When I first start out driving, turn the wheel as I back out of the driveway I get a 'pop' noise coming from the front suspension, loud enough to hear over the warming engine. I hear it occasionally under other circumstances, particularly moving slowly on an incline while turning the wheel.

I've checked the swaybar mounts, all good. Lower ball joints don't seem to have a problem, tierods, centerlink all seem fine. My lower bushings could use replacement but I've seen much worse. Car tracks fine, holds alignment, no noticeable slop - no symptoms other than the 'pop' that point to front end trouble. Brake system was updated to new recently so it isn't a caliper piston popping/sticking.

I had my wife turn the wheel back and forth while I watched the suspension. I could not get it to reproduce the pop while I was down there but I did notice some vertical movement up and down on the idler arm shaft.

I jacked the car up and I am able to rock the whole steering rack up and down - I see about 1/2" of vertical movement up and down where the idler arm attaches. The nut that hold it all together is tight.

Is this way out of spec indicating the need for a bushing replacement? My other old volvo is still in surgery so I have no model to compare it to.