Power Steering Pressure

Testing of steering fluid pressure in steering system is performed to determine whether or not oil pump and power steering unit are functioning normally.

Power steering system test is used to identify and isolate hydraulic circuit difficulties. Prior to performing this test, following inspections and corrections, if necessary, must be made.

• Inspect pump reservoir for proper fluid level.
• Inspect pump belt for proper tension.
• Inspect pump driver pulley condition.

1. Place a container under pump to catch fluid when disconnecting or connecting hoses.
2. With engine NOT running, disconnect pressure hose at power steering pump and install Power Steering Tester (J-29877-A). See Fig 1 . Gauge must be between shutoff valve and pump. Open shut-off valve.
   Fig 1: Installing & Using Power Steering Tester (J-9877-A)

   Courtesy of ISUZU MOTOR CO.
3. Check fluid level. Fill reservoir with power steering fluid, to "Full" mark. Start engine, then turn steering wheel and momentarily hold it against a stop (right or left). Turn engine off and check connections at tester for leakage.
4. Bleed power steering system. See BLEEDING POWER STEERING SYSTEM  under LUBRICATION.
5. Start engine and check fluid level. Add power steering fluid if required. When engine is at normal operating temperature, increase engine speed to 1500 RPM.
   CAUTION: Do not leave shutoff valve full closed for more than 5 seconds, as the pump could become damaged internally.
6. Fully close shut-off valve, and record highest pressures.
   • If pressure recorded is within 1350-1420 psi (9300-9800 kPa), pump is functioning within specifications.
   • If pressure recorded is higher than 1420 psi (9800 kPa), valve in pump is defective.
   • If pressure recorded is lower than 1350 psi (9300 kPa), valve or rotating group in pump is defective.
7. If pump pressures are within specifications, leave valve open and turn (or have someone else) turn steering wheel fully in both directions. Record highest pressure and compare with maximum pump pressure recorded in step 6). If this pressure cannot be built in either side of power steering unit, power steering unit is leaking internally and must be replaced.
8. Shut engine off and remove testing gauge.
9. Reconnect pressure hose, check fluid level and make needed repairs.
10. If problem still exists, steering and front suspension must be thoroughly examined.