Diagnostic Manual, Chassis and Drivetrain,
Hydraulic Test Program - Hydraulic Oil Pump Test
Preparation for Test
|1. Depressurize rear axle hydraulic system by slowly opening bleeder screw (57a).
2. Connect test gauge (038) with hose (038e) to rear axle distribution fitting (57) in place of bleed screw (57a).
3. Check oil level in oil reservoir, correct if necessary.
To perform this rest, the oil fill quantity must be increased by 0.5 liters. If the oil reservoir was empty, the hydraulic oil pump must first be bled by disconnecting the high pressure flexible hose at the steel line. Run the engine and hold the hose into a container until the oil exits free of bubbles.
4. Connect HHT (refer to section 0).
5. Disconnect return line (T) at oil reservoir (2) and using a suitable hose (061), hold it in a measuring glass.
Monitor oil level during testing, air must not be allowed to enter the system through the hydraulic pump.
||Hydraulic oil pump
| 250 bar at rear axle distribution fitting.
||Engine: at Idle.
HHT activation: raise
Observe test gauge needle until pressure no longer increases.
> 180 - 190 bar delivery capacity at idle
> 0.2 l/min.
|Delivery pressure < 180 bar,
Delivery capacity < 0.2 l/min:
Replace hydraulic oil pump
Delivery pressure < 180 bar,
Delivery capacity > 0.2 l/min:
Replace leveling valve.