Hydraulic System Pressure Test
- Disconnect pressure hose from pump. Connect Adapter (MB991217 on turbo or SOHC models, and MB991548 on non-turbo or DOHC models) to pump outlet. Connect Adapter (MB990994 on turbo or SOHC models, and MB991549 on non-turbo or DOHC models) to steering gear hose. Connect pressure hoses and Pressure Gauge (MB990662). See Fig 1 .
- 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 shutoff valve of pressure gauge and check relief pressure. See 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 the 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 | 114 (8) | |
| Relief Pressure | 1209-1309 (85-92) | |
| No-Load Pressure | 114-142 (8-10) | |
| Rack & Pinion Retention Pressure | 1209-1309 (85-92) | |