Portable Crack Detection
by Jim Richardson

Engines, suspension components, and axles can crack under the stress of normal operation. Anytime you buy used replacements for such items, check them for cracks - preferably before handing over your money - but certainly before installing them on your restoration project.

The Magnaflux Spotcheck Jr. kit comes with two containers of cleaner, plus one container each of penetrant dye, and developer. The tips of the vials are color-coded so you can easily distinguish the vials. A plastic holder is also included, making it convenient to take the kit to swap meets.

Until recently, that was easier said than done, but now there is a kit made by Magnaflux called the Spotcheck Jr. that makes the job easy. Magnaflux, many years ago, came up with the original electromagnetic system that remains the standard, and most thorough, means of detecting cracks. The company name serves as the brand name of the product and the generally accepted term for the process. There are a couple of disadvantages to the old system though.

The biggest drawback to having a part Magnafluxed is that it must be taken to a machine shop because the equipment is not portable. The other limitation of the old method is that it only works on ferrous metals. You can't use it to find cracks in aluminum or brass.

The Spotcheck Jr. kit uses a dye and developer in aerosol vials instead of magnetic flux to find cracks. It not only detects cracks in all metals, it can also detect them in plastic. The kit, including a couple of containers of cleaner, is about the size of a cell phone. You can easily take it with you to swap meets and salvage yards, allowing you to check for hard-to-see cracks before you lay down your cash for parts

.Here's how it's done: First apply cleaner to the part and wipe it with a rag to remove dirt, oil, and grease. The surface must be clean for the test to work. Next, shoot on a little of the red dye, as if you were giving the area a light coat of paint. (The little aerosol canisters are color coded so you can't get confused.) Allow the dye to soak in for a couple of minutes.

Next, shoot a little of the cleaner onto your rag - not onto the part - and then wipe off the dye. (Do not shoot the cleaner directly on the part. If you do, it will cause the red penetrant dye to diffuse and run further into small cracks. This could result in some of the cracks becoming undetectable.) Now shoot on the white powder developer. Even tiny, hairline cracks will become evident almost immediately asbright red lines.

Use a kit like the Spotcheck Jr. to check engine blocks, heads, rods, axles, gears, and frame joints - especially if you can tell the car has been in a collision or it has a lot of miles on it. And if you are overhauling your classic's engine, it would be a good idea to have it checked the old-fashioned way also, because Magnafluxing remains unquestionably the best method for finding cracks in ferrous metals.

Cracks in cast iron or aluminum parts such as blocks, heads, and manifolds can sometimes be welded by professionals, but replacements are always better if they are available, because the high heat required for welding can damage these metals. Cracks in connecting rods and axles should not be repaired. Replacements are the only safe alternative. Frame cracks can usually be welded safely.

	The part to be checked must be clean. Just shoot on the cleaner and wipe with a clean rag.
	Next, shoot on red penetrating dye and allow it a couple of minutes to soak in.
	Wipe the excess dye away by spraying the cleaner onto your cloth, then wiping off the penetrant.
	Finally, shoot on the white developer. If there are any cracks they will show up immediately.