My 1999 F-150 started giving out an unearthly scream and a burning rubber smell a couple of days ago so I parked it and found that the passenger-side idler grooved metal pulley had lots of rocking motion on its shaft. I removed the pulley and saw that its bearing was well and truly destroyed.

I ordered a new pulley and got one from CarQuest, their number 38019. It is the right size, grooved, but non-metallic and has a sealed bearing.

There is a note on the side of the CarQuest box that I didn't notice before I had the pulley installed. Here's what it says: "The bearing in this product is greased and sealed and therefore does not require the dust cover that may have been used on the original pulley. Check for interference before reusing the original dust cover."

The original pulley had a very thin flat washer on the securing bolt and a slightly conical plastic piece between the washer and the bolt torx or splined head. Is this combination the dust cover? I put it all back on with the replacement pulley and don't see anything that could be called interference, although it is true there would be more wrench/ratchet clearance without the conical piece. I'd appreciate any comments on what CarQuest might mean by "interference".

I found the tensioner that I had to loosen was moved by means of putting a 15 mm socket and a breaker bar on the head of the bolt that holds its pulley. There was some bolt-loosening necessary before the tensioner actually could be seen to pivot away from the belt. When I went to re-tension the belt after the pulley replacement, I wasn't sure how much to tighten the bolt, or even whether doing any further tightening than allowed the tensioner pulley to contact the belt was necessary. Maybe the spring action of the tensioner should be allowed to do the tensioning. Any advice?