TM 5-3805-260-24 Pump makes noise and the steering cylinder rod does not move smoothly. 1.  Air in the steering hydraulic circuit. 2.  The pump has too much wear. 3.  Loose connection of the oil line on the inlet side of the pump. 4. The viscosity of the oil is wrong. 5.  The relief valve opens at low oil pressure. 6.  The oil level in the tank is low. a.  Bleed hydraulic oil lines. b.  Check pump,  repair or replace as necessary. c.  Tighten line connection. d.  Replace oil with oil of proper viscosity. e.  Adjust relief valve as necessary. f.  Fill tank to proper level. STEERING HYDROAULIC SYSTEM PUMP EFFICIENCY CHECK For  any  pump  test  at  a  given  rpm,    the  pump  flow (gpm)  at  100  psi  (7.0  kg/cm²)  (690  kPa)  will  be  larger than   the   pump   flow   (gpm)   at   1000   psi   (70.0   kg/cm²) (6900 kPa). The    difference    between    the    pump    flow    of    two operating pressures is the flow loss. Method of finding flow loss... Pump flow at 100 psi 57.5 gpm (litre/min)* Pump flow at 1000 psi   -52.0 gpm (litre/min)* Flow loss 5.5 gpm (litre/min)* Flow  loss  when  given  as  a  percent  of  pump  flow  is used as a measure of pump performance. Example of finding percent of flow loss... Percent (             gpm flow loss            ) x100 = of flow (Pump flow @ 100 psi)          ) loss or     (*5.5  )    x 100 =  9.5% (*57.5) If  the  percent  of  flow  loss  is  more  than  10%,    pump performance is not good enough. *Numbers  in  examples  are  for  illustration  and  are  not values  for  any  specific  pump  or  pump  condition.    See SPECIFICATIONS for pump flow of a new pump at 100 psi and 1000 psi. Test On The Machine Install a 9S2000 Flow’ Meter.  Measure pump flow at 100 psi (7.0 kg/cm²) (690 kPa) and at 1000 psi (70.0 kg/cm²) (6900 kPa) with engine at 2000 rpm. NOTE:  See  Tee  Test  Tooling  Chart  Form  No.  REG009 10. Formula I: Percent (gpm100 psi - gpm @ 1000 psi) x 100 = of flow (gpm @ 100) loss Test On The Bench If  the  test  bench  can  not  be  run  at  1000  psi  at  a  high rpm,    do  the  first  part  of  the  test  with  the  pump  shaft rotation at 1000 rpm.  Measure pump flow at 100 psi (7.0 kg/cm²) (690 kPa) and at 1000 psi (70.0 k, g/cm²) (6900 kPa).  Then to measure the pump flow, s for the last part of the test,  see SPECIFICATIONS for: Pump rpm at 100 psi with the engine at 2000 rpm. Formula II: Percent (gpm @ 100 psi - gpm @ 1000 psi) x 100 = of flow (gpm @ 100 psi @ 2000 rpm  ) loss STEERING CONTROL VALVE The  values  shown  in  the  SPECIFICATIONS  are  for hydraulic  oil  that  is  I  50°F  (65°C).    Run  the  engine  and operate the hydraulic system to increase the temperature of the hydraulic oil.  Stop the engine and loosen the filler cap to let the airout of the supply tank before a test hose and gauge are installed or removed. Relief Valve for the Steering Circuit The steering control valve is located under the operator's station. 2-113