TM   10-3930-638-24&P 12-12.   COOLING   SYSTEM   TROUBLESHOOTING   (cont) MALFUNCTION TEST  OR  INSPECTION CORRECTIVE  ACTION 1. ENGINE OVERHEATS (cont) Step 6. Check thermostat (para 2-17d). Replace  thermostat  (para  2-17d). 2. ENGINE DOES NOT REACH OPERATING TEMPERATURE Check thermostat (para 2-17d). Replace thermostat (para 2-17d). 3. COOLING SYSTEM NOT PRESSURIZED NOTE With engine at normal operating temperature, run engine at high speed for two minutes and return to idle speed. Carefully cover radiator cap with a cloth and rotate counterclockwise to first detent. A hissing noise from cap and filler neck indicates that system is pressurized. Step 1. Allow engine to cool and remove radiator cap (para 2-17a). Rinse radiator cap with clear water and in- stall on cap adapter and pressure tester as shown. NOTE It may be necessary to reinstall radiator cap several times to ensure tight seal. Operate pressure tester pump and observe meter reading at its highest point. Cap release pressure should be 6 to 9 pounds, and should remain steady for at least 30 seconds. a. If radiator cap pressure is 6 to 9 pounds, and remains steady for at least 30 seconds before dropping, proceed to step 2 below. b. If radiator cap pressure is not 6 to 9 pounds, or if pressure drops rapidly, replace radiator cap Step  2. Disconnect  cap  adapter  from  pressure  tester. Attach pressure tester to radiator filler neck, with locking ears in line with entrance notches of filler neck. Press down on tester and rotate clockwise until locking ears are stopped by stop lugs on radiator filler neck. Clamp radiator inlet and outlet hoses, or block hose flanges. Operate pressure tester pump until meter indicates 9 pounds pressure, and observe meter. 2-26