Test and Assembly Work on Power-Assisted Steering
General
Damage to power-assisted steering results from lack of oil in the hydraulic system. Because of the high oil pressure in the hydraulic circuit, even small leaks can cause loss of fluid and damage the servo pump.
Grinding noises when the steering is on lock or the formation of foam in the reservoir indicates lack of oil and/or the sucking in of air. Before filling the reservoir, any existing leaks must be eliminated on the suction side. Alternatively, the defective part on the pressure side should be replaced.
Only Pentosin CHF 11 S may be filled into the reservoir. Pentosin CHF 11 S can be ordered with the following part number:
Quantity supplied 1 liter = 000.043.203.33.
Important note
Rack-and-pinion steering gear and servo pump must not be repaired or dismantled.
Servo-pump drive belt
The drive-belt pretension cannot be adjusted.
Checking the steering system for leaks (visual check)
With engine idling, turn steering wheel as far as the stop and hold still. The maximum possible line pressure results in this way.
In this position, check all pipe connections for leaks and retighten if necessary.
Perform the check for a maximum of ten seconds. A longer check should always be interrupted by a brief pause after approximately ten seconds.
Checking Pentosin CHF 11 S hydraulic fluid in the power-steering system
The reservoir is located in the engine compartment. There are two marks on the dipstick located on the reservoir cap. One side bears the mark "Cold" for a cold engine (approximately 20°C) and the other "Hot" for a hot engine (approximately 80°C).
Check the fluid level (Pentosin CHF 11 S) with the engine stationary and cold (approximately 20°C).
1. Open engine compartment lid. Open reservoir cap.
2. Wipe dipstick. Close reservoir cap and open it again. The fluid level should lie in the hatched area beneath the "Cold" mark (mark = maximum level at 20°C. Top up with Pentosin if necessary.
The upper "Hot" mark is intended for a fluid temperature of 80°C.
In no case add too much Pentosin!* The respective marks are for the maximum fluid level at the "COLD" or "HOT" temperature.
Note: If assembly work was performed previously, check the fluid level with the engine idling and without operating the steering.*
Multiple steering operations (maneuvering) with the engine switched off change the fluid level in the reservoir - the fluid level rises. In this case, the engine must be run for at least 5 seconds before the fluid level is checked.*
Bleeding the steering system
1. To fill the whole system after the installation of new steering components or lines or after a substantial loss of hydraulic fluid, briefly start the engine a few times and, when it fires, switch it off again immediately. This procedure causes the fluid level in the reservoir to fall rapidly, so constantly add Pentosin CHF 11 S. * The reservoir must not be sucked dry.
2. 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 to run at idling speed.
3. Rapidly turn the steering wheel from stop to stop several times so that the air can escape from the cylinders. At the end positions of the piston, do not pull the steering wheel with more force than is necessary in order to turn the steering (to prevent unnecessary build-up of pressure).
4. Observe fluid level during this procedure. If it continues to fall, add fluid until the level in the reservoir remains constant and no more air bubbles rise in the reservoir when the steering wheel is turned.
5. Correct the fluid level with the engine at idling speed - without operating the steering.*
When topping up or filling in Pentosin, make sure that Pentosin does not come into contact with the coolant hoses! In order to avoid overfilling and thus overflowing, observe the specifications. If coolant hoses come into contact with Pentosin, thoroughly clean them with water IMMEDIATELY. Replace visibly swollen coolant hoses!