Checking and assembly operations on the power steering system


Damage to the power steering can be traced to lack of oil in the hydraulic system. Due to the high system pressure in the hydraulic cicuit, even minor leaks may cause fluid loss and damage to the power pump.

Grunting noises when turning the steering wheel or foaming in the reservoir are indicative of lack of oil and/or air drawn in. Before topping up the reservoir, however, repair any leaks remaining on the intake side and replace the defective part on the pressure side.

Checking the steering system for leaks

With the engine idling, turn the steering wheel to the stop position and keep it in this position. This causes the maximum possible line

Check all line connections for leaks in this position and retighten if required.

Test for approx. 10 sec. If the test is run for a longer time, allow a short break approx. every

Porsche 993 Engine Compartment

Important note

The rack-and-pinion steering gear and the power pump must not be repaired or dismantled.

The steering gear is available as a spare part. See spare parts catalogue.

Power steering pump toothed belt The pretension of the toothed belt cannot be

Checking fluid level in the power steering

The reservoir is fitted on the right in the engine compartment.

Check the fluid level* with the engine idling and without operating the steering system. Correct fluid level:

In the case of reservoirs with a transparent upper section (first version used), the fluid level must be between the min. and max. marks on the reservoir. If the reservoir does not have a transparent upper section, the level must be between the two marks on the dipstick attached to the lid. Unscrew the lid and wipe the dipstick clean. Screw the lid back on, remove it again and check the fluid level.

Bleeding the steering system

1. To fill the whole system after fitting new steering assemblies, lines or heavy hydraulic fluid loss, start the engine briefly several times and switch off engine immediately after it has started. During this operation, the fluid level in the reservoir falls rapidly. The fluid level in the reservoir quickly decreases during this process, and hydraulic fluid* therfo-re must be filled in continously. Never allow the reservoir to be drawn empty.

3. Turn steering wheel several times rapidly from stop to stop to allow the air to escape from the cylinders. When the pistons have reached the end positions of their travel, do not pull harder on the steering wheel than would be required to turn the steering wheel (this helps to prevent unnecessary pressure build-up).

4. Observe fluid level during this operation. If level continues to fall, top up until the fluid level remains constant in the reservoir and until no air bubbles rise in the reservoir when the steering wheel is turned.


The oil level in the reservoir must not rise by more than 10 mm when the engine is stopped If the fluid levels deviate from each other by more than 10 mm when the engine is stopped or running, respectively, excessive air is trapped in the hydraulic fluid.

2. If the fluid level in the reservoir no longer falls when the engine is started briefly, start the engine and run it at idle speed.

5. With the engine running at idle speed, top up to correct fluid level (between min. and max. marks) without turning the steering wheel.

* Porsche started to fill the brake systems with Pentosin CHF 11 S (green) in March 1996. ATF was used before then. Pentosin and ATF are miscible. This means that Pentosin can be used to top up the fluid level in 993 vehicles before the aforementioned introduction date. On vehicles with Pentosin filling, always fill or top up the brake system with Pentosin.

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