ARMY TM 9-2815-260-24 AIR FORCE TO 38G1-126-2 MARINE CORPS TM 09244A/09245A-24 3-20 c.   Replacement. NOTE Replace thermostat if suspected of being defective. (1) Remove thermostat and water manifold/thermostat cover, refer to step a. (2) Inspect thermostat and water manifold/thermostat cover, refer to step b.  Replace parts found defective. (3) Position new O-ring seal (12, Figure 3-1) on water manifold / thermostat cover and install plug (11). (4) Install thermostat (9), refer to step d. d.   Installation. (1) Remove all covering installed during step a (6). (2) Ensure all old gasket material is removed from gasket surfaces. (3) Lubricate seal (5) with multi-purpose grease. Install seal. (4) Install guide studs (1, Figure 3-2) if needed, in place of capscrews (6 and 7, Figure 3-1) and position gasket (10, Figure 3-1) on cylinder head. (5) Connect water temperature sending unit (15). (6) Position thermostat (9, Figure 3-1) and water manifold / thermostat cover (8) on cylinder head using a screwdriver (2, Figure 3-2) to hold thermostat in place, refer to Figure 3-2. NOTE Remove one guide stud, if used, and install one capscrew before removing second guide stud. (7) Remove guide studs, if used, and install capscrews (6 and 7, Figure 3-1).  Torque capscrews evenly to 52 lb-ft (70 Nm). (8) Install water pump tube (4). (9) Position clamps (3) on cylinder head and alternator bracket and install capscrews (1 and 2). (10) Connect coolant outlet hose, refer to TM 9-6115-672-14. NOTE Air must be expelled from system when refilled with coolant.  Loosen plug in thermostat housing to allow air to escape when filling system.  Retighten plug when all air has been expelled. (11) Service coolant system, refer to TM 9-6115-672-14.