ARMY TM 9-2815-260-24 AIR FORCE TO 38G1-126-2 MARINE CORPS TM 09244A/09245A-24 3-13 TABLE 3-2.  UNIT TROUBLESHOOTING (Sheet 10 of 11) ENGINE KNOCKS Engine knocks. Check for dirty, defective, or leaking fuel injection nozzles (refer to paragraph 3.12.6). Perform end item troubleshooting procedures (refer to TM 9-6115-672-14 or other applicable TM). Notify next higher level of maintenance. Not  OK OK Not OK   OK   OK   Not OK   Abnormal engine noise. Check for worn or damaged water pump bearing (refer to paragraph 3.8.3). Replace water pump (refer to paragraph 3.8.3). Check for damaged battery charging alternator (refer to paragraph 3.9.1). Repair or replace battery charging alternator (refer to paragraph 3.9.1). Perform end item troubleshooting procedures (refer to TM 9-6115-672-14 or other applicable TM). Notify next higher level of maintenance. ABNORMAL ENGINE NOISE Notify next higher level of maintenance.