TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
Page 482 of 779
(4) Preclean core interior to remove oil and loose sludge from the core to reduce con- tamination of cleaning solution in subsequent operations. Connect pump equipment so that fluid flow will be in the reverse direction of normal flow. Use mineral spirits, Federal Specification TT-T-291, or kerosene, Federal Specification VV-K-211, or dry cleaning solvent, Federal Specification P-S-661. Flush core in reverse direction for 30 minutes or until solution appears clean. Reverse lines and flush ap- proximately 15 minutes in the opposite direction. Drain cooler. (5) Remove carbon deposits, engine oil, gums, lead deposits, and foreign contamination by flushing cooler in opposite direction to normal oil flow for 30-60 minutes. Use solvent cleaning compounds conforming to Specification MIL-C- 6864. Reverse lines and flush in opposite direction for 15 minutes. (6) Remove plug installed in bypass ((3), above) opening and block cooling section opening. Flush for 15 minutes to clean bypass passage. Remove plug from cooling section opening and replace in bypass opening. (7) Rinse cooler for 10 minutes by cir- culating clear petroleum solvent such as dry- cleaning solvent, Federal Specification P-S-661, or kerosene, Federal Specification VV-K-211. System shall be suitably filtered to prevent circulation of foreign matter. (8) Flush cooler with a preservative oil consisting of three parts MIL-L-6082, Grade 1065, and one part MIL-C-6529, or, for systems employing MIL-L-7808 oil, preservative oil MIL-C-8188B, or equivalent, in preparation for shipment or storage. Connect cooler to pump equipment and flush in each direction for 10 minutes, checking the mesh screen after each flush to insure that no metal particles have appeared. After flushing operations, install plugs in inlet and outlet ports. (9) When the coolers have been cleaned it will be necessary to recoat them with zinc chromate primer per MIL-P-8585. In order to insure that the coating covers the entire core, the oil ports should be plugged and the cooler dipped in the zinc chromate. The dip solution should be prepared as follows: 1 part MIL-P-8585 to 1½ parts JAN-T-171. (10) It is important that the dip tank be covered, continuously stirred, and frequent checks on the viscosity be made as the JAN-T- 171 is so volatile that the concentration may change rapidly. After the cooler is dipped in the primer it should immediately be blown out with compressed air from both sides to insure against plugging. The nozzle used to blow air through the core should be a narrow slit 3 to 4 inches long. It is recommended that line air pressure at about 100 psi be used. (11) The tanks may be sprayed with primer after the dip for appearance, if desired. For spray, the proportions should be: 1 part MIL-P- 8585 to 1 part TT-6-916B. d. Inspection. Refer to paragraph 6-3 and (1) through (4), below. (1) Oil cooler assemblies. Inspect oil cooler assemblies for dented tubing or bent fins. Inspect gasket contact surfaces for burs and raised metal. Seal all oil cooler openings. Pressure check coolers by pumping engine oil (OE) into coolers at 400 psi hydrostatic pressure. Coolers must hold 400 psi for ten minutes without loss of pressure. Release pressure, drain oil, and flush with dry-cleaning solvent or mineral spirits paint thinner. Identify leaking coolers for possible repair. (2) Thermostatic bypass valves. Inspect engine and transmission oil cooler thermostatic bypass valves for stripped or damaged threads. Check operation of valve assemblies by im- mersing valve in warm water. Check tem- perature of water with accurate thermometer. Gradually raise temperature of water to tem- perature indicated on valve cover. Valves marked 148 F must travel ¼-inch between 80 F and 185 F. Remove valve from water and clean with dry-cleaning solvent or mineral spirits paint thinner. Replace valve assembly when travel is less than ¼-inch. (3) Oil cooler hoses. Inspect oil cooler outlet and inlet hoses for breaks and abrasions in woven shielding. Replace hose when woven shielding is broken or abraided. (4) Oil cooler screens. Inspect oil cooler screens for bent, cracked, or broken mounting brackets. Check for torn or broken screening. 6-188