TM 10-3930-671-24 taking  control  of  the  throttle,  slight  variation  (hunting)  in engine speed may occur. This should not be considered an   abnormal   condition.   When   the   engine   speed   has stabilized, check maximum no-load governed speed. Engine No-Load Governed Speed Chart Truck, Engine Model No-Load Speed Setting TMD27 Engine 2600 rpm, nominal Range: 2550 2650 rpm Truck, Engine Model Engine Hydraulic By-Pass Speed TMD27 Engine 2000 2200 rpm, approximately Full Throttle Engine Stall RPM • Stall   tests   must   be   performed   with   the parking brake applied and wheels blocked up above the ground to prevent movement. Be careful that the truck does not   move   unexpectedly   when   operating the engine and converter at stall. Unexpected  movement  of  the  truck  could cause injury or death to personnel. • Do  not  run  engine  and  converter  at  stall longer   than   necessary   to   take   the   rpm readings or longer than 30 seconds at one time. Then, shift transmission into NEUTRAL   for   15   seconds   and   run   the engine  at  one  half  speed  for  1-2  minutes to   cool   torque   converter   oil.   Excessive temperature    250°F    (120°C)    max    will overheat the converter and cause damage to converter, seals, and fluid. NOTE • Hydraulic bypass test must be done first to be sure that the engine is running properly. • Be sure that transaxle fluid level has been checked and is correct, and all mechanical checks  of  shift  linkage  and  brake-inching pedal adjustment have been made before running a stall test. Refer to Section 7.2, Transmission Troubleshooting. • Add load on forks  to  increase  weight  and prevent inadvertent drive wheel spin. • Use  of  the  service  brakes  (with  inching) will release the transmission clutches and prevent stalling of the torque converter. • A stall test is perhaps the most  important and   useful   test   for   quickly   determining engine condition. The  parking  brake  should  hold  the  truck  from  moving under full stall torque. If not, it requires adjustment, or the service brakes need adjustment or servicing. NOTE Prior to performing stall test, it is recommended that you first: • Park truck safely. • Return all controls to neutral. • Put blocks under upright rails and raise the drive wheels off the ground. • Put blocks under frame. • to Part 8, Brakes. Refer to Part 8, Brakes F-89