Flushing The Hydraulic
Power Steering System
The power steering system should be flushed whenever replacing a steering component. Failing to carry out this important step could shorten the life of the replacement component by circulating contaminants from the pipe work and dirty fluid into the new part.
Flushing can be carried out using specialist equipment however if this is not available flushing the system can be achieved using the following procedure.
- Ensure that the fluid reservoir is clean. If there is a filter in the reservoir check that it has been back flushed and that fluid runs through it without restriction. If in doubt replace the reservoir. Reconnect the low pressure pipe to the reservoir checking that the clamps at the reservoir and pump are providing an air tight seal. In operation this pipe work is under suction pressure.
- Flush the pump and pipe work from the reservoir to the steering rack. Disconnect the high pressure pipe from the pump at the connection on the steering rack. Pour clean power steering fluid into the reservoir and allow it to drain through the pipe work and flow into a suitable container under gravity. This should be continued until the fluid is seen to run clear. Reconnect the high pressure line to the steering rack.
- Flush the steering rack and the return pipe work to the reservoir. Disconnect the return line at the reservoir and direct into a suitable container. Plug the return connection on the reservoir then fill the reservoir with steering fluid to the “MAX” mark. Raise the front wheels off the ground. Throughout the next stages maintain fluid level in the reservoir, this really needs two people. Slowly turn the steering wheel from side to side once to expel old fluid from the rack. Disable the ignition and crank the engine on the starter motor several times allowing the pump to force fluid into the waste container. The amount of fluid required will depend on the size of the system and the amount of contamination but should be around 1 litre. After flushing procedure the fluid entering the waste container should be clear. Reconnect the return line to the reservoir and carry out the bleeding procedure. Turning over the pump with the starter motor only may seem time consuming but it will reduce the possibility of introducing air into the system and will stop power steering fluid being sprayed around the engine bay.
Remember to use the power steering fluid specified by the vehicle manufacturer or refer to our information on types of power steering fluid.
We would recommend flushing the system and renewing the power steering fluid every 50.000 miles even if no components have been replaced to prolong the life of the steering components.