TM-9-2815-200-35 Maintenance Manual for AVDS-1790-2M AVDS-1790-2A and AVDS-1790-2AM Engines Download
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Table 4-9. Para 4-22 Para 4-23 Para 4-24 4-22. Checking Cylinder Compression a. General. For instructional purposes in this section all fuel injector nozzle and holder assemblies will be removed and a compression test will be made on all cylinders. If troubleshooting indicates that only one cylinder requires a compression check, it may be done by rem oving the nozzle from the questionable cylinder. Warning; When only one cylinder is checked, there is the possibility of the engine firing on the other cylinders when compression check is being made. To prevent engine firing, remove all nozzles then check cylinder compression. Unless all nozzles are removed, the engine motoring rpm will be below desired cylinder checking rpm. b. Starting Engine. Check the vehicle batteries to assure full charge and replace if necessary. Refer to the pertinent operator’s manual for engine starting procedures. Start engine and allow engine to reach normal operating temperature and then stop engine. Cut off fuel supply so engine will not deliver fuel while performing compression test. c. Compression Test. Remove the fuel injector nozzle and holder assemblies from each cylinder (para 4-17). Install the compression checking adapter and compression gage (figs. 4- 184 and 4-185) and motor engine with the starter motor. Crank engine several seconds, or until compression gage reaches maximum reading. Cylinder compression pressure should be between 330 and 480 psi. High cylinder pressures are caused by combustion of lubrica- ting oil in the engine combustion chamber. If this occurs, allow combustion gases to escape prior to taking compression reading. Install 1. Position new fuel injectc r nozzle gasket (A) on end of compression adapter - 4!’10-795-7961. Apply a light coating of grease on gasket so it adheres to adapter when installed in cylinder. Note. Be sure gasket is installed with open face toward adapter. 2. Install adapter (B) into fuel injector nozzle holder opening and tighten securely using fixed open end wrench - 5120-871-7198 Remove 1. Remove adapter (B) frc m fuel injector nozzle holder opening using fixed open end wrench -5120-871-7198 as shown in figure 4-16$. 2. Remove and discard gasket (A). Figure 4-184. Installing or removing compres- sion adapter—4910-795-7961 (cylinder compress:ion test). 4-94