'97 Legacy GT wagon, loud shrieking squeal on startup that goes away after 15 seconds or so. Pop quiz:

A) Power steering fluid low?

B) Power steering acessory belt shot?

C) Belt tensioner loose?

D) Other?

 

I say belt needs to be replaced.

 

Loose/slipping belt.
Examine all the belts (with the engine off of course). Press on them with your thumb midway between the pullies, if tension is correct the belt should deflect a small amount, no more than 1/8-1/4". Also look at the underside of the belt (the side that contacts the pullies) and check for cracks or glazing. If it's shiny that indicates it has been slipping.
If the belts look ok but are loose tighten them to spec and the noise should stop. Be sure not to overtighten them as this can damage the bearings in the driven accessories. If the belts show signs of wear or slippage or are original, they should be replaced. Get new ones from the dealer as they aren't that expensive and are better than the ones you get at the parts store.

 

Thanks guys. The squeal is only on startup, never when turning, so I think the belt has just now begun to go. I also checked the fluid and it is a little bit low, just above the "L" mark, so I will drain and replace the steering fluid as well. Man, that stuff STINKS. It must be made from the rear end of the dinosaur :-)

 

Low fluid won't make the PS belt squeal. You could have a problem with the pump but that doesn't happen often, usually the only reason they go bad is from doing donuts in the snow or dirt with the wheel at full lock.
Draining/replacing the PS fluid is not a normal maintenance item, it won't hurt to do so but probably will have minimal benefit.

 

The manual has stern warnings not to mix types of fluid, and I have no idea what is actually in the resevoir, so I thought I'd drain it just to be sure it is all 100% the same brand/type.

 

starter
shaft maybe

 

An update on this: I checked all the belts, and they are fine and at the correct tension (no more than a few MM of deflection), so I am kinda stumped. The sound only happens on a cold startup; once the engine is warm the sound does not happen again. It is not a starter noise, I know exactly what that sounds like as I've replaced the starter in the car once before. All the belts look nearly new, not a shiny spot or bare thread anywhere. Any other ideas?

 

I wonder if the belts are just glazed over and are slipping for a bit at startup. It may not show any wear on the belt, but if its glazed it will slip.

Edit. Looks like Mulder already said that.