4890IN Test and assembly work on power steering
WM 4890IN Test and assembly work on power steering
Information
General information
- The rack-and-pinion steering gear and power-steering pump must not be repaired or dismantled!
- Always replace the O-rings on hydraulic lines!
- Ensure absolute cleanliness at all times!
- The reservoir must always be replaced if individual or multiple components, such as the tandem pump, PDCC valve blocks (FA/RA), PDCC anti-roll bars (FA/RA) are replaced.
- If system faults still occur after replacing a component (another component is defective), the reservoir does not have to be replaced again.
- Steel flexi-pipes must not be kinked or crushed.
- Observe safety requirements! -> 4303AW Safety requirements for Porsche Dynamic Chassis Control (PDCC) Service Precautions
Damage to the power steering is caused by insufficient oil in the hydraulic system. Even small leaks can cause the fluid to escape and damage the servo pump as a result of the high oil pressure in the hydraulic circuit.
Grunt-like noises on turning the steering to full lock or foam formation in the reservoir indicate a shortage of oil and/or the absorption of air. Before filling the reservoir, any existing leaks must be eliminated. In this case the oil level in the reservoir must be checked with the engine running as well as stopped! If the oil level drops to the bottom of the reservoir or bubbles rise up, then there is air in the hydraulic system.
Only Pentosin CHF 202 may be used in the reservoir. Pentosin CHF 202 can be ordered under the following part number: 1-litre container = 000.043.203.33.
A dipstick with a MAX/MIN marking => see figure is mounted on the reservoir cap. The markings are for a fluid level with a cold engine (approx. 20 °C)!
Checking fluid level
Information
- The reservoir is located at the front left of the engine compartment.
- A dipstick with MAX-MIN marks is mounted on the cap of the reservoir. They are for a fluid level with a cold engine (approx. 20°C).
- The MAX mark can easily be exceeded at higher temperatures.
Overview (shown with PDCC)
CAUTION
Increased risk of accidents and material damage if too much Pentosin CHF 202 is filled in or if Pentosin CHF 202 comes into contact with the coolant hoses when filling or topping up.
- It is possible to overfill the system, causing Pentosin CHF 202 to overflow onto coolant hoses and other components.
-> Before checking the fluid level, run the engine for approx. 20 seconds. Multiple steering operations (manoeuvring) will change the fluid level in the reservoir. Check the fluid level.
-> If coolant hoses come into contact with Pentosin, clean them thoroughly with water IMMEDIATELY.
-> Replace visibly swollen coolant hoses.
Check the fluid level (Pentosin CHF 202) when the engine is not running and when it is cold (approx. 20°C).
The fluid level must be between the MAX and MIN marks => see figure.
1. Start engine and run it at idle speed for approx. 20 seconds. Switch off engine.
2. Open engine cover and the lid of the engine compartment cover.
3. Open reservoir cap.
4. Wipe dipstick. Close and then reopen cap. The fluid level must be in the indicated range (MAX/MIN level at approx. 20 °C). Top up with Pentosin if necessary.
Bleeding the steering system
Information
The steering system and PDCC have a shared reservoir. If repairs are carried out on one system, it is necessary to bleed both systems.
- The reservoir must always be replaced if individual or multiple components, such as the tandem pump, PDCC valve blocks (FA/RA), PDCC anti-roll bars (FA/RA) are replaced.
- If system faults still occur after replacing a component (another component is defective), the reservoir does not have to be replaced again.
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1. After installation is complete, raise the vehicle so that the wheels are no longer touching the ground.
2. Open engine cover and reservoir.
3. Fill reservoir up to the MAX marking, until the level no longer drops.
4. Then turn the steering to the left and to the right. Hold the steering on 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 if necessary.
5. Lower the vehicle onto its wheels. Briefly start the engine, let it run for approx. 1 second and add Pentosin again. This procedure causes the fluid level in the reservoir to fall rapidly, so constantly add more Pentosin CHF 202. The reservoir must not be sucked dry.
6. If the fluid level in the reservoir does not fall any further when the engine is briefly turned over, start the engine and let it run at idling speed.
7. Turn steering on full lock several times to left and right at idling speed and observe the fluid level during this procedure (second worker required). If it continues to fall, add fluid until the level in the reservoir remains constant and no more air bubbles circulate in the reservoir when the steering wheel is turned.
8. Switch engine off and set the correct fluid level. This must be between the MIN and MAX markings.
When the correct level has been reached, no air bubbles must be circulating in the reservoir and the fluid level must no longer drop.