how to diagnose a bad idler/tensioner pulley?

[04ctd]

got a used Tahoe, 2007, almost 100k miles.

it has a random intermittent pulley noise.

sounds just like the Trailblazers did, that they did the recall on the pulley for.

problem is, it has 2 fan belts, so it has 2 tensioners, and 1 idler on the big belt

and it only does it ever so often, AC is not a factor.

what's best way to find the bad one?

pull the belts and feel for wobble?

[domin8]

How do the belts look? Are the tensioners tight against the belts?

[ezdaar]

engine off, remove belt from tensioner. Grab it and try to wiggle it towards radiator.. does it move? try the tensioner arm and pulley. if any slop. its bad...

[taylorjm]

Someone told me once that when it's making noise, take a piece of pvc pipe and put it down by the pulley in question, and the other end to your ear (try to not touch the pipe to anything that's moving). You should be able to isolate the problem.

[04ctd]

How do the belts look? Are the tensioners tight against the belts?

yes, look good. previous owner looked to be a "jiffy lube" type of person who did the cheap maintenance.

Someone told me once that when it's making noise, take a piece of pvc pipe and put it down by the pulley in question, and the other end to your ear (try to not touch the pipe to anything that's moving). You should be able to isolate the problem.

that sounds, i had heard the trick on putting a long screwdriver on a valve cover to find a noise, the pipe trick sounds neat.
it never does though...unless i am late, in dress clothes, and the wife is already screaming LETS GO


tks Ez, gonna pop the belts off & wiggle test them all.