Dirkprop

Hi. Thanks for the response. I will replace the o-ring and flush the system as suggested and will keep you posted.

I am a noobie with a 2007 Subaru Outback 3.0l, 131000 kms, which has developed a strange problem with the power steering. When the car is cold there is a little noise in the pump when turning the wheel hard left or right and when the car is hot this noise disappears. Stranger still, and this is the real problem, I gradually lose power steering assist when the car warms up and especially when driving at slow speeds with many turns e.g. city driving. It gets so bad that I have to manhandle the wheel into the driving straight position after each turn. Yet if the car is parked up for a few hours and has had a chance to cool down, the steering returns to normal until the car heats up again. I have replaced the belt and checked fluid levels, but the problem persists. Any ideas for fix would be welcome.