ARMY TM 9-2815-259-24 AIR FORCE TO 38G1-125-2 MARINE CORPS 09249A/09246A-24 3-14 TABLE 3-2.  UNIT TROUBLESHOOTING (Sheet 11 of 11) Not OK   OK   OK   Not OK   ENGINE MAKES A HISSING OR   VAPOR LEAKING NOISE Engine makes a hissing or vapor leaking noise. Check for loose or damaged exhaust manifold   (refer to paragraph 3.10.2). Notify next higher level of maintenance. Check for loose fuel injection nozzles (refer to paragraph 3.12.6). Notify next higher level of maintenance. Not OK   OK   Check for evidence of gas leakage around cylinder head gasket. Notify next higher level of maintenance. Notify next higher level of maintenance.