Compressor/Pump: Testing and Inspection

Checking Hydraulic Pump













1.1 Disconnect return line (T) from fluid reservoir (2)
- Connect one end of the drain hose to the return line (T) and place the other end in the graduated container

NOTE: To measure the hydraulic pump's supply rate.

CAUTION: Ensure that hoses are routed securely.

NOTE: When the bypass valve in the suspension-control module opens the fluid pressure in the return line rises to approximately 2 bar.

1.2 Use clamp to close return line (T).
- Connect drain hose (061) to the return line (T) and place the other end in a graduated container (The engine compartment cover has been removed at this juncture)

NOTE: To measure the hydraulic pump's supply rate.

CAUTION: Ensure that hoses are routed securely.

NOTE: When the bypass valve in the suspension-control module opens the fluid pressure in the return line rises to approximately 2 bar.

DANGER:
- Risk of accident from vehicle starting off by itself when engine running. Risk of injury from contusions and burns if you insert your hands into the engine when it is started or when it is running
- Secure vehicle to prevent it from moving off by itself.
- Wear closed and close-fitting work clothes.
- Do not touch hot or rotating parts.

2 Start engine and allow to idle
3 Checking delivery rate of pressure oil pump Route hose attached to return line (T) into a suitable graduated container

CAUTION: Ensure that the reservoir contains sufficient fluid. Never let the pump suck air. If supply rate is below Replace hydraulic/tandem pump

4 Switch off engine
5.1Connect return line (T) to fluid reservoir (2)
5.2 Connect hose to return line (T)

DANGER:
- Risk of injury to skin or eyes from hydraulic fluid spraying out under pressure Risk of poisoning from swallowing hydraulic fluid
- Render the hydraulic system pressureless before commencing work on system Wear protective clothing and eye protection.

6 Drain hydraulic system

CAUTION: General notes for working on vehicles with level control / ADS

7 Connect tester to suspension-control module (3)
8 Fill the reservoir with fluid (2)

CAUTION: Raise the fluid level to approximately 0.5 litres above the MAX graduation (a) on the dipstick (2a) for the test

DANGER:
- Risk of accident from vehicle starting off by itself when engine running Risk of injury from contusions and burns if you insert your hands into the engine when it is started or when it is running
- Secure vehicle to prevent it from moving off by itself
- Wear closed and close-fitting work clothes
- Do not touch hot or rotating parts

9 Start engine and allow to idle
10 Press suspension-control module lever (3a) to "fill" (F) position
11 Check hydraulic pump supply rate

CAUTION: Because the pressures are considerable, keep the test as brief as possible

NOTE:
- The suspension-control module's bypass valve limits the supply pressure of the hydraulic pump The bypass valve emits a whistling noise as it opens.
- Bypass valve release pressure if the bypass valve's opening pressure is substantially lower than specification, and supply rate at idle
- Replace hydraulic/tandem pump if the bypass valve's opening pressure is substantially higher than specification
- check rear suspension-control module

12 Set level controller lever to center position

DANGER:
- Risk of injury to skin or eyes from hydraulic fluid spraying out under pressure Risk of poisoning from swallowing hydraulic fluid
- Render the hydraulic system pressureless before commencing work on system Wear protective clothing and eye protection

13 Disconnect tester at level controller
14 Recharge hydraulic system