TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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1. Install gage assembly -4910-870-6283 (A) on adapter - 4910-795-7961 and tighten securely. 2. Crank engine using starter motor and check cylinder compression. It must be within 330 to 480 psi at engine cranking speed. 3. Depress gage vent valve (B) to release pressure and reset gage to zero after compression reading is taken. Recheck reading. Test compression on all cylinders in the same manner. d. Compression Variation. After all 12 cylinders are checked, determine the pressure difference between high and low cylinder readings. This variation should not exceed 70 psi. e. Engine Motoring RPM. If compression data exceeds the above specifications. the engine motoring rpm should be checked to be sure that it is 140 to 180 rpm. Compression should be checked again to confirm the previous readings before submitting an engine for overhaul. 4-23. Adjusting Intake and Exhaust Valve Clearance When checking and / or adjusting clearance, it is necessary to first remov valve e the cooling fan vanes, fans, fan shroud, top covers, and oil coolers to gain access to valve adjusting screw cover plates. Refer to Table 4-9 for in- structions pertinent to the removal of the above items, and the procedures involved in the ad- justment of the intake and exhaust valve clearances. Figure 4-185. Checking cylinder compres- sion using gage assembly-4910-870-6283 and compression adapter-4910-795-7961. 4-95