General Repair Instructions cont'd

TM 5-2420-224-20-1

NOTE

The following procedure is used with polished and machined steel parts not protected by

cadmium, tin, copper, or other plating or surface treatment. Bare metal surfaces must be

free of moisture when protective coating is applied.

Protective Parts. During repair operations, protect bare steel surfaces from rusting when not

actually undergoing repair work. Dip parts in, or spray them with, corrosion preventive

compound. The same protective coating may be applied to other metals to prevent rust.

Aluminum parts may require protection in atmospheres having a high salt content. Steel parts

must always be protected.

Welding. Welding and brazing may be used to repair cracks in external steel parts, such as

brackets, panels, and light framework. These repairs should be made only when replacement

parts are not available. Do not weld or braze castings, running pads, or parts under great

stress, except in emergencies. When welding is required, refer to TM 9-237.

Stud Installation. When installing studs in engine block and axle housings, use a driver

designed for the stud to be installed. A worn stud driver may damage the end thread. This

makes it necessary to use a chasing die before a nut can be screwed on. This procedure will

remove cadmium plating and allow corrosion, which will make future disassembly difficult and

cause stud to be backed out with nut. Before driving a stud, inspect hole for chips and liquid.

Blow out any foreign matter. Start stud by hand. If it will not start into hole, it is too large or

has defective end thread. Before final insertion, coat thread with antiseize compound; turn stud

in slowly to prevent overheating and galling of casting metal.

Electrical Parts. Replace all broken, worn, or burned electrical wiring. Wires with several broken

strands must be replaced. Broken strands will increase the resistance of the wire and impair

efficiency of electrical components, especially the ignition system. When soldering is required,

refer to TB SIG 222.

Hoses. Replace all broken, frayed, crimped, or soft flexible lines and hoses. Replace stripped

or damaged fittings. Replace entire flexible hose if fittings are damaged. Make sure hose

clamps do not crimp hoses.

Fasteners. Replace any bolt, screw, nut, or fitting with damaged threads. Inspect tapped holes

for thread damage. If cross-threading or galling is evident, retap the holes for the next oversize

screw or stud. When retapping will weaken the part, or when the cost of the part makes

retapping impractical, replace the damaged part. Chasing threads with the proper size tap or

die may often be enough.

10. Dents. Straighten minor body dents by bumping with a soft-faced hammer while using a

wooden block backing.

11. Sheet Metal Repair. Repair minor skin cracks by installing patches.

12. Mounting Holes. Reshape oval mounting holes to round. Drill to receive bushing with required

inner diameter. Stake bushing in place with center punch.

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