Steering: Service and Repair
WM 489729 Flushing the steering system
Technical values
Flushing the steering system
Information
The following components of the steering system must also be replaced on all vehicles:
- Reservoir
- Suction hose from reservoir to hydraulic pump (referred to as "suction hose" in the text)
- Return line from steering fluid cooler to reservoir (referred to as "return line" in the text)
After replacing components, the steering system must be flushed with approx. 3 - 4 litres of steering fluid. This will flush impurities, resulting from defective components and/or wear, out of the steering system. A second mechanic is required for some of the repair work.
Work preparation: Hose (shop-made)
Return line extension, for draining steering fluid.
Length of hose (shop-made) for return line extension (adopted from the Cayenne)
- => Inner diameter: +12 mm+3 mm
- => Length: +1,700 mm+300 mm
1. Remove underbody protection and place a suitable container for collecting steering fluid underneath, e.g. 10-litre canister -> 519219 Removing and installing cover for front underbody 519219 Removing and installing Cover For Front Underbody.
2. Disconnect return line -1- at the steering fluid cooler and drain steering fluid.
3. Disconnect return line at the reservoir -4- and remove it completely (Figure shows engine compartment on the Cayenne as an example).
Reservoir (1), suction hose (3) and return line (4)
4. Fit the hose (shop-made) onto the connection piece for the steering fluid cooler (return).
Information
Use a sufficiently large container to collect steering fluid, e.g. a 10-litre canister.
- Secure the free end of the hose (shop-made) in the collection container (strong flow of fluid).
Guide the other end of the hose (shop-made) into the steering fluid collection container.
5. Replace and fit suction hose -3- and reservoir -1- (Figure shows engine compartment on the Cayenne as an example).
Reservoir (1), suction hose (3) and return line (4)
6. Close off connection piece for the return line -4- at the reservoir.
7. Fill the reservoir up to the MAX marking until the fluid level no longer drops.
Engine is not started!
8. Raise the vehicle until the wheels are no longer touching the floor. Turn the steering fully to the left and right and hold it at full lock for approx. 30 seconds on each side until the level no longer drops. Continually check the fluid level and fill to the MAX marking again.
CAUTION
Escaping (spraying) Pentosin
- Risk of skin and eye irritation
- Swollen water hoses
-> Wear protective gear (goggles, gloves).
-> If water hoses come into contact with Pentosin, clean them thoroughly with water IMMEDIATELY.
-> Swollen water hoses must be replaced.
9. Procedure for flushing the steering system
Vehicle must be standing on its wheels.
9.1. - Have a can containing approx. 3 - 4 litres of steering fluid ready. First mechanic continually checks the fluid level in the reservoir and checks that Pentosin flows safely into the container.
The reservoir must not run dry!
NOTICE
Rotating components
- Danger of limbs being trapped or severed
-> Do not reach into rotating parts.
-> Do not start the engine until the second mechanic has clearly confirmed that it is safe to do so.
9.2. - Second mechanic sits in the vehicle and
starts the engine for max. 1 second following consultation with the first mechanic.
9.3. - Second mechanic must also start turning the steering to the left and right at full lock on either side.
9.4. - Stop the engine IMMEDIATELY after flushing the system for 1 second! Fill the can with steering fluid if necessary and check the flow in the collection container (secure it to prevent it from slipping out!).
9.5. - Check the fluid level in the reservoir and continually top it up each time the engine is started. Then
restart the engine several times following consultation with the first mechanic until the steering fluid (3 - 4 litres) you are using to flush out the system has been flushed through.
Then stop the engine IMMEDIATELY.
10. Once the flushing process is complete, remove the hose (shop-made).
11. Fit new return line.
12. Bleed the steering system and correct the fluid level in the reservoir. -> 4890IN Test and assembly work on power steering 4890IN Test and assembly work on power steering
13. By shining a torch in the reservoir, check for shimmering metal particles (like metallic paint) in the steering fluid. Don't confuse these with air bubbles! If metal particles are visible, flush the system again.
14. Fit underbody protection -> 519219 Removing and installing cover for front underbody 519219 Removing and installing Cover For Front Underbody.