ARMY TM 9-2815-259-24 AIR FORCE TO 38G1-125-2 MARINE CORPS 09249A/09246A-24 4-41 (b)     Check for excessive “blueing” or “coking” of oil along the complete length of shaft.   Excessive “blueing” or “coking” along the complete length of shaft indicates either a possible lack of lubrication caused by engine failure or improper operation, such as hot shutdowns. (8)     Perform turbocharger bench inspection. (a) Mount turbocharger in vise. (b)     Check shaft rotation and clearance by rotating shaft with both hands.  Shaft should turn freely, however, there may be a slight amount of drag. NOTE There will be some “play” because the bearings inside center housing are free floating. (c) Pull up on compressor end of shaft and press down on turbine end while rotating shaft.   The compressor wheel and turbine should not contact the housing at any point. (d)     Check shaft end play by moving shaft back and forth while rotating.  There will be some end play, but the wheels should not contact the housings. c. Replacement. (1)     Remove turbocharger, refer to step a. (2)     Perform inspection procedures, refer to step b.  If turbocharger fails any inspection portion, the unit is defective and must be replaced.  If turbocharger passes inspection, continue with step c (3) listed below. (3)     Test turbocharger per step d.  Replace turbocharger if unit fails any portion of the tests.  If turbocharger passes tests, install per step e. d. Test. (1)     Inspect turbocharger, refer to step b. (2)     Prelube turbocharger center housing bearings, refer to step e (3). (3)     Perform radial bearing clearance test as follows: (a) Fasten a plunger-type dial indicator to turbocharger mounting base.  Assemble an extension adapter and 2.0 in. (51 mm) indicator extension rod onto dial indicator. (b)     Grasp rotating shaft at both ends and move shaft toward indicator then away from indicator.  Use care to move shaft in same direction as dial indicator tip travels and apply equal pressure at both ends of shaft.  Refer to Figure 4-38.