal to cherry red. The stud also will get hot, of course, so you'll need to chill it to loosen it. Have on hand two or three pairs of vise grips. Clamp one to the stud and watch as it draws the heat out. You actually can see the stud cool instantly. Change the vise grips frequently to keep the heat transferring. The stud will usually shrink down and release.

Just Bust It

If the fastener holds two parts together that can be separated, it's often easiest just to break the bolt. Your faithful impact wrench can do that quickly with its rapid hammer blows, but obviously you don't want to try that on a fastener that must be extracted from a tapped hole. In some cases, you can be your own impact wrench by placing a drift punch against one of the flats on a nut or bolt head. Then strike the drift in a counterclockwise direction with a hammer. This way, you control the force of each hammer blow and don't run the big risk of snapping the bolt or stud.

Besides impact wrenches, hammers and drift punches, other popular tools for stud- and nut-busting include lefthanded drill bits chucked into a reversible drill motor. Not only can you use the bit to drill out a broken fastener, it applies torque in the direction of removal as it cuts the hole.

Ridgid, the plumbing tool company, makes a fastener removal tool set that includes drill guides and fluted cutters. Traditional nut splitters that fit around a rusted nut and use wrench force to clamp a cutting wedge into the nut have been popular for generations. Some techs like to use a die grinder and small cutting wheel as another way to split a rusty nut. For the capscrew broken in a tapped hole, screw extractors come in many sizes and shapes.

If you have a keen eye, a steady hand, a sharp center punch and a sharp set of drills, you can drill down the center of a frozen bolt in successive steps until you're right out to the threads. If the bolt or stud is in a tapped hole, you can then chase out the remaining bits of threads with a tap. If the fastener is a bolt that holds parts together, minor wrench effort will cause the bolt to collapse on itself or shear off to finish the drilling job. (A word of caution: Don't do as the author did years ago and break off a carbide drill bit inside a broken and rusted head bolt so that both the bit and the bolt are sheared at the deck surface. Three weeks later...)