Component Tests and General Diagnostics

Fig. 2 Power Steering Pressure Gauge Connections. Lumina w/2.5L Engine:

When performing system test procedures, power steering pressures can easily exceed 1000 psi. Extreme caution must be exercised when performing these tests to prevent personal injury.

This procedure has been modified by Chevrolet service bulletin No. 90-45-3B.
1. Raise and support vehicle.
2. Remove high pressure pipe from pump. Catch any fluid that may drain out.
3. Install hoses J-38049-25 and J-5176-30 or equivalents to pump.
4. Lower vehicle and install pressure gauge J-5176-D or equivalent as shown in Fig. 2.
5. Open valve on pressure gauge.
6. Start engine and allow system to reach operating temperature. Stop engine and check fluid level, add if necessary.
7. Start engine and check pressure.
8. Pressure reading should be 80-125 psi. If pressure is above 200 psi, check hoses for restrictions and poppet valve for proper assembly.
9. With engine running, close valve fully three times for not more than five seconds each time. Each reading should show at least 1250 psi.
10. If pressures recorded are high enough and within 50 psi of each other, the pump is operating normally.
11. If pressures recorded are high enough but not within 50 psi of each other, the control valve in the pump is sticking. Remove but do not disassemble control valve and clean it with crocus cloth or a fine hone to remove any burrs.
12. If pressures recorded are less than 1250 psi, replace flow control valve and recheck. If pressures are still low, inspect rotor and vanes.
13. Shutoff engine and remove pressure gauge.
14. Raise and support vehicle and install high pressure pipe to pump.
15. Lower vehicle and check fluid level.