Getting set to replace my serpentine belt on my 2007 5.4L because I don't know when it was last replaced and it looks like the edge is beginning to fray. From searching the archives, I see that some advise that I replace the idler pulley at the same time. My question is - which one to replace? It looks like there is one directly above the tensioner pulley and also one on the driver's side just above the power steering pump. I suppose I can replace both but is there one that is more prone to causing problems.

 

There should be 3. 1 grooved and 2 smooth. If they spin freely and have no wobble or noise to them, I'd let em ride and just change the belt. Check the tensioner pulley also.

 

Maybe they meant to replace the whole tensioner because it too can ware out because of the constant tension on the spring. I know there are tensioner marks to go by to see if the belt needs replacing but not sure how to know if the tensioner is worn. Maybe the 3 pulleys good enough though

 

Just check them as noted in the previous post. It only takes a minute to loosen the belt enough to pull it off the pulleys.

Check all of them, if suspect at all, buy a new pulley or bearing along with your belt. Pull the belt back on and go get your new parts.

 

What is causing the belt to fray ??

 

Age, mileage