Hydraulic System Pressure Test
- Disconnect pressure hose from pump and connect Adapters (MB991217-A to pump outlet; MB990994 to steering gear hose), Pressure Hoses (C-4535) and Pressure Gauge (C-3309-E). Start engine, bleed air from system and turn steering wheel several times with vehicle not moving until power steering fluid temperature reaches about 122-140°F (50-60°C).
- Temporarily adjust idle speed to 900-1100 RPM. Fully close shut-off valve of pressure gauge and check pressure. Refer to the HYDRAULIC PRESSURE SPECIFICATIONS table. If pressure is not within specification, steering pump should be repaired or replaced.
- With shutoff valve open, check for no-load pressure. See HYDRAULIC PRESSURE SPECIFICATIONS table. If pressure is not within specification, check oil lines and rack and pinion.
- Fully close shutoff valve of pressure gauge. Turn steering wheel to left or right and check retention pressure. Refer to the HYDRAULIC PRESSURE SPECIFICATIONS table. If pressure is not within specification, rack and pinion should be repaired or replaced.
HYDRAULIC PRESSURE SPECIFICATIONS
| Application | psi (kg/cm2 ) | |
|---|---|---|
| Oil Pressure Switch | ||
| Activation Pressure | 213-284 (15-20) | |
| Deactivation Pressure | 100-171 (7-12) | |
| Relief Pressure | 1067-1166 (75-82) | |
| No-Load Pressure | 114-142 (8-10) | |
| No-Load Pressure Max. | 213 (15) | |
| Rack & Pinion Retention Pressure | 1067-1166 (75-82) | |