TM10-3930-660-20 18-5. PISTON PUMP -  TEST/REPLACE This task covers: a. Removal b. Installation c. Testing Initial  Setup Tools Materials/Parts Tool Kit, Automotive Mechanics Container,  6Gal. Hydraulic Oil (App. C, Item 36) Lifting Device, Capacity 5 ton. Lockwasher  (19) o-ring (21) Cup and Plug Set Tags (App. C, Item 51) Test Equipment In-line Flowmeter Reference TM10-3930-660-10 Test Tee Hydraulic Hose Equipment  Condition Vehicle parked on level ground. Boom raised and blocked. Transmission cover removed, para.  16-6. W A R N I N G Hydraulic oil in the system can be under pressures over 3000 psi with the engine OFF . ALWAYS relieve pressure in hydraulic lines before attempting to remove any component in the hydraulic system. With engine OFF, starter switch in RUN position, and MLRS attachment on the ground, move control levers through all operating positions several times to relieve line pressure. Relieve pressure in hydraulic oil tank by loosening filler cap very slowly. Failure to follow these precautions could result in serious personal injury. 18-11