So, I realized there is a bunch of noise from the engine. I took the belt off to see which thing is making it, and found that it was three things - idler, tensioner, and alternator. All had bearings in various stages of failure. Alternator pulley was visibly wobbling. Idler was super trashed, grinding like a stripper with arthritis. Tensioner was best of them, but still bad, with clicking and catching.

Idler is on the left, tensioner on the right.


I love the groove worn into it. It's probably original from 1997.

The thing I don't get is why these things are listed as two different part numbers. The tensioner I got as a replacement was metal. The new idler was the same plastic design. They look exactly the same to me.



Same outer size, same inner bore. The bearings in them are a little different, with the tensioner one having a slightly thicker inner race, but the inner and outer dimensions are the same, so it can be just a manufacturer difference.

The only difference is that the tensioner one is held with a left-hand bolt and the idler with a right-hand bolt. Which can't possibly matter to the pulley itself.

 

How do you know if you need to replace the idler pulley, or the tensioner pulley, or if you need to replace both ? There's a "kit" parts option online, that replaces several things.





Tutuapp 9Apps

 

If you have a mechanic's stethoscope you can use it to listen.

Or you can do it the simple way. Take off the belt. Then spin each pulley by hand (except the big one on the engine crankshaft - you ain't turning that over without some leverage).

If it spins smooth and quiet, it's good. If it makes noise, feels loose, wobbly, or crunchy - you probably need a new one.

 

That wear on the idler pully is crazy. Probably seen a few belts in its life.

 

Yeah, I have never seen another one that bad.