Idler pulley replacement?

Bad idler pulley--Bearing actually fell apart when I was investigating a noise under the hood. Removed the bolt holding the pulley to the block bracket and got a Dayco replacement. Unfortunately, when all was hooked back up to the serpentine belt, the bolt works its way loose when the pulley spins.

I got a used pulley and bearing assembly at a scrap yard and will install tonight. Should I use Loctite blue on the threads. The threads on the original bolt and this scrapped pulley and bolt are fine as is the female threads on the bracket that accepts the pulley bolt.

Any idea how tight I should crank down on the idler pulley bolt? When I removed bolt and pulley at the scrap yard, it was snug, but not overly tight as I just needed a 8" long wrench and because of its location, you can't get a lot of leverage anyway. I just don't want to bind up the bearing by overtightening, but also don't want the pulley bolt to come loose again, hence the Loctite blue.

Been searching the web for other similar issues with the idler pulley bolt backing out and think I have found the problem. Another individual had a similar issue on a Chevy when he used the original idler pulley bolt with a replacement plastic/resin pulley.

Seems the cup washer/dust shield on the original bolt just hits the inner rim of the pulley where the bearing is seated. When the belt turns the pulley, the washer/dust shield also turns and the bolt loosens. Additional engine vibrations keeps letting the bolt loosen to the point where the pulley comes loose and the belt slips off.

I'll be installing the original style metal idler pulley from the scrap yard and returning the Dayco to Advance Auto Parts for a refund.

Hopefully the recycled part has some years left in it, as it still turns smoothly.

1998 Chevy Cavalier Front Wheel Drive Automatic

How do you replace Idler pulley?