Diagnostic Manual, Chassis and Drivetrain,
Hydraulic Test Program - Hydraulic Oil Pump Test
Preparation for Test
|1. Check oil level in oil reservoir,
correct if necessary.
2. Model 129
Unscrew connecting rods (54, 55) at front and rear leveling valve levers
(set levers to neutral position).
Unscrew connecting rod at leveling valve lever (3a).
3. Depressurize rear axle hydraulic system by slowly opening bleeder screw
(3p). Connect drain hose and place into container.
4. Connect test gauge (038a) to rear axle leveling valve bleeder screw (S2).
5. Model 129
Set both leveling valve levers to position "F" (fill).
6. Model 129
Open pressure supply screw (50a) by maximum of 1 turn.
7. Disconnect return line (T) at oil reservoir (2) and using a suitable
hose, hold it in a measuring glass.
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
|Possible cause/Remedy 1)
Connect test gague to rear axle leveling valve connection S2
|Engine: at Idle
Set leveling valve lever(s) to position "F" (fill).
Observe test gauge needle until pressure no longer increases.
|> 133 bar
Delivery capacity at idle
> 0.2 l/min.
|Delivery pressure < 133 bar,
Delivery capacity < 0.2 l/min:
Replace hydraulic oil pressure pump
(SMS, Job No. 32-640)
Delivery pressure < 133 bar,
Delivery capacity > 0.2 l/min:
|1) Observe Preparation
for Test, see 22.