ARMY TM 9-2805-258-14 AIR FORCE TO 38G2-89-21 NAVY NAVFAC P-8-614-14E 4-56. Compression Test. This task covers: Test INITIAL SET UP Tools General Mechanic’s Tool Kit (Item 1, Appendix B) Wrench, Torque (NSN 5120-0 640-6364) (Item 2, Appendix B) Test.  (figure 4-54) (1) Loosen connector nut (1) and remove high tension cable (2). (2) Remove spark plug (3). (3) Install suitable pressure gage (4). (4) Using starter rope, crank engine over several times and check pressure gage reading. (5) Compression reading should be 90 psi (620 Kpas) at sea level.  The reading will be less above sea level. (6) Remove pressure gage (4). (7) Install spark plug (3). (8) Install high tension cable (2) and tighten connector nut (1). (9) Repeat steps 1 through 8 for remaining cylinder. (10) Compare readings from each cylinder.  The readings should be within 25 psi (173 Kpas) of each other.  Further engine inspection is required if any one reading is inaccurate. 4-114  Change 1