when i turn my impreza steering as far to left or right there is screeches and the steering wheel becomes jerky 3/4 way round, also the pulley on the ps pump slows down when wheels are as far round as can go. the belt seems tight so what will it be? or will i change belt and see

 

Does sound like belt,checked fluid?

 

mechanic had a quick look at it today and said belt was tight enough (but its 2003 plate car so not sure last time was changed) hes replacing belt on Thursday will get him to look at fluid then. If its not belt is it likely to be ps pump?

 

If its not leaking fluid and all topped up to the correct level,if the new belt doesn't cure it then it's likely to be the pump. ICP do them new for £395 also give AS Performance a ring as Alyn is very competitive on prices.
or 2nd hand see Matty from the breakers section.

 

OK thanks at that price would need to be 2nd hand

 

Sounds like the belt skipping.
If you have black dust on the alternator then the belts passed it..